Category Archives: Health & Medicine

Amazon indigenous people barely get dementia. Could a pre-industrial lifestyle protect against Alzheimer’s?

2 Replies

Nearly 1 in 10 Americans over the age of 65 have dementia, and as the U.S. struggles with an aging population, the proportion of elderly people with Alzheimer’s and other neurodegenerative diseases is bound to increase. But in the Amazon basin, where some indigenous people still employ a subsistence lifestyle as they have for hundreds of years isolated from industrialized society, the rate of dementia hovers at around just 1%. These findings, reported by a new study from the University of South California, suggest that the Western lifestyle may be seriously putting people at risk of dementia in old age.

“Something about the pre-industrial subsistence lifestyle appears to protect older Tsimane and Moseten from dementia,” said Margaret Gatz, the lead study author and professor of psychology, gerontology and preventive medicine at the University of South California.

The Tsimane have little or no access to health care but are extremely active and consume a high-fiber diet that includes vegetables, fish and lean meat. (Photo/Courtesy of the Tsimane Health and Life History Project Team)

Gatz and colleagues traveled to the Bolivian Amazon jungle, where they closely studied the elderly of the Tsimane’ and Mosetén tribes — two indigenous peoples that have remained largely isolated from urban life elsewhere in the country.

The Tsimane’ number about 16,000 people living in mostly riverbank villages scattered across about 3,000 square miles of the Amazon jungle. They are forager-farmers who fish, hunt, and cut down trees with machetes, which keeps everyone very physically active throughout their lifetimes.

The neighboring Mosetén, which number around 3,000 and have close cultural ties with the Tsimane’, also reside in rural villages and rely on subsistence agricultural work. However, they live closer to towns, have schools, and access to health posts, as well as access to roads and electricity. Within the last decade, the Mosetén have also received cell phone service and running water.

Researchers employed computer tomography (CT) brain scans, cognitive and neurological tests, and questionnaires to assess the mental health among the Tsimane’ and Mosetén aged 60 and over.

According to the results, the study found just 5 cases of dementia among 435 Tsimane’ and one case among 169 Mosetén, which is much less than the rate of incidence in Western countries. Previously, studies of indigenous populations in Australia, North America, Guam, and Brazil found dementia prevalence ranging from 0.5% to 20%. The authors note that the apparent higher rate of dementia among older adults from indigenous tribes elsewhere in the world could be due to their higher contact with their industrialized neighbors, and subsequent adoption of more sedentary lifestyles.

In the same over-60 groups, the researchers also diagnosed about 8% of elderly Tsimane’ and 10% of Mosetén with mild cognitive impairment (MCI) — the stage between the expected cognitive decline of normal aging and the more serious decline of dementia. This condition is characterized by memory loss and a decline in cognitive abilities, such as language and spatial reasoning. The MCI rates were comparable to those encountered in high-income countries.

In high-income countries with high rates of dementia among older adults, the population generally does not engage in the recommended amount of physical activity and has a diet rich in sugars and fats. As a result, older adults are more susceptible to heart disease and brain aging. In contrast, the Tsimane’ people have unusually healthy hearts for their age. That’s not surprising considering they also have the lowest prevalence of coronary atherosclerosis of any population in the world.

Alzheimer’s has been previously associated with hypertension, diabetes, cardiovascular diseases, physical inactivity, and even air pollution. It’s no coincidence that these chronic diseases and health problems are staples of modern Western lifestyles.

In 2021, the same team from the University of South California found that the Tsimane indigenous people of the Bolivian Amazon experience less brain atrophy than their American and European peers. Their decrease in brain volume happened at a rate that was 70% lower than in Western populations.

“We’re in a race for solutions to the growing prevalence of Alzheimer’s disease and related dementias,” said Hillard Kaplan, a study co-author and professor of health economics and anthropology at Chapman University who has studied the Tsimane for two decades. “Looking at these diverse populations augments and accelerates our understanding of these diseases and generates new insights.”

If the Tsimane’ and Mosetén offer any indication, a pre-industrial lifestyle can offer significant protection against dementia. But that doesn’t mean we can all revert to foraging in the woods and living under the stars. In case someone is romanticizing life in the Amazon jungle, bear in mind that the Tsimane’ have an average of nine children per family who live an average of just over 50 years compared to the world average of 71.5 years. So while it may be true that indigenous Amazon people rarely suffer from dementia at old age, what’s certain is that even fewer actually make it that far.

The findings were published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

New test maps acidity in the mouth to spot cavities before they form

2 Replies

The phrase ‘prevention is better than the cure’ is a fundamental principle of modern health, and your oral health should be no different. One of the best ways to prevent cavities is by brushing and flossing correctly. But by now, most people do this and they still end up with some caries eventually. Taking prevention to the next level, scientists at the University of Washington have now developed an optical-based method that can identify the most at-risk teeth by mapping high acidity in the dental plaque that covers the teeth.

Shining light on teeth covered with a florescent dye solution can reveal where the enamel is most at risk from acidity. Credit: University of Washington/IEE Xplore.

Dental plaque is produced by bacteria that live in our mouths as a byproduct as they consume sugars, starches, and other bits of foods that haven’t been properly cleaned from the teeth. If plaque stays on the teeth for more than a few days, it hardens and becomes a substance called tartar. In time, the microorganisms that form on the plaque release acids that wear down the tooth enamel, then the next layer called dentin, before reaching the pulp. When acid attacks the pulp, you’ve officially gotten a new cavity.

But what if we could monitor this acidic activity and stop it before it crosses a point of no return that triggers the cavity formation? That’s exactly what researchers at the University of Washington set out to do. They’ve devised a system, which they call O-pH, that measures the pH levels, or acidity, of the plaque covering each tooth under inspection.

In order to map the acidity of the plaque, a person’s teeth are first covered in a non-toxic, safe chemical dye that reacts with light to produce fluorescent reactions. An optical probe then detects these fluorescent reactions, whose signals can reveal the exact acidity of the underlying dental plaque.

The proof of concept was demonstrated on a small sample of 30 patients, aged 10 to 18. Children and teenagers were selected because their enamel is much thinner than that of adults, which makes detecting any sign of erosion — and consequently a potential cavity — early on very important. The tooth acidity was read before and after sugar rinses, as well as pre- and post-professional dental cleaning.

In the future, this acidity test could be standard practice in dental practices. Eric Seibel, senior author and research professor of mechanical engineering at the University of Washington, says that when a patient comes in for routine teeth cleaning, “a dentist would rinse them with the tasteless fluorescent dye solution and then get their teeth optically scanned to look for high acid production areas where the enamel is getting demineralized.” The dentist and patient can then form a treatment plan to reduce the acidity and avoid costly cavities.

“We do need more results to show how effective it is for diagnosis, but it can definitely help us understand some of your oral health quantitatively,” said Manuja Sharma, lead author and a doctoral student in the UW Department of Electrical and Computer Engineering.  “It can also help educate patients about the effects of sugar on the chemistry of plaque. We can show them, live, what happens, and that is an experience they’ll remember and say, OK, fine, I need to cut down on sugar!”

The O-pH system was described in the journal IEEE Xplore.

A coat against our troubles: new compound can transform air filters into pathogen-killing machines

2 Replies

A joint research venture between the University of Birmingham and private firms NitroPep Ltd and Pullman AC has produced air filters that are highly effective at killing bacteria, fungi, and viruses, including the SARS-CoV 2 virus, the infamous coronavirus.

Image via Pixabay.

The secret of these filters’ effectiveness is a chemical called chlorhexidine digluconate (CHDG). This is a potent biocide that can kill pathogens within seconds of coming into contact with them. Air filters coated in this substance can prove to be a powerful tool against airborne pathogens around the world, according to the researchers that designed them.

Removing the gunk

“The COVID-19 pandemic has brought to the forefront of public consciousness the real need for new ways to control the spread of airborne respiratory pathogens. In crowded spaces, from offices to large indoor venues, shopping malls, and on public transport, there is an incredibly high potential for transmission of COVID-19 and other viruses such as flu,” says Dr. Felicity de Cogan, Royal Academy of Engineering Industry Fellow at the University of Birmingham, and corresponding author of the paper.

“Most ventilation systems recycle air through the system, and the filters currently being used in these systems are not normally designed to prevent the spread of pathogens, only to block air particles. This means filters can actually act as a potential reservoir for harmful pathogens. We are excited that we have been able to develop a filter treatment which can kill bacteria, fungi and viruses—including SARS-CoV-2—in seconds. This addresses a global un-met need and could help clean the air in enclosed spaces, helping to prevent the spread of respiratory disease.”

The filters were tested in both laboratory and real-life conditions to determine how effective they were at removing air-borne pathogens, and the results are stellar.

In the lab, the filters were covered with viral particles of the Wuhan strain of SARS-CoV-2, alongside control filters. They were then checked periodically over a period of more than one hour to see how these pathogens fared. While much of the initial quantity of viral particles remained on the surface of the control filters for the experiment’s length, all SARS-CoV-2 cells were destroyed within 60 seconds on the treated filters.

Experiments involving bacteria and fungi that commonly cause illness in humans — such as E. coli, S. aureus, and C. albicans— yielded similar results. This showcases the wide applicability of the filters.

To determine how well these fitlers would perform in real-life situations, treated filters were installed in the heating, ventilation, and air conditioning systems on train carriages in the UK alongside control filters in matched pairs on the same train line. These were left to operate for three months before being removed and sent to the lab for analysis — which involved the researchers counting any bacteria colonies that survived on the filters.

