Tag Archives: trauma

Trauma may cause cognitive decline in adults

Credit: Pixabay.

Trauma suffered both in childhood and adulthood may lead to significant cognitive decline later in life, according to a new study that highlights the importance of therapy and other interventions in order to stave off mental health problems.

“We found that the more adverse events experienced, such as your parents’ divorce or a parent dying, the greater the cognitive decline,” said Margie Lachman, professor of psychology at Brandeis University and co-author of the new study.

It’s no secret that traumatic stress can provoke long-lasting changes in key brain areas involved in stress response, such as the amygdala, hippocampus, and prefrontal cortex.

Previously, neuroscientists found that patients with post-traumatic stress disorder (PTSD) had smaller hippocampal and anterior cingulate volumes, increased amygdala function, and decreased medial prefrontal/anterior cingulate function. In addition, patients with PTSD show increased cortisol and norepinephrine responses to stress.

In terms of behavior and symptoms, PTSD is strongly associated with disruptions in one’s ability to have healthy, satisfying relationships and a low tolerance for uncertainty and adversity.

In their new study, Lachman and graduate student Kristin Lynch investigated potential associations between trauma and cognition.

The researchers combed through the Midlife Development in the U.S. (MIDUS) study, a national longitudinal study of health and well-being in adulthood, which involved 2,500 adults, ages 28 to 84.

The participants had to complete a questionnaire that listed 12 potentially traumatic events and investigated how these events negatively affected them. Examples of potentially traumatic events include divorce or death of a parent during childhood, emotional or physical abuse, parental alcohol or drug addiction, military combat experience, and losing a home to fire, flood, or natural disaster.

Each subject also had to complete tests that assessed their cognitive abilities in two key areas: executive functioning (focusing attention, planning, problem-solving, and multitasking) and episodic memory (remembering recently learned information).

The cognitive test results were compared to those from participants who claimed they hadn’t experienced traumatic events.

Not surprisingly, those who said they experienced trauma in the past exhibited a greater decline in both executive functioning and episodic memory.

The researchers also found that exposure to trauma later in life led to a greater decline in executive functioning than those who suffered from childhood trauma. There were no significant differences in episodic memory decline between those who experienced trauma earlier or later in life.

According to the researchers, trauma may lead to impaired cognitive performance due to the effects of stress and depression. Trauma is also linked to metabolic disease, inflammation, and disruption of the body’s immune system, which are also known to harm the brain’s performance.

The researchers stress that the effects of trauma on the brain vary on a person-to-person basis and for some they can be quite subtle. “It might not feel like there’s an effect on your day-to-day functioning,” Lynch said.

The findings appeared in the Journal of Traumatic Stress.

Violent trauma makes children show signs of brain and genetic aging

Experiencing violence and abuse in early life can lead to faster aging later in life, both mentally and physically.

Image via Pixabay.

A new study from the American Psychological Association explains that experiencing trauma associated with violence early on impacts the way our bodies age throughout our lives. The researchers note this process happens in three indicators of biological aging: onset of puberty, the cellular aging process, and brain development.

Hard start

“Exposure to adversity in childhood is a powerful predictor of health outcomes later in life — not only mental health outcomes like depression and anxiety, but also physical health outcomes like cardiovascular disease, diabetes, and cancer,” said Katie McLaughlin, PhD, associate professor of psychology at Harvard University and senior author of the study.

“Experiencing violence can make the body age more quickly at a biological level, which may help to explain that connection.”

It’s not the first time researchers are looking into the link between a hard childhood and the speed of aging. However, they looked at several indicators of biological aging and different types of adversity together (such as violence, neglect, poverty, abuse. They found a link, but due to their structure, we couldn’t exactly tell what was causing what.

To get a clearer idea of what’s happening, the team performed a meta-analysis of over 80 studies (more than 116,000 participants in total) and teased apart threat-related adversity, such as abuse and violence, and deprivation-related adversity, such as neglect or poverty.

Children who experienced threat-related trauma were more likely to enter puberty early, the team explains, and show signs of accelerated cellular aging. One of the most telling signs of this latter type of aging was shortened telomeres, which are protective caps placed on the ends of DNA strands to keep them from breaking down. Children who experienced poverty or neglect, meanwhile, didn’t show early signs of aging.

