Tag: sex differences

Categories : Immune System Mental HealthTags :

Autoimmune Disease Linked to Doubling in Depression, Anxiety, Bipolar Risks

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Risks higher in women than in men with the same condition
Chronic exposure to systemic inflammation may explain associations, say researchers

Photo by Sydney Sims on Unsplash

Living with an autoimmune disease is linked to a near doubling in the risk of persistent mental health issues, such as depression, generalised anxiety, and bipolar disorder, with these risks higher in women than in men, finds a large population-based UK study, published in the open access journal BMJ Mental Health.

Chronic exposure to the systemic inflammation caused by the autoimmune disease may explain the associations found, say the researchers.

A growing body of evidence suggests that inflammation is linked to mental ill health, but many of the published studies have relied on small sample sizes, limiting their statistical power, note the researchers.

In a bid to overcome this, they drew on data from 1.5 million participants in the recently established Our Future Health dataset from across the UK. Participants’ average age was 53; just over half (57%) were women; and 90% identified as White.

On recruitment to Our Future Health, participants completed a baseline questionnaire to provide personal, social, demographic, health and lifestyle information.

Health information included lifetime diagnoses–including for their biological parents–for a wide range of disorders, including autoimmune and psychiatric conditions.

Six autoimmune conditions were included in the study: rheumatoid arthritis; Graves’ syndrome (thyroid hormone disorder); inflammatory bowel disease; lupus, multiple sclerosis; and psoriasis.

The mental health conditions of interest were self-reported diagnoses of affective disorders, defined as depression, bipolar, or anxiety disorder.

In all, 37 808 participants reported autoimmune conditions and 1 525 347 didn’t. Those with autoimmune conditions were more likely to be women (74.5% vs 56.5%) and more likely to report lifetime diagnoses of affective disorders for their biological parents:  8% vs 5.5% for fathers; 15.5% vs 11% for mothers.

Chronic and pathogenic immune system activation—including the presence of markers of inflammation—is a hallmark of many autoimmune conditions. And in the absence of direct measurements of inflammatory biomarkers, an autoimmune condition was regarded as a proxy for chronic inflammation in this study.

The lifetime prevalence of any diagnosed affective disorder was significantly higher among people with an autoimmune disorder than it was among the general population: 29% vs 18%.

Similar associations in lifetime prevalence emerged for depression and anxiety: 25.5% vs just over 15% for depression; and just over 21% vs 12.5% for anxiety.

While the overall prevalence of bipolar disorder was much lower, it was still significantly higher among those with an autoimmune disorder than it was among the general population:  just under 1% compared with 0.5%.

The prevalence of current depression and anxiety was also higher among people with autoimmune conditions.

And the prevalence of affective disorders was significantly and consistently higher among women than it was among men with the same physical health conditions: 32% compared to 21% among participants with any autoimmune disorder.

The reasons for this aren’t clear, say the researchers, but “theories suggest that sex hormones, chromosomal factors, and differences in circulating antibodies may partly explain these sex differences,” they write.

“Women (but not men) with depression exhibit increased concentrations of circulating cytokines and acute phase reactants compared with non-depressed counterparts. It is therefore possible that women may experience the compounding challenges of increased occurrence of autoimmunity and stronger effects of immune responses on mental health, resulting in the substantially higher prevalence of affective disorders observed in this study,” they add.

Overall, the risk for each of the affective disorders was nearly twice as high—87-97% higher—in people with autoimmune conditions, and remained high even after adjusting for potentially influential factors, including age, household income, and parental psychiatric history.

No information was available on the time or duration of illness, making it impossible to determine whether autoimmune conditions preceded, co-occurred with, or followed, affective disorders, note the researchers.

No direct measurements of inflammation were made either, and it was therefore impossible to establish the presence, nature, timing or severity of inflammation, they add.

“Although the observational design of this study does not allow for direct inference of causal mechanisms, this analysis of a large national dataset suggests that chronic exposure to systemic inflammation may be linked to a greater risk for affective disorder,” they conclude.