No pathogens were found on the treated filters, the team explains. Furthermore, this step showed that the treatment was durable enough to withstand three months of real-world use while maintaining their structure, filtration functions, and anti-pathogen abilities.

“The technology we have developed can be applied to existing filters and can be used in existing heating, ventilation and air conditioning systems with no need for the cost or hassle of any modifications,” Dr. de Cogan explains. “This level of compatibility with existing systems removes many of the barriers encountered when new technologies are brought onto the market.”

NitroPep Ltd is now building on these findings in order to deliver a final marketable version of the coating.

The paper “Efficacy of antimicrobial and anti-viral coated air filters to prevent the spread of airborne pathogens” has been published in the journal Nature Scientific Reports.

Rat infestation in Washington DC has produced two cases of rare virus infection

Leave a reply

Washington, DC, has a rat problem. According to the Centers for Disease Control and Prevention (CDC), this has led to the emergence of the first two official cases of hantavirus in humans in the city.

Image credits Wolfgang Vogt.

Wildlife has its own share of viruses and pathogens to deal with, as do people. Sometimes, however, when these two groups live in close proximity, pathogens can evolve to cross from one to the other. When this takes place from wildlife or livestock to humans, this is known as zoonosis. The coronavirus pandemic started as a zoonosis.

One genus of viruses that can comfortably infect both rodents and humans is known as orthohantavirus, or simply hantaviruses. These are widespread through rodent populations such as city rats, where they cause asymptomatic infections. However, people can become infected with these viruses as well, most commonly through exposure to rat urine or feces, although saliva or bites can also transmit the virus.

Washington DC’s rat problem has led to the emergence of two known cases of hantavirus infection, the CDC reported Thursday. Transmission from one infected person to another is almost unheard-of with hantaviruses, so concerns about brewing epidemics are far from the CDC’s mind. The infections were recorded in 2018 and have been successfully treated.

Still, the situation poses a risk for the health of people in Washington DC, who should take steps to protect themselves from the rodents.

Vermin threat

“Although extremely rare, the two SEOV cases presented in this report highlight the importance of physicians including hantavirus infection in their differential diagnoses in patients with compatible symptoms and history of animal exposure or travel and underscore the importance of reporting notifiable infectious disease cases to health departments for investigation and response,” the CDC’s report explains. “These cases also serve as a reminder to the public to minimize risk for infection by following recommended hygiene practices.”

Hantavirus infection in people can lead to a host of respiratory and hemorrhagic diseases which can easily become fatal. Fortunately for the cases recorded in DC, the strain identified in the two infected individuals is a milder “Old World” strain called the Seoul virus. Old World hantaviruses cause a disease called hemorrhagic fever with renal syndrome (HFRS). In contrast, “New World” hantaviruses, which are present in the Americas, cause a much more severe respiratory infection known as hantavirus pulmonary syndrome (HPS)– which is much deadlier.

HFRS starts out as a generic infection with fever, chills, nausea, and headache, but can then progress to low blood pressure, acute shock, vascular leakage, and acute kidney failure, the CDC notes. The severity of HFRS varies by the strain of hantavirus that causes it, and can reach up to 15% fatality. In the case of the Seoul virus, fatality rates are around 1%. Both individuals reported-on by the CDC made a full recovery.

HPS also begins as a generic infection with fever, chills, and aches, but quickly progresses to an acute, life-threatening phase after about a week. The patient’s lungs and heart are affected; the lungs fill with fluid, and patients require hospitalization and ventilation within 24 hours. HPS is fatal in about 38% of cases, according to the CDC. The deadliest such virus, the Sin Nombre virus, spread by the deer mouse, has a fatality rate of about 50%.

HPS and the Sin Nombre virus first came in the crosshairs of US health officials following an outbreak of deadly respiratory disease in the Four Corners region. In total, 48 cases were identified in that year, 27 of which were fatal. The CDC finally tracked the virus down to rodents in the area, and it gained the moniker of Sin Nombre virus (the virus with no name) during this process.

The Seoul virus has a much lower prevalence in the US, and spreads from the common brown rat, which travelled to all corners of the world on European ships (hence, the virus is known as an “Old World” virus). The virus is present worldwide but was first described in Korea, near Seoul. It is considered a rare pathogen among humans.

This is what makes the two cases reported-on by the CDC notable. Patient A was a healthy male, a 30-year-old maintenance worker who had “frequent rodent sightings at his workplace”. He contracted the disease in May 2018 and made full recovery after receiving treatment. Patient B was an unrelated case. This 37-year-old man with chronic kidney disease who worked as a dishwasher and plumber’s assistant contracted the disease in November 2018; it is unclear from what source. The CDC notes that he did not own any pets, had not recently travelled outside of the US, and was unaware of exposure to rodents at any point in his daily life. He also made a full recovery after receiving treatment.

The CDC believes these two cases were caused by the city-wide rat problem in Washington DC, which they explain has been worsening for years now.

“Rodent overpopulation in DC is well documented by increased complaints via the Citywide Call Center to the Rodent Control Program, and the DC Department of Health has amplified efforts to address this public health threat,” the CDC explains.

The cases serve as a reminder of the dangers of rat infestation in our cities, and should motivate the public to follow recommended hygiene practices to insulate themselves from the risk. Meanwhile doctors should keep in mind that the virus is active in the area and look out for signs of hantavirus infection in their patients.

COVID-19 seems to affect the brain — even in mild cases

Leave a reply

From early on in the pandemic, there’s been strong evidence of COVID-19 can take a toll on the brain and the nervous system – with symptoms like the loss of smell and taste as hallmarks of early infection. Now, a new study further demonstrated the mental toll of the virus, which was linked with significant, lasting brain abnormalities even in mild cases.

Image credit: Pixabay.

Researchers found that COVID-19 seems to reduce the brain’s gray matter, mainly in areas linked with memory processing and smell. These changes were observed in both people who required hospitalization and in those who had a less severe infections. The damage seen in the brain was beyond the structural changes that normally happen with age and could not be explained by other factors.

The study looked at changes in the brains of 785 people aged 51-81, who previously contributed brain scans to the UK Biobank, a large-scale database of brain imaging data from over 45,000 UK residents. Out of the participants, 401 had a COVID-19 infection sometime between March 2020 and April 2021 – with 4% hospitalized for infections.  

The remaining 384 participants didn’t have COVID-19 but matched the infected participants in age, sex, and COVID-19 risk factors, such as whether they had diabetes. They served as the control group as they had no record of confirmed or suspected COVID-19. Everyone in the study was subject to two brain scans to allow comparisons.

“Using the UK Biobank resource, we were in a unique position to look at changes that took place in the brain following mild—as opposed to more moderate or severe—SARS-CoV-2 infection,” Genaëlle Douaud, lead author on the study, said in a statement. “We saw a greater loss of gray matter volume in infected participants.”

COVID-19 and the brain

The team used magnetic resonance imaging (MRI) to look at the brains. MRI uses a magnetic field and radio waves to generate images of tissues in the body. The MRI scans showed clear shrinkage in the brains of the people who caught the disease. Participants of the study caught COVID-19 about 4.5 months before their second scan.

The infected group had larger tissue loss in specific regions of the cerebral cortex – the outer surface of the brain. Shrinkage was most pronounced in the orbitofrontal cortex (which plays an important role in sensation) and in the parahippocampal gyrus (which is important for encoding new memories).

At the same time, those infected with COVID-19 had a larger reduction in overall brain size than the control group without the virus, the study showed. The authors also found tissue damage in areas of the brain linked with the primary olfactory cortex – a structure that gets sensory information from scent-detecting neurons in the nose.

On average, those who had the virus showed 0.2% to 2% greater tissue loss and damage over the course of about three years, compared with the control group. Estimates suggest that adults lose between 0.2% to 0.3% of gray matter in regions related to memory each year, so the extra loss would be out of the ordinary.

“It’s the only study in the world to be able to demonstrate before vs after changes in the brain associated with SARS-CoV-2 infection,” Naomi Allen, chief scientists at the Biobank, said in a statement. “Collecting a second set of scans has generated a unique resource to enable scientists to understand how the virus affects internal organs.”

The study stops short of explaining how impactful these changes are on the brain, and how long-lasting they are. However, problems associated with COVID-19 appear to be more pervasive than initially thought, and the specter of long COVID will likely continue for a long time to come.

The study was published in the journal Nature.

Scientists discover how genes from our parents may shape our behavior

Leave a reply
Credit: Pixabay.

One major point of contention among psychologists has always been the nature versus nurture debate — the extent to which particular aspects of our behavior are a product of either inherited (i.e. genetic) or acquired (i.e. learned) influences. In a new study on mice, researchers at the University of Utah Health focused on the former, showing that genes inherited from each parent have their own impact on hormones and important neurotransmitters that regulate our mood and behavior.

Intriguingly, some of these genetic influences are sex-specific. For instance, the scientists found that genetics inherited from mom can shape the decisions and actions of sons, while genes from dad have biased control over daughters.

I got it from my Mom and Dad

Like chromosomes, genes also come in pairs. Both mom and dad each have two copies, or alleles, of each of their genes, but each parent only passes along one copy of each to the child. These genes determine many traits, such as hair and skin color.

But it’s not only our outward appearance that is influenced by genes. In a new study, researchers found that tyrosine hydroxylase and dopa decarboxylase — two genes that are heavily involved in the synthesis of hormones and neurotransmitters like dopamine, serotonin, norepinephrine, or epinephrine — are expressed differently from maternally versus paternally inherited gene copies. These chemicals play a crucial role in regulating an array of important functions from mood to movement.