The team then also looked at a further 25 studies (over 3,250 participants in total) to see how adversity in early life impacted later brain development. They did find it was associated with reduced cortical thickness, which is a sign of aging. Our cortices house most of our brain’s processing power and virtually all its higher functions, and are known to degrade as we get older.

However, the team did find that the exact type of adversity we experience as kids leads to thinning in a different area of the cortex. Trauma and violence affected the ventromedial prefrontal cortex in particular, which is involved in social and emotional processing. Deprivation was more often associated with thinning in the frontoparietal, default mode, and visual networks (involved in processing sensory information and other cognitive tasks).

As to why this process takes place, McLaughlin believed that maturing earlier could help ensure your survival in a violent, threat-filled environment. Alternatively, reaching puberty more early in such a setting would allow more people to possibly procreate. So they do have their uses — but in the modern world, they can lead to health complications later in life.

All of the studies worked with children and adolescents under age 18.

“The fact that we see such consistent evidence for faster aging at such a young age suggests that the biological mechanisms that contribute to health disparities are set in motion very early in life. This means that efforts to prevent these health disparities must also begin during childhood,” McLaughlin said.

The next step for the team is to investigate whether treatments aimed at children who have experienced trauma can help prevent or slow down this pattern of early aging.

The paper “Biological Aging in Childhood and Adolescence Following Experiences of Threat and Deprivation: A Systematic Review and Meta-Analysis” has been published in the journal Psychological Bulletin.

First identified biomarker for PTSD could hold the key to treating the disorder

New research from the Centre for Addiction and Mental Health (CAMH) and the Canadian Institutes of Health Research (CIHR) may lead to the first clinical diagnostic tool for post-traumatic stress disorder (PTSD) and novel, reliable treatments.

Art therapy mask created at the National Intrepid Center for Excellence (NICoE) depicts demons coming out of the brain of a PTSD patient, a serviceman, who created it.
Image credits Department of Defense / Katie Lange.

PTSD is a debilitating mental health condition that can be triggered by either experiencing or witnessing extreme trauma. However, there are no clinical diagnostic tools for PTSD today, and treatment options are limited and of limited efficacy.

A new study into the physiological roots of PTSD and preventive measures against it could set that right, however. The authors report identifying a protein complex that’s elevated in the bodies of PTSD patients. The team developed a peptide compound that targets and disrupts this protein, which has proven effective in preventing the formation or recall of traumatic memories in early tests in mice.

Chemical bliss

“The discovery of the Glucocorticoid Receptor-FKBP51 protein complex provides a new understanding of molecular mechanisms underlying PTSD,” said Dr. Fang Liu, the study’s corresponding author. “We believe this protein complex normally increases after severe stress, but in most cases, levels soon go back to baseline levels.”

“However, in those who develop PTSD, the protein complex remains persistently elevated, and so this could be a blood-based biomarker for PTSD as well as being a target for pharmacological treatment.”

Back in 1915, English psychologist Charles Myers coined the term “shell shock” to describe the state of soldiers who were involuntarily shivering, crying, fearful, and experienced constant intrusions of distressing memories following their service in the hellscapes of World War One. “Shell shock” isn’t in current psychiatric use any longer as it has been rolled into the wider-ranging concept of PTSD. However, it can be seen as its intellectual forerunner.

We now know that such symptoms aren’t limited to army personnel. Victims of violent or sexual assault also often develop PTSD, as do survivors of non-assault based trauma (such as natural disasters), albeit less often.

PTSD is characterized by persistent and intrusive memories or nightmares of the traumatic event, heightened levels of anxiety and vigilance, general emotional unresponsiveness, and persistent avoidance of stimuli related to the trauma. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) lists 17 different symptoms of PTSD, and requires at least one (of the five) re-experiencing symptoms, at least three (of seven) avoidance symptoms, and at least two (of five) arousal symptoms to be present for one month for a diagnosis to be made.

Some of the other masks created at NICoE. Patients are encouraged to express their experience through the masks. Many depict a split sense of self or chaotic thought patterns.
Image credits Department of Defense / Katie Lange.

It’s still a very current problem. The team examined statistics from 24 countries and found that Canada currently has the highest prevalence of PTSD among the lot. Around 9.2% of Canadians will develop PTSD during their lifetimes, they explain. A 2017 study estimated that around 6.8% of Americans will develop PTSD during their lifetime.