“Future studies should seek to determine whether putative biological, psychological, and social factors—for example, chronic pain, fatigue, sleep or circadian disruptions and social isolation—may represent potentially modifiable mechanisms linking autoimmune conditions and affective disorders.”

And they suggest that it may be worth regularly screening people diagnosed with autoimmune disease for mental health conditions, especially women, to provide them with tailored treatment early on.

Source: BMJ

Categories : Ageing CancerTags :

Y Chromosome Loss in Immune Cells Creates Opportunity for Cancers

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Scanning electron micrograph of a T cell lymphocyte. Credit: NIH / NIAID

A study initiated by a University of Arizona Comprehensive Cancer Center physician-scientist has for the first time defined how loss of the Y chromosome in male immune cells negatively affects immune system function. The findings, published in Nature, may explain why loss of Y is associated with lower cancer survival rates.

In males, each cell in the body usually contains one X and one Y chromosome. “Loss of Y” is a common, nonhereditary genetic change in men in which an immune cell in the blood loses its Y chromosome. It is often associated with aging. Loss of Y has been linked to increased mortality from carcinomas for many years, though no one knew why.

This study is the first to identify and define the relationship between loss of Y in white blood cells, immune cells and tumours, providing insights as to why men with loss of Y have increased cancer risks and poorer outcomes.

“These findings represent a big step forward in our understanding of why men with loss of Y in their blood cells have a higher mortality from cancer. It turns out it’s because these cells make the immune system infiltrating the cancer less effective,” said Dan Theodorescu, MD, PhD, director of the Cancer Center and a professor in the College of Medicine – Tucson. 

“We hope this provides a solid lead and framework for the nascent Y chromosome field to pursue so we can collectively better understand all the possible biological implications of this finding and how to use them to develop more effective approaches in prevention, treatment resulting in higher survival rates for patients.”

The research team discovered that loss of the Y chromosome – previously identified in malignant epithelial cells by the Theodorescu lab – also occurred in nearby noncancerous tissues, including connective tissue and immune cells.

Most notably, the team found that this chromosomal loss in helper and cytotoxic T cells, which are responsible for attacking cancer cells, was associated with a reduced ability to kill those cancerous cells. The findings suggest a mechanism by which tumours may evade immune detection and suppression.

Finally, the research team found that loss of Y in epithelial cells, combined with loss of Y in T cells, resulted in more aggressive cancers and lower survival rates in patients.

“The study has potential implications for current immunotherapies, including CAR T therapy,” Theodorescu said. “Further research is clearly needed but perhaps immunotherapies using cells from a patient’s immune system could be screened for loss of Y before being used in treatment.”

Source: University of Arizona

Categories : Genetics Neurodegenerative DiseasesTags :

Common Gene Variant Doubles Dementia Risk for Men

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New research has found that men who carry a common genetic variant are twice as likely to develop dementia in their lifetime compared to women. The research, published in Neurology, used data from the ASPirin in Reducing Events in the Elderly (ASPREE) trial to investigate whether people who had variants in the haemochromatosis (HFE) gene, which is critical for regulating iron levels in the body, might be at increased risk of dementia.

Co-author Professor John Olynyk, from the Curtin Medical School, said one in three people carry one copy of the variant, known as H63D, while one in 36 carry two copies.

“Having just one copy of this gene variant does not impact someone’s health or increase their risk of dementia. However, having two copies of the variant more than doubled the risk of dementia in men, but not women,” Professor Olynyk said.

“While the genetic variant itself cannot be changed, the brain pathways which it affects – leading to the damage that causes dementia – could potentially be treated if we understood more about it.”

Professor Olynyk said further research was needed to investigate why this genetic variant increased the risk of dementia for males but not females.

“The HFE gene is routinely tested for in most Western countries including Australia when assessing people for haemochromatosis – a disorder that causes the body to absorb too much iron. Our findings suggest that perhaps this testing could be offered to men more broadly,” Professor Olynyk said.