The genes are also involved in the production of the adrenaline hormone by the adrenal gland, which triggers the “fight or flight” response when we encounter danger or stress. Together, these pathways form the brain-adrenal axis.

“The brain-adrenal axis controls decision making, stress responses, and the release of adrenaline, sometimes called the fight or flight response. Our study shows how mom’s and dad’s genes control this axis in their offspring and affect adrenaline release. Mom’s control the brain and dad’s control the adrenal gland,” Christopher Gregg, principal investigator and associate professor in the Department of Neurobiology at the University of Utah Health, told ZME Science.

In order to investigate how inherited gene copies introduce maternal or paternal biases in the brain-adrenal axis, the researchers genetically modified mice to attach a fluorescent tag to the dopa decarboxylase enzyme. Using a microscope, they could tell if a gene was inherited from the mother (colored red) or from the father (colored blue).

An investigation of the entire mouse brain revealed 11 regions that contained groups of neurons that only use mom’s copy of the dopa decarboxylase gene. Conversely, in the adrenal gland, there were groups of cells that were exclusively expressed by the gene copy inherited from the dad.

These findings immediately led to an existential question: could our behavior be influenced by these genetic biases? To answer, the researchers analyzed mice with mutations that switched off one parent’s copy in a select group of cells while the rodents were foraging for food.

The mice were left to explore freely so any external influence was kept to a minimum. Their behavior had to be as natural as possible as they encountered various obstacles, which prompted them to either take risks or retreat to safety, before resuming their quest for finding food.

These movements and behaviors look random and chaotic, but a machine algorithm developed by the researchers was able to pick up subtle, but significant patterns. When these foraging patterns were broken down into modules, the researchers were able to identify behavioral differences associated with each parent’s copy of the dopa decarboxylase genes.

“We have faced a lot of skepticism from the scientific community. The way we study decision-making by using machine learning to detect patterns was hard for scientists to understand. The community was surprised to find that such well-studied genes (Th and Ddc) express the Mum and Dad’s gene copies in different brain and adrenal cells. We had to do a lot of work to show how strong the evidence is for our discovery,” Gregg said.

Christopher Gregg pictured. Credit: Jen Pilgreen.

Gregg had been interested in how biological factors influence our decisions since he first came across Daniel Kahneman’s work in behavioral economics while he was still a postdoc. In the 1970s, Kahneman and Amos Tversky introduced the term ‘cognitive bias’ to describe our systematic but flawed patterns of responses to judgment and decision problems.

For instance, the gambler’s fallacy makes us tend to be certain that if a coin has landed heads up five times in a row, then it’s much more likely to land tails up the sixth time. The odds are, in fact, still 50-50. One of the most pervasive and damaging biases is the confirmation bias, which leads us to look for evidence confirming what we already think or suspect. If you’re disgruntled by the current political divides across the world, where each side seems unable to allow that the other side might be right about some things, you can point the finger at confirmation bias in many cases. There are many other biases, though, with Wikipedia listing at least 185 entries.

Now, Gregg seems convinced that these cognitive biases and some decision processes are deeply rooted in our biology, as well as that of other mammals. And with more research, it may be possible to modify maladaptive behaviors in a clinical setting, with potential new treatments for conditions like anxiety or depression.

The main caveat, however, is that all of this work has been performed on mice. Gregg and colleagues now want to develop and apply a new artificial intelligence platform called Storyline Health to human decision-making and behavior. They expect to discover genetic factors that control our behavior and cognition in a similar way to rodents.

“I am very excited about this new area that emerges from our work and merges decision making, machine learning and genetics. We are going to discover a lot of important new things about the factors that shape our decisions,” he said.

The findings appeared in the journal Cell Reports.

A new Omicron subvariant, 30% more contagious, is starting to sweep the world

Leave a reply

I know — we’re all tired of the pandemic and we’re all hoping it’d be over by now. But unfortunately, the virus doesn’t really care about media fatigue or how tired we all are of this pandemic.

While substantial progress has been made on the vaccination front, new variants continue to emerge, and researchers warn that the pandemic is still not done yet. Now, a new Omicron variant (BA.2) is surging in several parts of the world, including the US, UK, and Hong Kong.

Graph made by William Ku, with data from the CDC.

Researchers warned us from the beginning that until we reach herd immunity at a global level, new variants will continue to emerge and we’d still be stuck in a pandemic — and this is exactly what we’re seeing now. After the more contagious Delta variant came in and swooped over the Alpha and Beta variants, Omicron made it all look like a joke.

The contagiousness math adds up very quickly.

Alpha was 50% more contagious than the original Wuhan strain. Delta is 40-60% more contagious than Alpha. Omicron is 105% more contagious than Delta. Now, the BA.2 Omicron variant appears to be 30% more contagious than the original Omicron, and we’re seeing the number of cases spike accordingly.

The emergence of the new subvariant coincides with a wave of lifting restrictions. Countries (especially those with a relatively high level of vaccination) were quick to relax restrictions and ease the political, social, and economic pressure they were causing — but this has come at a cost.

In the UK, the BA.2 variant has become dominant, and while at some point it seemed that the Omicron wave would simply burn out in the country, we’re seeing a new surge in cases and hospitalizations are starting to follow.

What we know about BA.2 Omicron so far

While it clearly appears to be more transmissible (and will likely become dominant across the world), we still don’t know how severe this subvariant is. Lab experiments from Japan suggest that it may have Delta-like characteristics and may cause more severe illness.

“More importantly, the viral RNA load in the lung periphery and histopathological disorders of BA.2 were more severe than those of BA.1 and even B.1.1. Together with a higher effective reproduction number and pronounced immune resistance of BA.2, it is evident that the spread of BA.2 can be a serious issue for global health in the near future,” a study not yet peer-reviewed concludes.

However, a separate study from South Africa found that a similar proportion of individuals with BA.1 and BA.2 infections required hospitalization, and data from Denmark suggests similar hospitalization rates for BA.1 and BA.2.

As is always the case with new variants and subvariants, it’s hard to tell exactly how things stand in the beginning. It’s also curious that while it seems to be taking over in several parts of Asia and Europe, BA.2 transmission in the US seems relatively low.

Importantly, while Omicron BA.2 shows some ability to evade vaccine immunity, it seems that boosters still provide excellent immunity. Overall, BA.2 shows the already well-known Omicron ability to evade some of the protection offered by two shots — but three shots offer over 90% protection against hospitalization.

Image credits: William Ku, with data from the CDC.

Long-term, it seems that booster-provided protection wanes in time, and the rate of booster shot delivery has also slowed down, presumably as people’s interest in the pandemic also wanes. But variants don’t care how much attention you’re paying.

Did we rip the bandaid too soon?

Another reason why BA.2 is spreading so quickly is that many countries have relaxed restrictions — or removed them altogether. Some researchers believe this was done too quickly.

In addition to extra transmissibility, the BA.2 subvariant also appears to be capable of escaping some of the treatments we have for COVID-19. While the original Omicron was capable of evading two of the four monoclonal antibody drugs used in infections in high-risk individuals, a study from New York University suggests that BA.2 can bypass a third drug, sotrovimab.

Researchers also caution that even mild cases can cause lasting brain damage (and potentially other problems as well). A study from Oxford found that the virus produces changes in the brain and may shrink grey matter.

Ultimately, the vast majority of people with booster shots should be able to evade the worst of the virus effects — but they can still be in for an unpleasant ride.

Lead exposure from gasoline has affected the IQ of 1 in 2 Americans since the 1940s

Leave a reply

In the 1920s, researchers realized that you can add lead to gasoline to help keep car engines healthy for longer. But while leaded gasoline was good for cars, it was bad for humans.

Leaded gasoline is highly toxic and in addition to causing a number of health problems, it can also cross the blood-brain barrier and accumulate in some parts of the brain, where it can cause a number of problems, including reducing intelligence. According to a new study, exposure to car exhaust from leaded gasoline affected the IQs of over 170 million Americans alive today, costing the country a collective 824 million IQ points.

Image credits: Joe Mabel.

The findings come from a new study published by Aaron Reuben, a PhD candidate in clinical psychology at Duke University, and Michael McFarland and Mathew Hauer, both professors of sociology at Florida State University. The researchers started from publicly available data on US childhood blood-lead levels and leaded-gasoline use. They then determined the likely lifelong burden of lead exposure of every American alive in 2015. From this, they calculated how much of an intelligence burden this exposure to lead proved to be. While IQ isn’t a perfect proxy to intelligence, it’s still a good population-level indicator.

Previous studies have suggested an association between lead exposure in childhood and a drop in IQ. But when the results came in, even the researchers were surprised.

“I frankly was shocked,” McFarland said. “And when I look at the numbers, I’m still shocked even though I’m prepared for it.”

The results show that over half of all Americans (170 million out of an entire population of 330 million) had clinically significant levels of lead in their blood, resulting in lower IQ levels as adults, as well as a number of potential health problems (such as reduced brain size, greater likelihood of mental illness, and increased cardiovascular disease). The people affected by lead exposure would have each lost, on average, 3 IQ points.

“Lead is able to reach the bloodstream once it’s inhaled as dust, or ingested, or consumed in water,” Reuben said. “In the bloodstream, it’s able to pass into the brain through the blood-brain barrier, which is quite good at keeping a lot of toxicants and pathogens out of the brain, but not all of them.”