The authors of the new paper report that individuals with PTSD have heightened levels of a complex protein formed from the glucocorticoid receptor (GR) and the FKBP51 binding protein compared to healthy controls, people who were exposed to trauma without developing PTSD, and patients with major depressive disorders. Fear-conditioned mice also showed heightened levels of this protein complex, they add. These findings strongly suggest that the complex is a mediator for the disorder.

In order to validate their findings, the team designed the peptide TAT-GRpep (think of peptides as being chunks of protein) that binds to and disrupts the function of the GR-FKBP51 complex. TAT-GRpep works by binding to the GR, effectively taking up the spot that the protein complex needs to bind to in order to elicit a response in the body. They tested this peptide on lab mice and report that it was “able to decrease GR-FKBP51 complex levels in both blood and brain tissue from mice,” suggesting that it could also prove effective in humans.

“Because our interfering peptide can block the consolidation of fear memories, we propose that it or a therapeutic analog could be given to patients exposed to severe trauma, as a prophylaxis against the future emergence of PTSD,” the paper reads. “The protein complex could also be a treatment target for established PTSD symptoms and as a biochemical diagnostic marker for PTSD.”

“Any of these advances would significantly improve on current clinical approaches to this important brain disorder.”

Dr. Liu and her team plan to further test and refine the peptide before conducting human clinical trials.

The paper “The glucocorticoid receptor–FKBP51 complex contributes to fear conditioning and posttraumatic stress disorder” has been published in the Journal of Clinical Investigation.

Credit: Pixabay.

The 2016 election was so traumatic it caused PTSD symptoms in 1 in 4 young adults

The 2016 Presidential election, which saw Donald Trump rise to power, was marked by some of the most divisive campaigns in American history. So much so that for some young adults, the experience was genuinely traumatic. According to psychologists, one in four young adults experienced symptoms similar to those seen in post-traumatic stress disorder.

Credit: Pixabay.

Credit: Pixabay.

Melissa Hagan, an assistant professor of psychology at San Francisco State University, noticed that in the months following the election, her students appeared significantly affected. Surveys conducted at the time also confirmed some part of the population experienced psychological stress in the aftermath of the election.

Looking to put a finger on how much stress the 2016 election caused, Hagan and colleagues, enlisted 769 students who were taking a psychology course at Arizona State University. The participants included a variety of racial and ethnic backgrounds, as well as religious and political identities.

Using a standard psychological assessment tool called the Impact of Event Scale (IES), researchers surveyed how many of the students were impacted by the election in such a way that it might lead to diagnosable PTSD.

According to the results, 25% of the students crossed the PTSD threshold. Another frightening result was that the average score of students was comparable to those obtained by witnesses of a mass shooting seven months after the event.

“What we were interested in seeing was, did the election for some people constitute a traumatic experience? And we found that it did for 25 percent of young adults,” Hagan said in a statement.

Researchers also determined that 37.2% of students were completely dissatisfied with the election results and 18.5% were completely satisfied — everyone else was in the middle. When the researchers gauged the extent to which the students were upset by the results, they found that 39% of students were extremely upset, while 28.5% reported not feeling upset at all. About 24.2% of the students said their relationships were impacted negatively by the election, 10.4% said there was some negative impact, and 65% experienced no impact at all.

Some students were more affected than others. Black and nonwhite Hispanic participants scored higher on the PTSD assessment than their white counterparts. Females scored nearly 45% higher than males, and Democrats scored more than two and a half times higher than Republicans, the authors reported in the Journal of American College Health.

It’s not clear whether the traumatic effects of the 2016 elections will carry on over the long-term, as the psychological assessment of the students only happened once. The high prevalence of PTSD symptoms, however, should warrant school mental health staff to be more mindful of the political environment which their students are experiencing, apart from the usual stressors. And given the level of stress measured by the researchers, it wouldn’t be all that surprising to see some of the negative effects on people’s mental health last for years.

As to what made this election particularly traumatic, the shock of Donald Trump’s win and the hate-centered divisive narrative seem to have played important roles.

“There was a lot of discourse around race, identity and what makes a valuable American. I think that really heightened stress for a lot of people,” said Hagan.

Credit: Pixabay.

What doesn’t kill you really makes you stronger: post-PTSD individuals experience mental growth

Credit: Pixabay.

