Tag Archives: Menopause

Women really are better multi-taskers, study finds

Women really are better multi-taskers than men but only up to menopause, a new study found.

Witchcraft!
Image credits d26b73 / Flickr.

A Swiss team has found that women really do multi-task better, owing to a cocktail of sex-specific hormones. Men and menopausal women performed largely similar (bad) at multitasking tests.

The team asked 83 volunteers aged between 18-80 to walk on a treadmill with no hand supports to record how each one walked. They then asked them to take to the treadmill while performing a variation of the Stroop test — which I’ll admit right now, sounds like hell. The Stroop test is widely employed to investigate cognitive processes and check for brain damage. It basically consists of names of colors written in ink of a different color. The participant has to either read the word or name the color as fast as he or she can.

At the same time, the researchers measured arm swing asymmetry in the participants by tracking their wrist movements in 3D. The Stroop test is mainly handled by the left side of the brain, as is the swinging motion of the right hand. So, by comparing the difference in their control gait to their test-gait, the team measured how well their left hemisphere handled two activities at the same time. In other words, the less able they were to move their right hand, the less ‘brain’ they had available.

“We know that the left hemisphere of the brain is responsible for both the verbal task and the control of arm swing on the opposite side of the body,” said doctoral student and first author Tim Killeen, from the University Hospital Balgrist.

Women under 60 were almost completely free from this effect. Men and menopausal women showed a marked reduction in arm-swinging proficiency, which impacted their balance. The team believes that female sex hormones act on the brain to improve its multi-tasking abilities. As the hormones level drop later in life, women may find multi-tasking as tricky as men, the study suggests.

“In men and older women, the verbal task appears to overwhelm the left brain to the extent that the movement of the arm on the right is reduced. We were surprised to find such a consistent gender difference in how two relatively simple behaviours – cognitive control and arm swing – interact with one another.”

“Others have shown that women are better at switching between tasks than men. We show that women are apparently better, i.e. less susceptible to interference during walking and talking and that this ability apparently fades after 60.”

This settles a long debate, doesn’t it? Well, not really. To me, it seems that these results make perfect sense. I’ve seen my girlfriend texting and dodging heavy traffic without breaking a sweat, while I can’t even handle dialing and talking at the same time. But some papers contravene these findings directly, and there is some evidence that brain age also plays a part in multitasking.

Further research will have to either back-up or deny these results, and determine whether or not they can be generalized to other multi-tasking tasks such as walking and texting. Until then, the debate will have to rage on.

The full paper “Increasing cognitive load attenuates right arm swing in healthy human walking” has been published in the journal Royal Society Open Science.

menopause

The link between premature menopause and a woman’s reproductive history

menopause

Credit: Pixabay.

A study which looked at the reproductive history of more than 51,000 women has found a link between premature or early menopause and an early first menstruation. The number of children birthed during their reproductive history also influenced the age of menopause. For instance, women who got their first period before age 12 and had no children were five times more likely to experience premature menopause than women who had their first period at age 12 or later, and had two or more children.

Menopause is the time in most women’s lives when menstrual periods stop permanently, and they are no longer able to bear children. When menopause occurs before the age of 40, it is referred to as premature menopause. If menopause occurs between age 40 and 44, it’s considered early menopause.

As to why menopause exists in the first place, the jury isn’t out yet but we have some interesting hints. A study on killer whales suggests menopause emerged as a genetic safeguard to the legacy of the family, reducing competition for younger females.

Premature menopause can be caused by a variety of factors, the most common cause being premature ovarian failure. Other causes include damage to the ovaries by chemotherapy and/or radiation treatments, or surgical removal of the ovaries.

Researchers from the University of Queensland, Australia, wanted to know if a woman’s reproductive history could also influence premature menopause. With this aim, they combed through nine observational studies which totaled 51,450 participants from Australia, Japan, U.K., and Scandinavia. The data was adjusted for various factors that might influence menopause age like marital status, smoking, body mass index (BMI) or year of birth.

The year of birth is particularly important to normalize among the participants. Two-thirds of the women involved in the study were born between 1930 and 1949, a time when contraceptives were far less common and when women had their first period significantly later than today.

The median age of menopause was 50 which is totally expected. Among all the participants, 2 percent experienced premature menopause and 7.6 percent experienced early menopause. However, once they dived into the data more granularly, some interesting patterns emerged. The incidence of premature and early menopause was 5.2 percent and 9.9 percent, respectively, among women who had their first period before age 12 and birthed no children, as reported in the journal Human Reproduction.

Having your first period before 12 does not necessarily put you at risk of premature menopause as the current findings imply a correlation, not causation. Furthermore, the study has its limitations. The age of first menstruation, for instance, was self-reported and there’s always the risk that some women might have incorrectly recalled the age.

Nevertheless, doctors may decide to prepare women with no children and an early first menstruation for the possibility of early menopause. This might help them make more informed decisions. For instance, a woman who is aged 35 and is at risk of experiencing menopause at age 40 might want to ‘hurry up’ if she wants to have children.

“[the study] provides an opportunity for clinicians to include women’s reproductive history alongside other lifestyle factors, such as smoking, when assessing the risk of early menopause, and enables them to focus health messages more effectively both earlier in life and for women at most risk. In addition, they could consider early strategies for preventing and detecting chronic conditions that are linked to earlier menopause, such as heart disease,” said Professor Gita Mishra, Professor of Life Course Epidemiology and Director of the Australian Longitudinal Study on Women’s Health at the University of Queensland, Australia.

“The message for everyone to take on board from this and other similar studies is to think of the timing of menopause as a biological marker of reproductive ageing, which has implications for health and the risk of chronic diseases. So if we want to improve health outcomes in the later life, we need to be thinking about the risk factors through the whole of a woman’s life from the early years and the time of their first period through to their childbearing years and menopause,” Mishra said.