Three IQ points may not seem like much, but keep in mind that this is an average for a whopping 170 million people. At its worst, people born in the mid-late 1960s may have lost 6 IQ points on average. At a population level, this is a considerable margin — and even though leaded gasoline was banned in the US in 1996, the effects of the problem are still visible today.

“Millions of us are walking around with a history of lead exposure,” Reuben said. “It’s not like you got into a car accident and had a rotator cuff tear that heals and then you’re fine. It appears to be an insult carried in the body in different ways that we’re still trying to understand but that can have implications for life.”

Thankfully, the era of leaded gasoline is finally over. Most countries banned it two decades ago, but only last year, in 2021, the era of leaded gasoline was finally over as the last stocks were used in Algeria (which had continued to produce leaded gasoline until July 2021).

Leaded gasoline is a good example of an exciting technology that turns out to be very bad for the environment and for human health. But while leaded gasoline has been phased out, there are plenty of other sources of pollution still affecting our brains, lungs, and hearts.

Journal Reference:  “Half of US Population Exposed to Adverse Lead Levels in Early Childhood,” Michael J. McFarland, Matt E. Hauer, Aaron Reuben. Proceedings of the National Academy of Sciences, March 7, 2022. DOI: 10.1073/pnas.2118631119

Pandemic restrictions could be linked to 750,000 fewer dengue cases

Leave a reply

Almost three-quarters of a million fewer cases of dengue were registered in 2020, which researchers suspect is linked to COVID-19restrictions on people’s movements and interactions, according to a new study. For the researchers, targeting places such as schools could greatly reduce dengue transmission hot spots and play a key role in stopping the spread of the disease.

Image credit: Flickr / Vaccines at Sanofi

Dengue is a big cause of acute morbidity in over 120 countries worldwide, with sustained increases year on year. Countries in Southeast Asia and the Americas regions are the worst affected, with over two million cases reported there in 2020 — but as the planet continues to heat up, more and more areas become vulnerable to dengue.

The virus isn’t transmitted human to human but by the Aedes aegypti species of mosquitoes which needs hot temperatures. Hot and humid tropical climates are ideal for transmission, and cases generally peak between June and September. Symptoms typically include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash. Overall, dengue infects some 400 million people a year, killing 40,000.

For dengue, the COVID-19 pandemic was a unique opportunity to better understand how different environments and human mobility contribute to transmission. That’s why an international group of researchers decided to carry out the first multi-continent study of the effects of public health and social measures on dengue incidence.

“Before this study, we didn’t know whether COVID-19 disruption could increase or decrease the global burden of dengue,” Oliver Brady, study co-author, said in a statement. “While we could assume reduction in the human movement would reduce the virus transmission, it would also disrupt the mosquito control measures already in place.”

Dengue and Covid-19

Brady and a group of researchers from Beijing Normal University and the London School of Hygiene & Tropical Medicine (LSHTM) looked at monthly dengue cases between 2014 and 2020, using data from the World Health Organization (WHO). They covered 23 countries, 16 in Latin America and seven in Southeast Asia, as well as climate data such as temperature.

The researchers then looked at two measures of Covid-19 related disruption – public health and social measures (school and public transport closure and stay-at-home requirements) and human behavior through time spent at public and residential locations. They also incorporated the strength of the restrictions in lockdowns in different countries.

By combining this data, they showed that reduced time spent outdoors was linked with reduced dengue risk. Nine out of 11 countries in the Philippines, the Caribbean, and Central America had a full suppression of their dengue season in 2020, while other countries had a much-reduced season. Countries that set their pandemic restriction measures at the peak of the dengue season had a sharper decline of dengue cases.

The decrease in cases could also be linked to a lower rate of people seeking treatment for dengue, reduced availability of laboratory testing, and a higher potential of misdiagnosis, the researchers said. However, some countries like Sri Lanka predicted this could be a problem early in the pandemic and took measures, encouraging people to get diagnosed and seek treatment. Overall, this suggests that COVID-19 lockdowns also led to drops in dengue.

“Dengue control efforts are focused on or around the households of people who get sick. We now know that, in some countries, we should also be focusing measures on the locations they recently visited to reduce dengue transmission. For all the harm it has caused, this pandemic has given us an opportunity to inform new interventions and targeting strategies to prevent dengue,” Brady said.

In the long term, more routine measurement of the prevalence for dengue as well as a better understanding of how treatment-seeking behavior changes at different phases of dengue and COVID-19 epidemics will be important, the researchers wrote. That will require continued monitoring of the dengue trends in 2021 and beyond, including the collection of human mobility data.

The study was published in the journal The Lancet.

People with ADHD are more likely to be hoarders

Leave a reply
The living room of a compulsive hoarder. Credit: Wikimedia Commons.

Living with too much stuff inside a cramped apartment sounds like a staple of modern life, but some people do take it too far. Acquiring an excessive number of items and storing them in a chaotic way has a name: hoarding. It’s even recognized as a clinical mental health disorder and is generally associated with negative outcomes in terms of quality of life. But mental health disorders rarely occur in a complete vacuum and are often associated with other disorders. So it might not be surprising to learn that people diagnosed with attention-deficit/hyperactivity disorder (ADHD) are also more likely to be hoarders, according to a new study.

Pay attention to the clutter around you

Hoarding, a mental health condition that was formally recognized fairly recently, in 2013, when it was added to the DSM-5 (the American Psychiatric Association’s primary handbook for diagnosing mental health conditions), involves the compulsive need to keep objects, many of which can be described as mere trinkets or even trash such as old newspapers. Sometimes, the hoarding of animals is involved. In the hoarder’s mind, one question comes up again and again whenever encountering an object: What if I need it one day? But that rarely if ever happens. Instead, the hoarder’s home is turned into an unlivable warehouse, with barely enough room to move but always enough to spare for the next shiny thing.

Hoarders experience a great deal of anxiety when attempting to discard items and find it difficult to organize their possessions, which explains why some of their homes look like a claustrophobic tangled mess. This behavior can have serious deleterious effects for both the hoarder and their family members, including emotional distress, social isolation, financial problems, and even legal consequences — all depending upon the severity of the condition.

That’s because, just like many other psychiatric conditions, clinical hoarding is on a spectrum. Indeed, hoarding-like behavior is common among many healthy, well-adjusted individuals. And who here can say with a straight face they’ve never impulsively bought useless crap that is now just gathering dust somewhere in the house. We’re talking about extremes, though. At level 1, although the home is visibly cluttered, the doors, windows, and stairs are still accessible. By level 5, the most severe hoarding level, the degree of clutter is extreme, blocking virtually all living quarters. Rotting food, excessive bugs, and poor animal sanitation often infest such homes, raising serious health concerns for people and their pets.

Hoarding disorder is formerly associated with obsessive-compulsive disorder (OCD), but researchers at Anglia Ruskin University were curious to see if there was any connection with ADHD too. In the first leg of their study, the researchers asked patients from an adult ADHD clinic in the UK to fill in a series of questionnaires designed to gauge various traits and behaviors, including hoarding. A control group of similar age, gender, and education, which involved people not diagnosed with ADHD, had to answer the same questions.

This preliminary study found that about 20% of the ADHD participants reported significant hoarding symptoms compared to just 2% in the control group, which is close to the previously reported 2.5% prevalence of hoarding disorder in the general population. The patients with the most severe hoarding symptoms were also likely to suffer from anxiety and depression.

This is the first study that found an association between ADHD and hoarding disorder, so further research is warranted. This is also important from a therapy standpoint since hoarding disorder is very challenging to address, particularly because people with this condition are rarely aware they have a problem. Hoarders rarely recognize or accept that they may be suffering from a mental condition, or simply downplay it.

For instance, one significant aspect of this study is that the average age of the participants with ADHD and hoarding disorder was 30, with both genders equally represented. This challenges the popular imagery of an elderly female surrounded by a mountain of clutter and a dozen cats. Future interventions may be designed to address both ADHD and hoarding disorders in younger individuals before their effects precipitate as the patient ages.

The findings were reported in the Journal of Psychiatric Research.

The FDA finally approved a condom for anal sex. Here’s why it’s a good thing

Leave a reply

Whether you’re in a committed relationship or prone to the throws of lust (or both, we’re not judging), you need to protect yourself and your partner — which usually means using a condom.

Still, as humans tend to be, we’re not always careful. We like to experiment, we sometimes falter — and pick up sexually-transmitted diseases (STDs). Whatever the reason, condoms are a great way to stay safe and can be used by people of the appropriate age just about anywhere–and they can also be lots of fun. Now, there’s a new type of condom on the block.

A victory for all genders and denominations

There’s never been an approved condom specifically for anal intercourse. Until now, condoms on the market were only approved for vaginal intercourse, which omits a large section of our society.

Condoms for vaginal sex currently on the market are recommended for use during anal or oral intercourse by the Center for Disease Control – meaning they’re legally backed by a drug agency for one activity and informally deemed effective for another in what is known as ‘off-label’ use. But the US Food and Drug Administration (USFDA) has finally approved the first condom for anal sex: the ONE Male Condom.

The approval is seen as a victory for sexual health and especially important for the LGBTQ community, who, until now, have not had a condom aimed specifically at them. Courtney Lias, director of the USFDA’s Office of GastroRenal, Obstetrics-Gynecological, General Hospital, and Urology Devices, says:

“The risk of STI transmission during anal intercourse is significantly higher than during vaginal intercourse. The FDA’s authorization of a condom that is specifically indicated, evaluated, and labeled for anal intercourse may improve the likelihood of condom use during anal intercourse.” 