“While the HFE gene is critical for controlling iron levels in the body, we found no direct link between iron levels in the blood and increased dementia risk in affected men.

“This points to other mechanisms at play, possibly involving the increased risk of brain injury from inflammation and cell damage in the body.”

The ASPREE trial was a double-blind, randomised, placebo-controlled trial of daily low-aspirin in 19 114 healthy older people in Australia and the USA. Primarily undertaken to evaluate the risks versus benefits of daily low-dose aspirin in this cohort, it created a treasure trove of healthy ageing data that has underpinned a wealth of research studies.

Source: Curtin University

Categories : Skeletal SystemTags :

Beyond Hormones: Researchers Define X and Y Chromosome Contributions to Height

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Photo by Monstera on Pexels

A Geisinger study provides new insight into height differences between adult men and women, demonstrating that Y chromosome genes contribute more to height than their X chromosome counterparts, independent of male sex determination. The results were published this week in the Proceedings of the National Academy of Sciences.

Typical females have two X chromosomes, while typical males have one X and one Y chromosome. The differences between the X and Y chromosomes cause hormonal differences between males and females, but these differences have been insufficient to explain the average 13cm height difference between the sexes.

“Because height shows a large and reproducible difference between sexes and is widely measured, it serves as a valuable model for investigating the genomic factors underlying sex differences,” said Matthew Oetjens, Ph.D., assistant professor in Geisinger’s Department of Developmental Medicine and one of the study leads.

The Geisinger research team sought to determine the effects of sex-related factors on human height by examining height in people with an abnormal number of X or Y chromosomes, a genetic condition known as sex chromosome aneuploidy.

The team analysed genetic and clinical data on nearly one million participants enrolled in Geisinger’s MyCode Community Health Initiative, the National Institutes of Health’s All of Us cohort and the UK Biobank. Of these participants, 1225 had a sex chromosome aneuploidy. By incorporating people with more or fewer than two sex chromosomes into a model of height, they found that exchanging an X for a Y chromosome increased height by 3.1cm, independent of other sex-related factors, including hormonal differences. This result suggests that an estimated 23% of the average difference in height between men and women is explained by increased expression of shared genes on the Y chromosome relative to the X chromosome.

“Beyond its implications for understanding human height, this study provides broader insights into how sex chromosome aneuploidy research can uncover the mechanisms behind observed sex differences in various medical conditions,” said Alexander Berry, PhD, bioinformatics scientist and study co-lead.

SHOX, a gene found on both the X and Y chromosomes, is a known contributor to human height, but because two copies are found in both men and women, it has not been considered a likely contributor to the sex difference in height. However, recent studies have shown that SHOX is partially silenced on the second X chromosome in individuals with two or more X chromosomes. The Geisinger study’s results are consistent with the hypothesis that reduced SHOX expression in females results in a net difference in height between the sexes.

Source: Geisinger Health System

Categories : GenderTags :

Males Are More Likely to Get Sick and Less Likely to Seek Care for Three Common Diseases

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A global analysis finds sex-based health disparities for hypertension, diabetes and HIV and AIDS

Photo by Towfiqu barbhuiya on Unsplash

In many countries, males are more likely than females to get sick and die from three common conditions, and less likely to get medical care, according to a new study by Angela Chang of the University of Southern Denmark, and colleagues, published May 1st in the open-access journal PLOS Medicine.

Many health policies are the same for males and females, even though there is strong evidence that sex and gender can substantially influence a person’s health outcomes. In the new study, researchers gathered global health data for people of different sexes and ages for three conditions, hypertension, diabetes, and HIV and AIDS. By comparing rates of diseases between males and females and differences in diagnosis and treatment, the researchers sought to illuminate and reduce health inequities between the sexes.