 

Killer whales shed light on the mystery of menopause

To this day, menopause remains a puzzling concept but researchers may be getting closer to the truth by studying orcas – killer whales.

Killer whales also reach menopause later in their life. Image credits: Robert Pittman / NOAA.

Menopause has only been identified in a handful of species, including humans, killer whales, and chimps. Killer whales start having calves when they’re around 15 and stop when they’re 30 or 40 even though they can live up to 100 years old. Now, a team led by Darren Croft of the University of Exeter published data from a 40-year-old study which offers an intriguing clue as to why the whales stop reproducing later in life.

What they found is that there seems to be some sort of biological contrast between orca generations. When older females reproduce at the same time as their daughters, the calves of the older generation have are twice as likely to not reach the age of 15. But when older whales had calves in the absence of a reproducing daughter, their offspring did just fine. Researchers believe this happens because of competition.

“It’s not that older mothers are bad mothers, that they’re not able to raise their calves as younger mothers,” says Croft. “It’s that when they enter into this competition with their daughters, they lose out and their calves are more likely to die.”

The competition, as it so often happens in nature, is centered around food. Older females are more likely to share their food with others because they feel a stronger sense of kinship to the group, while younger females feel more detached (they haven’t yet formed such a strong social bond). In fact, older females are key to the survival of others, while young mothers focus only on their calves.

“It’s not that older mothers are bad mothers, that they’re not able to raise their calves as younger mothers,” says Croft. “It’s that when they enter into this competition with their daughters, they lose out and their calves are more likely to die.”

The idea that menopause emerges as a genetic safeguard to the legacy of the family is not new and has been proposed in the case of humans as well – but in a different form. In many human cultures (both ancient and modern), grandmothers take extra care of their grandchildren. If they would have children of their own, then they wouldn’t place such an emphasis on their grandchildren and in time, the family is better off without the grandmother’s kids – this is called the Grandmother Theory. However, these new findings somewhat contradict the Grandmother Theory and come up with a different reason for menopause.

Anthropologist Kristen Hawkes, at the University of Utah doubts that this study tells the full story. She believes killer whales are very difficult to study and they’re doing all sorts of stuff we don’t yet understand so any parallel between them and humans is forced.

“They’re doing all kinds of stuff where you can’t see it, and even to get demographic data is just so tricky, because they’re all underwater and they’re long-lived,” she says.

Whatever the truth may be, menopause remains an intriguing mechanism — one for which biologists and anthropologists will doubtlessly argue for years to come.

Journal Reference: Darren P. Croft et al – Reproductive Conflict and the Evolution of Menopause in Killer Whales. DOI: http://dx.doi.org/10.1016/j.cub.2016.12.015

Menopause appeared by accident, evolved due to stay-at-home males

The evolution of the menopause was ‘kick-started’ by a fluke of nature, but then boosted by the tendency for sons and grandsons go on living close to home, a new study by Liverpool scientists suggests. The full paper, titled ‘Patterns of philopatry and longevity contribute to the evolution of post-reproductive lifespan in mammals’ is published in the journal Biology Letters here.

When you think about it from a biological point of view….Menopause doesn’t make that much sense, does it? All life is an embroidery of the fierce competition each living thing finds itself in in order to pass on its genes (for the most part). And yet, the females of some mammal species (including humans) spend up to one third of their lifespan unable to conceive offspring. So what’s the point in slamming the breaks early on one’s reproductive ability?

Now also available in musical form.
Image via flickr

In an effort to understand why this happens, University of Liverpool and Liverpool John Moores University researchers applied phylogenetic principles to see how the most common theories of why menopause evolved stand up to scrutiny. They used data from 26 different mammal species (including three distinct human populations) to test the effects lifespan, group size and each sex’s tendency to remain within family groups have on post-reproductive lifespan (PRLS)

This study, published in Biology Letters, used data from 26 different mammal species, including three different tribal or historical human populations, to test for the effects of lifespan, group size and male and female philopatry (the tendency to remain within a family group) on post-reproductive lifespan (PRLS).

First was the so-called “Grandmother hypotheses,” probably the most widely-believed explanation for the advent of menopause. According to it women outlive their reproductive period to help with raising their grandchildren. This way, they increase their chances to reach maturity and have children of their own — making the grandmother’s genes more likely to be passed on.

Another theory they looked into is that evolution didn’t actually make menopause happen — we did. Because menopause offers no obvious advantage to the female, some hold that it’s just a ‘mismatch’ that stems from the desynch between our long lifespans in the modern world compared to what we were likely to get in the wild.

The team determined that no one hypothesis could, by itself, adequately explain why menopause sets in. They suggest a new scenario, in which “non-adaptive origins followed by evolutionary tinkering” would bridge the two theories and finally explain menopause.

“Our results suggest that the menopause arose through a non-adaptive ‘mismatch’ between lifespan and reproductive span. Subsequently we think that in populations where males remained at home and females dispersed to reproduce, an adaptive benefit drove the extension of this post-reproductive period,” said evolutionary biologist, Dr Kevin Arbuckle, from the University of Liverpool.

“This adaptive benefit could have come from grandmothers looking after their sons and grandsons at home. As females tend to reproduce more reliably than males, this additional family support could have made it more likely that their grandsons successfully reproduced. ”

Co-author Dr Hazel Nichols, from Liverpool John Moores University, added: “Conflicting views in science can be challenging to reconcile, but our study suggests that both adaptive and non-adaptive ideas may be correct – it’s just that they apply to different parts of the evolution of this most unusual reproductive trait.”