What’s different with this condom

The newly approved condom is a natural rubber latex sheath that covers the penis. It’s available in three different versions: standard, thin and fitted. The fitted condoms, available in 54 different sizes, incorporate a paper template to find the best condom size for each user to minimize leakage. Global Protection Corp, which makes the condom, stresses that during anal intercourse, users should employ a compatible lubricant with their condom and all other brands.

“We want people to have lots of sex — but we also want them to be empowered and informed,” said Davin Wedel, president of Global Protection Corp.

Scientists studied the safety and efficacy of the condom in a clinical trial comprised of 252 men who prefer sex with men and 252 men who prefer intercourse with women. All volunteers were between 18 and 54 years of age. 

Results show the total condom failure rate was 0.68% for anal sex and 1.89% for vaginal intercourse. Researchers defined the condom failure rate as the number of slippages, breakage, or both slippage and breakage events over the total number of sex acts recorded in a diary by participants.

Disappointingly, the trial didn’t calculate the STD baseline as too many variables (such as not wearing a condom) could cause infection during the trial. Therefore, the rate of STDs was not measured at the beginning of the study and compared with later data. Despite this, the trial center did allow participants to self-report any genital-based infections which could have resulted from the use of a different condom brand before or during tests.

The researchers from Emory University who were behind the study said an essential reason for the trial’s success was that volunteers used lubricant, which prevents slippage and breakage, and the inclusion of instructions.

Taken together, these findings suggest that health bodies should provide lubricant along with the billions of condoms distributed as part of HIV and STD prevention efforts to minimize failure. 

The USFDA will help get more condoms like these on the market

The USFDA is responsible for controlling and supervising food, tobacco, dietary supplements, prescription drugs, blood transfusions, medical devices, cosmetics, and animal & veterinary products. They achieve this by inspecting manufacturing premises and reviewing the safety and effectiveness of a product before a business can sell it on the market after it has undergone extensive clinical trials that can last for over a decade.

A rigid classification, under the terms of a De Novo, the submitting company, must prove that their product presents a ‘medium risk’ to humans. In contrast, under the 510(k) submission, an organization only has to show their device presents no more risk to human health than the approved equivalent product – even where the marketed product has been deemed dangerous. De Novo submissions are also more expensive than the cheaper 510(k).

Surprisingly, even though the ONE condom is already approved by the USFDA using the flexible 510(k) category for vaginal sex, the agency has cleared the new product for anal sex through the De Novo pathway. This fact certainly raises questions regarding the lack of equivalency between condoms used for vaginal sex and anal sex.

On a positive note, they have established special controls so that other devices can now show equivalence to the ONE condom using a 510(k) classification to receive quicker clearance without the need for clinical trials. 

In its press release, the USFDA said the green light could pave the way for more condom makers to apply for faster approval if they show equivalent results. They add that they expect authorization of the ONE Male Condom to help reduce the transmission of STDs, including HIV/AIDS in both anal and vaginal intercourse.

All approved condoms are an easy way to protect yourself

Experts remind all sexually-active couples that they can still use other approved condoms on the market during anal sex:

“This isn’t a groundbreaking advancement in my opinion. All condoms can (and should!) be used to make anal sex safer, so just because this one brand has FDA approval doesn’t make it any better than other condom brands on the market,” says obstetrician-gynecologist and author Jennifer Lincoln who wasn’t part of the trial, for PopSci. “Don’t let the ‘FDA approved’ label sway you when you are at the grocery store—the best condom to use for safe sex is the one you have access to and the one you will actually use.”

Still, this is a galvanizing moment for the LGBTQ movement.

“This authorization helps us accomplish our priority to advance health equity through the development of safe and effective products that meet the needs of diverse populations. This De Novo authorization will also allow subsequent devices of the same type and intended use to come to the market through the 510k pathway, which could enable the devices to get on the market faster,” Lias added in the USFDA statement.

It remains to be seen whether this will trigger a longer-term movement. In the meantime, stay safe.

Why chocolate is really, really bad for dogs

Leave a reply
The only good chocolate for dogs is a chocolate fur, like is majestic lab is rocking. Credit: Pixabay.

Unlike cats, which lack the ability to taste sweetness, dogs find chocolate just as appealing as humans. But while the dark treat can be a euphoric delight for us, it can be poisonous to canines.

That’s not to say that all dogs get poisoned by chocolate or that a candy bar is enough to necessarily kill your pet canine. The dose makes the poison. The weight of the dog also matters, so large canines should be able to handle a small amount of chocolate whereas smaller breeds might run into serious trouble.

Although you shouldn’t panic if your dog accidentally ingests chocolate, candy and other chocolate sweets should never be offered to dogs. Generally, you should treat chocolate as toxic to dogs and should make an effort to keep it away from them.

Why chocolate can be dangerous to dogs

Among the many chemical compounds found in dark chocolate and cocoa is theobromine. Formerly known as xantheose, theobromine is a bitter alkaloid compound that acts as a mild stimulant for the human body.

The consumption of theobromine is generally associated with positive effects, such as reduced blood pressure, improved focus and concentration, and enhanced mood. That’s in humans. In dogs, theobromine, as well as caffeine, raise the heart rate and can overstimulate the nervous system.

Because dogs can’t break down, or metabolize, theobromine as well as humans can, the compound is toxic to dogs, over a certain threshold, depending on their body weight.

Mild symptoms of chocolate toxicity occur when a canine consumes 20 mg of theobromine per kilogram per body weight. Cardiac symptoms occur at around 40 to 50 mg/kg and dangerous seizures occur at doses greater than 60 mg/kg.

This explains why a candy bar may cause a chihuahua (average weight 2 kg) to run in circles while Great Dane (average weight 70 kg) might feel just fine.

Darker, purer varieties of chocolate tend to be the most dangerous because they contain the highest concentration of theobromine. According to the USDA nutrient database, various chocolate/cocoa products contain the following amounts of theobromine per 100 grams;

  • Unsweetened cocoa powder: 2634 mg;
  • Baking chocolate (unsweetened): 1297 mg;
  • Dark chocolate (70% cocoa): 802 mg;
  • Mars Twix (twin bar): 39.9 mg;
  • White chocolate: 0 mg;

As a rule of thumb, chocolate poisoning in dogs generally occurs after the ingestion of 3.5g of dark chocolate for every 1kg they weigh, or 14g of milk chocolate for every kilogram.

Signs that your dog may be suffering from chocolate poisoning

Chocolate poisoning mainly affects the heart, central nervous system, and kidneys. The symptoms of theobromine toxicity usually appear within 6 to 12 hours after your dog eats too much chocolate and may last up to 72 hours. These include:

  • vomiting,
  • diarrhea,
  • restlessness,
  • increased urination,
  • tremors,
  • elevated or abnormal heart rate,
  • seizures,
  • and in extreme cases collapse and death.

Can chocolate kill dogs?

In short, yes. However, fatalities in dogs due to chocolate poisoning are very rare. According to the Veterinary Poisons Information Service from the U.S., out of 1,000 dog chocolate toxicity cases recorded in its database, only five dogs died. 

What do if your dog eats chocolate

If you caught your dog eating chocolate or you suspect this may have happened, it is best to call your veterinarian and ask for advice on how to proceed going forward. Based on your dog’s size and the amount and kind of chocolate ingested, the veterinarian may recommend monitoring your dog for any symptoms of poisoning or ask that you immediately come to the clinic.

If there are good reasons to believe potentially dangerous chocolate poisoning may be imminent, and as long as your pet consumed the chocolate less than two hours ago, the veterinarian may induce vomiting.

Sometimes, the dog may be given doses of activated charcoal, which helps to flush toxins out of the body before they are absorbed into the bloodstream.

In very extreme cases of poisoning, the veterinarian might administer medications and/or intravenous fluids to provide additional treatment.

Keep chocolate away from dogs

There’s no reason to believe chocolate isn’t as tasty to dogs as it is to humans. Unfortunately, many dog owners are ignorant to the fact that chocolate can poison their pets and intentionally offer chocolate snacks as a treat.

Usually, this isn’t a problem for very large breeds when they ingest small amounts of chocolate, but smaller dogs can suffer greatly and even die in extreme cases due to theobromine poisoning.

If you are aware that chocolate can poison your pet, you have no excuse to keep sweets accessible. It is advisable to keep any chocolate items on a high shelf, preferably in a closed-door pantry. Guests and children should be kindly reminded that chocolate is bad for dogs and that they shouldn’t offer chocolate treats regardless of how much the pet begs for them.

Most chocolate poisoning in dogs occurs around major holidays such as Christmas, Easter, or Valentine’s Day, so these are times when you should be extra careful. 

Gut bacteriophages associated with improved cognitive function and memory in both animals and humans

Leave a reply

A growing body of evidence has implicated gut bacteria in regulating neurological processes such as neurodegeneration and cognition. Now, a study from Spanish researchers shows that viruses present in the gut microbiota can also improve mental functions in flies, mice, and humans.

Credit: CDC.

They easily assimilate into their human hosts — 8% of our DNA consists of ancient viruses, with another 40% of our DNA containing genetic code thought to be viral in origin. As it stands, the gut virome (the combined genome of all viruses housed within the intestines) is a crucial but commonly overlooked component of the gut microbiome.

But we’re not entirely sure what it does.