Credit: Pixabay.

A traumatic experience can ruin a person’s life — but it may very well also do the opposite. Most people recover quickly from post-traumatic stress disorder (PTSD) and report having a better mental health than before the traumatic episode. Now, a new study suggests that this happens because the trauma triggers a sort of mental training that primes survivors for the next such event. In doing so, the survivors gain better control over their own minds and can experience significant mental growth.

Trauma — training the mind for resilience

For the study, two groups, each comprising of 48 undergraduates, were tasked with playing various word games by researchers at Bard College and the University of Cambridge. Among the participants, some had experienced relatively significant trauma, such as witnessing or experiencing an accident, violence, death in the family, and so on.

During one task, the participants had to view a set of 60 pairs of words, which consisted of a neutral word (for instance, “violin”) and either a neutral or negative response word (“street” or “corpse”). The participants were allowed to go through three training cycles before they had to recall at least half of the response words. After the training, the real experiment began: a so-called “Think/No-Think” trial.

What this means is that when a cue word was flashed on a screen in the color green, the participants had to say the response word as fast as possible. However, if the cue word appeared in red, they had to avoid saying the word or even thinking about it for the next four seconds. Finally, the researchers put a twist on the recall tests by introducing a new semantic cue word plus the initial letter of the response word (e.g. “anatomy c____”, which should read as “anatomy corpse”). This latter test was designed to sidestep the original cue-target association and assess memory inhibition.

The research team found that people in both high and low trauma groups were just as good at the initial word association test. However, those in the high trauma group were significantly better at the “No Think” trials, demonstrating a more robust ability to forget specific words on request. This performance was equally good for both neutral and negative words, suggesting this is a generalized suppression skill.

The ability to inhibit certain memories may help people who have experienced severe trauma to become more resilient. This general inhibitory control mechanism could also help post-PTSD individuals to suppress unwanted emotions and actions, making them more disciplined, focused, and daring in other aspects of their life.

The findings have important implications for the treatment of PTSD. Standard cognitive-behavioral therapies for PTSD encourage patients to face their traumas, the idea being that remembering traumatic events will make them less distressing. While the authors agree that this certain therapy is important, their findings suggest that it may also be beneficial to suppress certain memories. What’s more, it may be that patients who don’t respond to standard treatment and develop chronic PTSD may have deficits in such inhibitory control.

“Our findings suggest that traumatic experiences – as horrible as they may be – might naturally contribute to the adaptation of cognitive control skills, thereby improving survivors’ later resilience, at least [for] those who experienced only moderate levels of trauma,” wrote the authors in the Journal of Experimental Psychology. 

What doesn’t kill you, makes your life shorter: Baboons with rough childhoods die earlier

Studies show that childhood trauma like abuse, neglect, physical accidents and other hallmarks put people at greater risk of dying prematurely once in adulthood. A rough childhood is associated with heart disease, diabetes, and addiction later in life, even though the stressful events have subsided. Generally, what doesn’t kill you makes your life shorter. This is true for baboons as well, according to researchers at Duke University, University of Notre Dame and Princeton University.

A four-month old infant baboon rides on its mother's back near Amboseli National Park in Kenya. Credit: Susan Alberts, Duke University

A four-month old infant baboon rides on its mother’s back near Amboseli National Park in Kenya. Credit: Susan Alberts, Duke University

When wild baboon younglings go through misfortunes early in their lives, such as experiencing a merciless drought or losing their mother, their lifespan is significantly reduced. Compared to more fortunate peers, the traumatized baboons can live up to ten years less.

The researchers produced their findings with the help of a long-term study of 196 wild female baboons which were monitored nearly daily between 1983 and 2013.

The life of a baboon isn’t easy. Risks like famine, overcrowding, predators, droughts and human activity take their toll. But depending on when and where they were born, some baboons had it better early in life.

In total, six sources of adversity in early that reduce lifespan were identified. These include little rainfall or losing a mother. Three-quarters of the baboons had at least one of the six early risk factors, and 15 percent had three or more. The most vulnerable were those young baboons who lost their mothers before age four, or whose next-born sibling arrived before they were fully weaned.