This viral community is comprised chiefly of bacteriophages, viruses that infect bacteria and can transfer genetic code to their bacterial hosts. Remarkably, the integration of bacteriophages or phages into their hosts is so stable that over 80% of all bacterial genomes on earth now contain prophages, permanent phage DNA as part of their own — including the bacteria inside us humans. Now, researchers are inching closer to understanding the effects of this phenomenon.

Gut and brain

In their whitepaper published in the journal Cell Host and Microbe, a multi-institutional team of scientists describes the impact of phages on executive function, a set of cognitive processes and skills that help an individual plan, monitor, and successfully execute their goals. These fundamental skills include adaptable thinking, planning, self-monitoring, self-control, working memory, time management, and organization, the regulation of which is thought, in part, to be controlled by the gut microbiota.

The study focuses on the Caudovirales and Microviridae family of bacteriophages that dominate the human gut virome, containing over 2,800 species of phages between them.

“The complex bacteriophage communities represent one of the biggest gaps in our understanding of the human microbiome. In fact, most studies have focused on the dysbiotic process only in bacterial populations,” write the authors of the new study.

Specifically, the scientists showed that volunteers with increased Caudovirales levels in the gut microbiome performed better in executive processes and verbal memory. In comparison, the data showed that increased Microviridae levels impaired executive abilities. Simply put, there seems to be an association between this type of gut biome and higher cognitive functions.

These two prevalent bacteriophages run parallel to human host cognition, the researchers write, and they may do this by hijacking the bacterial host metabolism.

To reach this conclusion, the researchers first tested fecal samples from 114 volunteers and then validated the results in another 942 participants, measuring levels of both types of bacteriophage. They also gave each volunteer memory and cognitive tests to identify a possible correlation between the levels of each species present in the gut virome and skill levels.

The researchers then studied which foods may transport these two kinds of phage into the human gut -results indicated that the most common route appeared to be through dairy products.

They then transplanted fecal samples from the human volunteers into the guts of fruit flies and mice – after which they compared the animal’s executive function with control groups. As with the human participants, animals transplanted with high levels of Caudovirales tended to do better on the tests – leading to increased scores in object recognition in mice and up-regulated memory-promoting genes in the prefrontal cortex. Improved memory scores and upregulation of memory-involved genes were also observed in fruit flies harboring higher levels of these phages.

Conversely, higher Microviridae levels (correlated with increased fat levels in humans) downregulated these memory-promoting genes in all animals, stunting their performance in the cognition tests. Therefore, the group surmised that bacteriophages warrant consideration as a novel dietary intervention in the microbiome-brain axis.

Regarding this intervention, Arthur C. Ouwehand, Technical Fellow, Health and Nutrition Sciences, DuPont, who was not involved in the study, told Metafact.io:

“Most dietary fibres are one way or another fermentable and provide an energy source for the intestinal microbiota.” Leading “to the formation of beneficial metabolites such as acetic, propionic and butyric acid.”

He goes on to add that “These so-called short-chain fatty acids may also lower the pH of the colonic content, which may contribute to an increased absorption of certain minerals such as calcium and magnesium from the colon. The fibre fermenting members of the colonic microbiota are in general considered beneficial while the protein fermenting members are considered potentially detrimental.”

It would certainly be interesting to identify which foods are acting on bacteriophages contained within our gut bacteria to influence cognition.

Despite this, the researchers acknowledge that their work does not conclusively prove that phages in the gut can impact cognition and explain that the test scores could have resulted from different bacteria levels in the stomach but suggest it does seem likely. They close by stating more work is required to prove the case.

Exposure to air pollution could be a cause of ADHD in children

Leave a reply

While genetics play a big role, many other factors have been speculated to cause attention deficit hyperactivity disorder (ADHD) – from eating too much sugar to watching TV. Now, researchers have found that high levels of air pollution and limited access to green areas can also increase the risk of developing the condition.

Image credit: Wikipedia Commons.

ADHD is a common neurodevelopmental condition in children, which sometimes continues in adulthood. It’s a complex condition, difficult to diagnose, and with no cure. If left unchecked, ADHD can impact children’s performance at school and their relationships with parents and peers . It’s more common in boys than girls and it affects 1 in 20 children.

The disorder is generally diagnosed during the first years of school but it can manifest differently from child to child. Its cause, however, has been a subject of debate among researchers. In 2018, a study identified regions of the DNA associated with ADHD, for instance. But scientists have also been studying other factors, with no clear answers on many of them so far.

It seems like a lot of things could be responsible for ADHD, and the latest to blame is air pollution. According to previous research, it may cause ADHD through induced systemic oxidative stress, with disturbs brain development, leading to cognitive deficits. Noise exposure can also increase stress, with is associated with psychological disorders such as hyperactivity. However, results from previous research have so far been inconsistent or limited.

In a new study, researchers at the Barcelona Institute for Global Health (ISGlobal) looked at the links between environmental exposures (greenness, air pollution and noise) in early life and later ADHD incidence – using environmental exposure metrics in combination with a population-based birth cohort linked with administrative data.

“We observed that children living in greener neighborhoods with low air pollution had a substantially decreased risk of ADHD. This is an environmental inequality where, in turn, those children living in areas with higher pollution and less greenness face a disproportionally greater risk”, lead author Matilda van den Bosch said in a statement.

ADHD and air pollution

For the study, the researchers used birth data from the metropolitan area of Vancouver, Canada from 2000 to 2001 and also retrieved data on ADHD cases from hospital records. They estimated the percentage of green spaces in the participants’ neighborhoods as well as the levels of air and noise pollution, using exposure models.

The study identified a total of 1,217 ADHD cases, which represents 4.2% of the sampled population. The participants living in areas with a larger percentage of vegetation had a lower risk of ADHD. More specifically, the study showed that a 12% increase in vegetation was linked with a 10% drop in the risk of having ADHD.

The opposite associated was observed with air pollution. The participants who had higher exposure to PM2.5 (fine particulate matter) had a higher risk of ADHD. Specifically, every 2.1 microgram increase in the levels of PM2.5 meant an 11% increase in the risk of ADHD. No link was found between noise pollution, NO2, and ADHD.

“Our findings also show that the associations between PM2.5 and ADHD were attenuated by residential green space and vice versa as if the beneficial effects of vegetation and the harmful effects of PM2.5 neutralized each other,” Weiran Yuchi, a researcher at the University of British Columbia and first author of the study, said in a statement.

The study was published in the journal Environment International.

In research studies and in real life, placebos have a powerful healing effect on the body and mind

Leave a reply
The concept of placebos – which are sometimes called “sugar pills” – has been around since the 1800s. Image credits: Sharon McCutcheon.

Did you ever feel your own shoulders relax when you saw a friend receive a shoulder massage? For those of you who said “yes,” congratulations, your brain is using its power to create a “placebo effect.” For those who said “no,” you’re not alone, but thankfully, the brain is trainable.

Since the 1800s, the word placebo has been used to refer to a fake treatment, meaning one that does not contain any active, physical substance. You may have heard of placebos referred to as “sugar pills.”

Today, placebos play a crucial role in medical studies in which some participants are given the treatment containing the active ingredients of the medicine, and others are given a placebo. These types of studies help tell researchers which medicines are effective, and how effective they are. Surprisingly, however, in some areas of medicine, placebos themselves provide patients with clinical improvement.

As two psychologists interested in how psychological factors affect physical conditions and beliefs about mental health, we help our patients heal from various threats to well-being. Could the placebo effect tell us something new about the power of our minds and how our bodies heal?

Real-life placebo effects

Today, scientists define these so-called placebo effects as the positive outcomes that cannot be scientifically explained by the physical effects of the treatment. Research suggests that the placebo effect is caused by positive expectations, the provider-patient relationship and the rituals around receiving medical care.

Depression, pain, fatigue, allergies, irritable bowel syndrome, Parkinson’s disease and even osteoarthritis of the knee are just a few of the conditions that respond positively to placebos.

Despite their effectiveness, there is stigma and debate about using placebos in U.S. medicine. And in routine medical practice, they are rarely used on purpose. But based on new understanding of how non-pharmacological aspects of care work, safety and patient preferences, some experts have begun recommending increasing the use of placebos in medicine.

The U.S. Food and Drug Administration, the organization that regulates which medicines are allowed to go to the consumer market, requires that all new medicines be tested in randomized controlled trials that show they are better than placebo treatments. This is an important part of ensuring the public has access to high-quality medications.

But studies have shown that the placebo effect is so strong that many drugs don’t provide more relief than placebo treatments. In those instances, drug developers and researchers sometimes see placebo effects as a nuisance that masks the treatment benefits of the manufactured drug. That sets up an incentive for drug manufacturers to try to do away with placebos so that drugs pass the FDA tests.

Placebos are such a problem for the enterprise of drug development that a company has developed a coaching script to discourage patients who received placebos from reporting benefits.

Treating depression

Prior to the COVID-19 pandemic, about 1 in 12 U.S. adults had a diagnosis of depression. During the pandemic, those numbers rose to 1 in 3 adults. That sharp rise helps explain why US$26.25 billion worth of antidepressant medications were used across the globe in 2020. https://www.youtube.com/embed/REaiu-7wRvs?wmode=transparent&start=0 Brain-imaging studies show that the brain has an identifiable response to the expectations and context that come with placebos.

But according to psychologist and placebo expert Irving Kirsch, who has studied placebo effects for decades, a large part of what makes antidepressants helpful in alleviating depression is the placebo effect – in other words, the belief that the medication will be beneficial.

Depression is not the only condition for which medical treatments are actually functioning at the level of placebo. Many well-meaning clinicians offer treatments that appear to work based on the fact that patients get better. But a recent study reported that only 1 in 10 medical treatments sampled met the standards of what is considered by some to be the gold standard of high quality evidence, according to a grading system by an international nonprofit organization. This means that many patients improve even though the treatments they receive have not actually been proved to be better than the placebo.

How does a placebo work?

The power of the placebo comes down to the power of the mind and a person’s skill at harnessing it. If a patient gets a tension headache and their trusted doctor gives them a medicine that they feel confident will treat it, the relief they expect is likely to decrease their stress. And since stress is a trigger for tension headaches, the magic of the placebo response is not so mysterious anymore.

Now let’s say that the doctor gives the patient an expensive brand-name pill to take multiple times per day. Studies have shown that it is even more likely to make them feel better because all of those elements subtly convey the message that they must be good treatments.

Part of the beauty of placebos is that they activate existing systems of healing within the mind and body. Elements of the body once thought to be outside of an individual’s control are now known to be modifiable. A legendary example of this is Tibetan monks who meditate to generate enough body heat to dry wet sheets in 40-degree Fahrenheit temperatures.

A field called Mind Body Medicine developed from the work of cardiologist Herbert Benson, who observed those monks and other experts mastering control over automatic processes of the body. It’s well understood in the medical field that many diseases are made worse by the automatic changes that occur in the body under stress. If a placebo interaction reduces stress, it can reduce certain symptoms in a scientifically explainable way.

Placebos also work by creating expectations and conditioned responses. Most people are familiar with Pavlovian conditioning. A bell is rung before giving dogs meat that makes them salivate. Eventually, the sound of the bell causes them to salivate even when they do not receive any meat. A recent study from Harvard Medical School successfully used the same conditioning principle to help patients use less opioid medication for pain following spine surgery.

Furthermore, multiple brain imaging studies demonstrate changes in the brain in response to successful placebo treatments for pain. This is excellent news, given the ongoing opioid epidemic and the need for effective pain management tools. There is even evidence that individuals who respond positively to placebos show increased activity in areas of the brain that release naturally occurring opioids.

And emerging research suggests that even when people know they are receiving a placebo, the inactive treatment still has effects on the brain and reported levels of improvement.

Placebos are nontoxic and universally applicable

In addition to the ever-increasing body of evidence surrounding their effectiveness, placebos offer multiple benefits. They have no side effects. They are cheap. They are not addictive. They provide hope when there might not be a specific chemically active treatment available. They mobilize a person’s own ability to heal through multiple pathways, including those studied in the field of psychoneuroimmunology. This is the study of relationships between the immune system, hormones and the nervous system.

By defining a placebo as the act of setting positive expectations and providing hope through psychosocial interactions, it becomes clear that placebos can enhance traditional medical treatments.

Using placebos to help people in an ethical way

The placebo effect is recognized as being powerful enough that the American Medical Association considers it ethical to use placebos to enhance healing on their own or with standard medical treatments if the patient agrees to it.

Clinically, doctors use the principles of placebo in a more subtle way than it is used in research studies. A 2013 study from the U.K. found that 97% of physicians acknowledged in a survey having used some form of placebo during their career. This might be as simple as expressing a strong belief in the likelihood that a patient will feel better from whatever treatment the doctor prescribes, even if the treatment itself is not chemically powerful.

There is now even an international Society for Interdisciplinary Placebo Studies. They have written a consensus statement about the use of placebos in medicine and recommendations for how to talk with patients about it. In the past, patients who improved from a placebo effect might have felt embarrassed, as if their ailment were not real.

But with the medical field’s growing acceptance and promotion of placebo effects, we can envision a time when patients and clinicians take pride in their skill at harnessing the placebo response.

Elissa H. Patterson, Clinical Assistant Professor of Psychiatry and Neurology, University of Michigan and Hans Schroder, Clinical Assistant Professor of Psychiatry, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Brain scan of dying man shows ‘life flashing before their eyes’

Leave a reply
Credit: Pixabay.

One of humanity’s never-ending quests since times immemorial is revealing what happens to us after we die. But although whether there’s an after-life or soul are the kind of questions science may never be able to answer satisfactorily, modern tools allow us to probe the next best thing: what goes on inside the human brain during its final fleeting moments.

While an 87-year-old man with epilepsy was strapped to a machine that scanned his brain, searching for signs of seizures, the patient, unfortunately, suffered a heart attack and died shortly after. But the man’s tragic death offered scientists the opportunity of a lifetime, allowing them to record brain activity 30 seconds prior to and after the patient’s heart stopped beating.

The recorded brain waves suggest that, as we die, we experience the same neural activity as during dreaming, recalling memories, or meditating. These high-cognitive functions could be a literal example of someone’s life flashing before their eyes, according to the authors of a new study published in Frontiers in Aging Neuroscience.

“We measured 900 seconds of brain activity around the time of death and set a specific focus to investigate what happened in the 30 seconds before and after the heart stopped beating,” said Dr. Ajmal Zemmar, a neurosurgeon at the University of Louisville, who led the study.

“Just before and after the heart stopped working, we saw changes in a specific band of neural oscillations, so-called gamma oscillations, but also in others such as delta, theta, alpha and beta oscillations.”

Gamma brain waves are the fastest brain oscillations and mainly occur when you’re highly alert and conscious. They’re associated with higher-order cognitive functions, being particularly active when concentrating, dreaming, and meditating, as well as when the brain is engaged in memory retrieval, information processing, and conscious perception.

Near-death experiences

These oscillations are often associated with memory flashbacks, and may explain anecdotal reports by people who have gone through near-death experiences, in which important life events are recalled in rapid succession. “These findings challenge our understanding of when exactly life ends and generate important subsequent questions, such as those related to the timing of organ donation,” Zemmar said.

Near-death experiences are surprisingly common, with a third of people who have come close to death reporting having experienced one. Common characteristics people report are feelings of contentment, psychic detachment from the body (such as out-of-body experiences), rapid movement through a long dark tunnel, and entering a bright light.

Neuroscientists Olaf Blanke and Sebastian Dieguez have previously proposed two types of near-death experiences. Type one is associated with the brain’s left hemisphere, featuring an altered sense of time and impressions of flying. Type two, involving the right hemisphere, is characterized by seeing or communicating with spirits, and hearing voices, sounds, and music.

It has always been unclear why there are different types of near-death experiences, but the fact that the brain goes into a sort of overdrive during our last moments alive could be telling. However, we should exercise caution because this is the first and single case when live brain activity was monitored during the process of dying in humans. The patient had suffered injury, seizures, and swelling, so any conclusion cannot be generalized for the entire population. Nevertheless, these limited findings suggest that our final moments on Earth may be pleasant and peaceful. 

“As a neurosurgeon, I deal with loss at times. It is indescribably difficult to deliver the news of death to distraught family members,” Zemmar said.

“Something we may learn from this research is: although our loved ones have their eyes closed and are ready to leave us to rest, their brains may be replaying some of the nicest moments they experienced in their lives.”

Scientists find neurons in the human brain that only respond to singing

Leave a reply
Credit: Pixabay.

Music and the human brain seem to be deeply intertwined, a bond that may have first appeared when the first australopithecine ancestor got up on her hind legs 4.4 million years ago and walked. This bipedal rhythm may have made our lineage particularly sensitive to musicality, so much so that we now know that the human brain has dedicated neural circuitry for processing and interpreting musical information.

In 2015, neuroscientists at MIT identified a population of neurons in the auditory cortex that responds specifically to music. In a new study that appeared today in the journal Current Biology, the same team of researchers led by Sam Norman-Haignere have identified specific neurons in the brain that light up only when we hear singing, but not other types of music.

“The work provides evidence for relatively fine-grained segregation of function within the auditory cortex, in a way that aligns with an intuitive distinction within music,” said Norman-Haignere, a former MIT postdoc who is now an assistant professor of neuroscience at the University of Rochester Medical Center.

The singing brain

For their original 2015 work, the scientists used functional magnetic resonance imaging (fMRI) to scan the brains of participants as they listened to a collection of 165 sounds. These included everyday sounds like a dog barking or traffic in a busy city, as well as different types of speech and music.

After analyzing the brain patterns using a novel interpretation technique for fMRI data, the researchers identified a neural population that responded differently to both music and speech.

However, fMRI –which detects the changes in blood oxygenation and flow that occur in response to neural activity while a person lies down inside a machine equipped with very powerful magnets — has its limitations. A much more precise method for recording electrical activity in the brain is electrocorticography (ECoG), which directly measures patterns of activity using electrodes implanted inside the skull. The obvious drawback is that this is highly invasive. Let’s just say there aren’t too many keen volunteers that would gladly have their skulls drilled for science — unless you already don’t have much to lose.

Electrocorticography is becoming relatively widely used to monitor patients with epilepsy who are about to undergo surgery to treat their seizures. This allows doctors to pinpoint the exact location in the brain where a patient’s seizures are originating, which can be different from person to person.

Some of these patients agreed to participate, and MIT researchers were able to gather data from them over several years. Many of the 15 participants involved in the study didn’t have electrodes fitted in their auditory cortex, but some did — and the insight they provided proved valuable. Using a novel statistical approach, the researchers were able to identify neural populations that were responsible for the electrical activity recorded by each electrode.

“When we applied this method to this data set, this neural response pattern popped out that only responded to singing,” Norman-Haignere says. “This was a finding we really didn’t expect, so it very much justifies the whole point of the approach, which is to reveal potentially novel things you might not think to look for.”