“Females who got a good start in life, who were born of high-ranking mothers when there was a lot of food around, lived a lot longer than females who did not get a good start in life,” says Joan Silk, an evolutionary anthropologist at Arizona State University who was not involved in the study. “Although it is intuitive that this might be the case, no one had ever shown this before. No one had the kind of the data that you need to show this,” she adds.

Some psychologists suggest that childhood trauma leads to poor lifestyle choices later in life like smoking, binge eating, drugs and so on. Exposure to risk, makes you take more risks later in life, or so the explanation goes. Baboons, however, don’t eat junk food to patch emotional scars from childhood. The findings published in Nature Communications suggest that medical care and lifestyle choices are only part of the story.

The most unfortunate baboons were found to be more isolated, for instance. Savanna baboons form large troops, composed of dozens or even hundreds of baboons, governed by a complex hierarchy that fascinates scientists. Lack of social support might thus be an important factor that puts both baboons and humans at risk later in life. The researchers say that 94 percent of baboon DNA is shared with humans, and just maybe these patterns are rooted in primate psychology.

“This suggests that human adult health effects from childhood stresses are not simply products of the modern environment, but have likely been present throughout our evolutionary history,” says George Gilchrist, program director in the National Science Foundation (NSF)’s Division of Environmental Biology, which funded the research.

No one knows for sure what’s going on, but researchers have some hunches as to what’s driving the mechanism. Stress hormones and changes in the epigenetic markers that control gene expression might be involved.

“Maybe all the early life adversity events are telling you something about the world you have to live in, and you have to adapt to that in certain ways,” Silk says, “and maybe there’s a tradeoff with longevity.”

holocaust survivors

Holocaust survivors encode trauma in their genes and pass it on to offspring

It seems environmental cues like smoking, fat intake, even trauma cause alterations to gene activity and expression, all while keeping the DNA sequence intact. Epigenetics is the study of such genetic alterations caused by physiological and psychological environmental exposure and the big question in the field right now is whether these genetic modifications are passed down from one generation to the next. One recent study seems to suggest that epigenetic modifications are indeed inheritable.

Holocaust survivors, for instance, passed down genetic changes associated with stress disorder (the modification was there initially for obvious reasons) to their children. These alterations were not witnessed in the control group and mark the first evidence “of transmission of pre-conception stress effects resulting in epigenetic changes in both the exposed parents and their offspring in humans,” said Rachel Yehuda, the led researcher.

holocaust survivors

Image: Euro Jew Cong

Yehuda and colleagues sequenced the genomes of  32 Jewish men and women who had either been interned in a Nazi concentration camp, were exposed to torture or persecuted (sometimes all situations applied) during the WWII. The researchers then looked at the genes of the children of the Holocaust survivors, specifically those known to cause stress disorders. Finally, the results were compared with the genes of Jews and their families who lived in the same period, but outside of persecution zones.

“The gene changes in the children could only be attributed to Holocaust exposure in the parents,” said Yehuda.

The most famous illustration of epigenetics is the unfortunate Dutch Hunger Winter, which lasted from the start of November 1944 to the late spring of 1945. During this time, West Holland was still under German control. A German blockade resulted in a catastrophic drop in the availability of food to the Dutch population. At one point the population was try­ing to survive on only about 30 percent of the normal daily calorie intake. They ate anything they could get their hands on; grass, tulip bulbs, book covers. By the time Holland was liberated in May 1945, some 20,000 people had died of starvation. Epidemiologists have been able to follow the long-term effects of the famine, but what they found completely blew their minds.

Mothers well fed around the time of conception, but malnourished only for the last few months of pregnancy gave birth to babies to smaller babies, on average. On the other hand, mothers who were malnourished for the first three months of pregnancy, but where then well fed (the blockade was lifted) were likely to birth normal-size babies. The fetus “caught up” in body weigh, sort of speak. That’s pretty straightforward so far, but in the course of the decades doctors have been following the babies they found those  who were born small stayed small all their lives, with lower obesity rates than the general popula­tion, despite having access to as much food as they wanted. That’s not all. The children of the mothers who had been malnourished only early in their pregnancies had higher obesity rates than normal. Then, some of the same effects were observed, to a lesser degree, in the children of those who had been born in those troubled time, that is to say, the grandchildren of the malnourished mothers.

But passing down epigenetic changes to offspring is still a controversial idea. It’s an established fact of science that only genes from DNA get passed on, since the genetic information in sperm and eggs shouldn’t be affected by the environmental cues that cause chemical changes in the working genes. Once fertilization occurs, any epigenetic change is thought to be wiped clear. More and more evidence seems to point otherwise. For instance, a study investigated the mechanism that transfers starvation response to future generations – as in the case of the Dutch Hunger Winter – by looking at worms. The researchers discovered that the starvation-responsive small RNAs target genes that are involved in nutrition and that these became inherited by at least three subsequent generations of worm specimens.

Sperm RNA carries marks of trauma

Scientists have shown that trauma can leave epigenetic marks – chemical changes that affect how DNA is expressed without altering its sequence. Basically, your traumatic experiences genetically affect your offspring.


Scientists have recently focused on the long term after effects of trauma, finding them to be numerous and diverse. The offspring of traumatized people are at a high risk of depression and anxiety, may have higher suicide rates – but this is difficult to explain genetically; one could argue that the traumatized parent is indirectly responsible for this, through his/her behavior, which is in turn influenced by the trauma. Now, researchers found that stress in early life alters the production of small RNAs, called microRNAs, in the sperm of mice. The mice show depressive behavior for a long time, and so do their offspring.

The study is notable for showing that sperm can be influenced by the father’s mental state, says Stephen Krawetz, a geneticist at Wayne State University School of Medicine in Detroit, Michigan, who studies microRNAs in human sperm and was not involved with this study.

“Dad is having a much larger role in the whole process, rather than just delivering his genome and being done with it,” he says. He adds that this is one of a growing number of studies to show that subtle changes in sperm microRNAs “set the stage for a huge plethora of other effects”.

Isabelle Mansuy, a neuroscientist at the University of Zurich, Switzerland, and her colleagues periodically separated mother mice from their young pups and exposed the mothers to stressful situations. They subjected the mice to this torturous experience every day, but at erratic times, so that the mothers couldn’t comfort their children in advance – morally, I find this disturbing, but from a strictly scientific point of view, you can’t argue with the method they used.

The males which were raised this way showed depressive behaviours and tended to underestimate risk, the study found. Their sperm also showed abnormally high expression of five microRNAs. One of these, miR-375, has been linked to stress and regulation of metabolism. When it came to the following generation, they were also more depressive than their control counterparts, even though they were never subjected to any trauma. To rule out the possibility that the effects of stress were transmitted socially, the researchers also collected RNA from the F1 males’ sperm and injected it into freshly fertilized eggs from untraumatized mice. This resulted in similar depressive behaviors which were passed onto the next generation.

While there is still much to be discovered about the biological underlying mechanisms, this is the first study to show that traumatized mammals affect their offspring directly through the sperm.

Source: Nature.

Writing about your traumas in third person eases recovery. Photo credit: culturestrike.net

Writing about your trauma in third person helps recovery

Writing about your traumas in third person eases recovery. Photo credit: culturestrike.net

Writing about your traumas in third person eases recovery. Photo credit: culturestrike.net

Writing your memoirs or simply recollecting traumatizing memories in writing has been used as tool in therapy for many years now. A new study by researchers at University of Iowa  found that switching to writing in third person eases recovery and improves health of participants.

Whether it’s a car accident, the death of someone close, surgery, illness, or even financial collapse, traumatic events can trigger a barrage of challenging emotions. Writing about trauma and the emotions it triggers in you can help you to put things into perspective and soothe some of your fears. That’s why therapists often advise keeping a journal and basically get traumatizing thoughts out of your head and onto paper. For some, this form of catharsis rends promising results.

He was writing his memories

Psychologists at University of Iowa found, however, that writing in third person leads to  greater health gains for participants who struggled with trauma-related intrusive thinking, as measured by the number of days their normal activities were restricted by any kind of illness.

So, instead of writing “I am worried by cancer will come back” or “I crashed the car on the freeway”, re-phrasing as “She was worried her cancer would come back” or “She crashed the car” would be better. The researchers’ analysis found that people suffering from high levels of intrusive thinking can yield higher benefits if they express their trauma in third-person.

“Third-person expressive writing might provide a constructive opportunity to make sense of what happened but from a safe distance that feels less immediate and threatening,” says Matthew Andersson, a graduate student in social psychology at the University of Iowa and a co-author on the study.

The results were reported in a paper published in the journal Stress and Health.