“There’s one population of neurons that responds to singing, and then very nearby is another population of neurons that responds broadly to lots of music. At the scale of fMRI, they’re so close that you can’t disentangle them, but with intracranial recordings, we get additional resolution, and that’s what we believe allowed us to pick them apart,” he added.

When ECoG data was combined with fMRI, the researchers were able to determine even more precisely the locations of the neural populations that responded specifically to signing, but not other kinds of music.

“The intracranial recordings in this study replicated our prior findings with fMRI and revealed a novel component of the auditory response that responded nearly exclusively to song,” Norman-Haignere told ZME Science.

These song-specific hotspots were found at the top of the temporal lobe, near regions that are selective for language and music. This suggests that song-specific populations of neurons likely respond to perceived pitch, so they might tell the difference between spoken words and musical vocalization, before sending this information to other parts of the brain for further processing.

These findings enrich our understanding of how the human brain responds to music. For instance, previous research showed music impacts brain function and human behavior, including reducing stress, pain and symptoms of depression, as well as improving cognitive and motor skills, spatial-temporal learning, and neurogenesis, which is the brain’s ability to produce neurons. 

But many mysteries still remain, which is why the MIT researchers plan to study infants’ neural response to music, in hopes of learning more about how brain regions tuned to music develop. 

“At present, we know very little about song-selective neural populations, in part because we just discovered them and in part because this type of data takes a long time to collect. Those are great questions that future research will hopefully shed some light on,” Norman-Haignere told ZME Science.

Playing Mahjong could boost mental health at old age

Leave a reply

Mahjong, a game of skill and luck played by four people using domino-like engraved tiles, is often referred to as China’s “national pastime”. Unlike many other popular leisure games, mahjong requires cooperation and strategy between players, which fosters the ideal forum for interaction between people. And according to a new study conducted at the University of Georgia, this engaging social interaction may boost mental health among Chinese elderly people, who are some of the most vulnerable people to depression in the world.

Credit: Pixabay.

The history of mahjong is somewhat contested, but the current consensus seems to be that it first appeared around Shanghai in the mid- to late-1800s. It quickly became popular in Shanghai and Beijing, then the entire country, and eventually among American expatriates that brought the game back to the United States, where it spread like wildfire in the 1920s.

It’s common for fans of the game to play mahjong with the same group of people for a long time, routinely meeting for game sessions. Some older Chinese people have had the same mahjong partners for decades. Even during the pandemic, the most dedicated players kept in touch by playing mahjong online.

The benefits of engaging in social activities for mental health have been widely reported, but such research has been mainly done in developed nations, such as the U.S. and Japan. To fill the gap, researchers led by Adam Chen, an associate professor of health policy and management at the University of Georgia, wanted to investigate the mental health impact of playing mahjong among elderly Chinese people.

The researchers analyzed survey data from nearly 11,000 Chinese people aged 40 years and older from the nationally representative China Health and Retirement Longitudinal Study. Depression symptoms were assessed for each participant and compared to the type and frequency of social participation, including visiting with friends, playing mahjong, participating in a sport or social club, and volunteering in the community.

As a whole, engaging in frequent social activities was associated with better mental health outcomes, playing mahjong was particularly associated with a positive effect. That’s not surprising. Studies looking at brain connectivity during social interaction have found that our brains react strongly to social cues, suggesting that our social networks and interactions also help shape the brain. Besides, talking to people can make you feel better, whereas loneliness can increase the level of cortisol and the level of stress, which can hamper brain activity.

Another 2019 study in England found cultural engagement — i.e. going to plays, movies, concerts, and museum exhibits — lowers the risk of developing depression. Studies also suggest that playing brain games can help in sharpening certain cognitive abilities such as planning, processing speed, and decision making.

“What is more surprising is that mahjong playing does not associate with better mental health among rural elderly respondents,” Chen said in a statement. “One hypothesis is that mahjong playing tends to be more competitive and at times become a means of gambling in rural China.”

Poor mental health is a huge burden on China, accounting for 17% of the global disease burden of mental disorders. These findings may offer a guide for policymakers looking to design interventions to improve mental health among older Chinese, which could also translate to Asian American communities.

“Social participation manifests itself in different formats within different cultural contexts,” said Chen.

“Older Asian Americans have a much higher proportion of suicidal thoughts than whites and African Americans,” he said. “Improving social participation among older Asian Americans may help to address this burden to the U.S. population health that has not received due attention.”

The findings appeared in the journal Social Science & Medicine.

A new problem from air pollution: It could be affecting sperm quality

Leave a reply

Air pollution doesn’t just kill millions prematurely every year, especially in developing countries, it also affects the human sex ratio at birth and cause birth defects. Now, a new study in China has found yet another problem, finding that chemicals or particles in the air may also target sperm quality — specifically sperm motility, the ability of sperm to move in the right direction.

Image credit: Wikipedia Commons.

Infertility is a big public health problem, affecting about 10% of all couples at reproductive age. Pure male factors, especially poor semen quality, account for 50% of all infertility cases, according to the World Health Organization. Evidence has also suggested recently a downward trend in semen quality, with a decline in sperm motility, and the causes are not entirely clear.

Genetic background plays a big part in poor semen quality, but the marked decline in sperm quality in recent years suggests there’s something else going on, and here’s where environmental factors enter. Studies have reported a link between particulate matter (PM) and semen quality, but so far, the connection has been rather inconsistent.

An international literature review published last year said there’s enough reason to believe that air pollution is affecting fertility in general. Fossil fuels have been found in people’s urine, semen, blood, and breast milk. Many of these pollutants are endocrine disruptors, altering the body’s hormonal systems.

In a new study, researchers from Tongji University in Shanghai explored the data records of almost 34,000 men, aged 34 on average, from 340 Chinese cities, all exposed to a varying degree of air pollution. Their wives got pregnant by using reproductive technology with their sperm between January 2013 and December 2019.

Pollution and sperm

With the data collected, the researchers looked for patterns in semen quality in relation to whether the participants had been exposed to amounts of PM smaller in diameter than 2.5 micrometers, between 2.5 and 10 micrometers and over 10 micrometers. This was done several moments before the patient’s visit to the hospital.

The researchers focused on sperm count, concentration and sperm motility. While they couldn’t find a direct link between air pollution and the first two factors, they did find that the more a patient was exposed to small PM, the lower the sperm total and progressive motility was. Progressive motility is the ability to swim forward and total motility is the ability to swim in general.

Specifically, there was an estimated 3.6% drop of sperm motility when exposed to PM smaller than 2.5 micrometers and a 2.4% decline when exposed to PM of 10 micrometers, the study showed. This means that different sizes of PM could have different effects on semen quality. The smaller the PM, the more likely it is to travel to the human lungs and potentially affect sperm quality.

The study showed that the effects of air pollution on sperm quality are more significant when the exposure occurs in the first part of the 90 days of sperm creation, known as spermatogenesis, instead of the other two phases. This could indicate that PM affects sperm on a genetic level. However, it’s all speculation at this point and further research will be needed to confirm this hypothesis.

“Poor sperm motility has raised global concern as a major cause of male infertility. Our findings add evidence that PM exposure during sperm motility development may contribute to reduced sperm motility. Although the estimated decrease in sperm motility was relatively small, it still resulted in significantly increased odds of asthenozoospermia (the medical term for reduced sperm motility),” the researchers wrote.

The study was published in the journal JAMA.

Even a 3-second workout every day can make you fitter and stronger

Leave a reply

Doctors and scientists are quick to point out that working out, even just for brief periods of time, can be very helpful for your health. But in a new study, a team of researchers really took that to the extreme: they wanted to see whether even just a few seconds of working out a day can make a difference. It did.

The team from the Edith Cowan University in Australia and the Niigata University of Health and Welfare in Japan recruited a group of healthy university students. They split them into two: 39 students performed a bicep curl at maximum effort for 3 seconds a day, 5 days a week, over 4 weeks. Meanwhile, 13 other students did not exercise over the same period.

The workout group performed three different bicep curl variations: isometric (with the weight parallel to the ground), concentric (raising the weight), and eccentric (lowering the weight). They worked out with a special resistance machine. Overall, over the course of the four weeks, they worked out for just 60 seconds — but the results were visible.

The researchers measured the maximum voluntary contraction (MVC), a common measure of muscle strength before and after the regimen. Surprisingly, the students in the workout group exhibited a notable change, while for the control group, there was no difference.

The workout group exhibited improvements for all types of bicep variations (12.8% for concentric strength, 10.2% for isometric strength, and 12.2% for eccentric strength). Overall, the muscle strength improved by 11.5%. However, when they looked at other measures of strength, the results were less impressive.

The study authors note that the 3-second eccentric MVC of the elbow flexors performed increased isometric, concentric, and eccentric MVC torque by more than 10%. “It was concluded that the daily 3-second eccentric MVC over 20 days produced more potent effects than isometric or concentric MVC on neuromuscular adaptations,” the researchers write in the study.

The muscle thickness did not increase significantly, the researchers write, which was in line with what they were expecting. In addition, the study’s sample size was small, which is an important limitation. Nevertheless, the results are important and are an indication that even short (very short) workout training sessions can make a difference.

The results are expected to be particularly significant for beginners, people who have never really worked out or haven’t worked out for a while. It could also help fight muscle degradation in old age. Furthermore, researchers say the same effect could be observed in other muscle groups, though there is a need for further studies to confirm this.

The study was published in the journal Scandinavian Journal of Medicine and Science in Sports.