The analysis identified significant differences between the sexes at each step in the “health pathway,” which includes exposure to a risk factor, development of the condition, diagnosis, treatment and death. Males and females received different care for hypertension, diabetes and HIV and AIDS in 200, 39, and 76 countries, respectively. Males had higher rates of disease and higher rates of death compared to females, and in some countries, were less likely to seek out health care and adhere to treatment. In most countries, males were also more likely to smoke, while females were more like to be obese and engage in unsafe sex.

Overall, the study suggests that public health professionals need to develop strategies to encourage males to participate in preventive and health care services. The researchers also highlight the importance of examining health data by sex to understand health inequities and guide appropriate interventions at multiple points along the health pathway. They conclude that we need more comprehensive datasets for these and other conditions so that we can monitor for sex differences and implement equitable health care policies.

Professors Kent Buse and Sarah Hawkes, co-founders and co-CEOs of Global 50/50 say, “We have long advocated the benefits of publishing sex disaggregated data.  As our Gendered Health Pathways demonstrates, such data can reveal where the health journeys of men and women diverge be it in relation to the risk factors they are exposed to, their health care seeking behaviors or their experiences in health care systems. That is an important first step towards health equity. Most of these differences are not explained by sex (biology) alone, but by socially-constructed gender – highlighting the importance of taking a gender justice approach to reducing health inequities.  A gender analysis can help to shape systems of health for all.”

Angela Chang, senior author, adds, “The evidence is clear: sex differences persist at nearly every point along the health pathway, from higher smoking rates in men to higher obesity prevalence in women, yet interventions rarely reflect this. Without sex-disaggregated cascade data, we’re flying blind – unable to detect who is falling through the cracks in prevention, diagnosis, and care.”

Provided by PLOS

Categories : Cardiovascular Disease Mental HealthTags :

In Younger Women, Stress is Associated with an Increased Stroke Risk

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Credit: American Heart Association

Some people living with chronic stress have a higher risk of stroke, according to a study published on online in Neurology®, the medical journal of the American Academy of Neurology. The study looked at younger adults and found a correlation between stress and stroke, with no known cause, in female participants, but not male participants.

“Younger people often experience stress due to the demands and pressures associated with work, including long hours and job insecurity, as well as financial burdens,” said Nicolas Martinez-Majander, MD, PhD, of the Helsinki University Hospital in Finland.

“Previous research has shown that chronic stress can negatively affect physical and mental health. Our study found it may increase the risk of stroke in younger women.”

For the study, researchers looked at 426 people aged 18 to 49 who had an ischaemic stroke with no known cause. They were matched for age and sex with 426 people who did not have stroke. Participants completed a questionnaire about stress levels over a one-month period. Those with stroke were asked after their stroke to record stress levels in the month prior to their stroke.

Participants were asked 10 questions, such as “In the last month, how often have you felt that you were unable to control the important things in your life?” Scores for each question ranged from zero to four, with four meaning “very often.” A total score of 0 to 13 represented low stress; 14 to 26, moderate stress; and 27 to 40, high stress.

Those with stroke had an average score of 13 compared to those without stroke who had an average score of 10. People with stroke were more likely to have at least moderate stress levels. Of those with stroke, 46% had moderate or high stress levels compared to 33% of those who did not have stroke. After adjusting for factors that could affect risk of stroke such as education level, alcohol use and blood pressure, researchers found for female participants, moderate stress was associated with a 78% increased risk of stroke and high stress was associated with a 6% increased risk.

Researchers did not find a link between stress and stroke in male participants. “More research is needed to understand why women who feel stressed, but not men, may have a higher risk of stroke,” said Martinez-Majander.

“In addition, we need to further explore why the risk of stroke in women was higher for moderate stress than high stress. Knowing more about how stress plays a role could help us to create better ways to prevent these strokes.”

A limitation of the study was that people experiencing higher levels of stress may have been less likely to enrol in the study, which could have affected the results.

Source: American Academy of Neurology

Categories : GenderTags :

Researchers Discover New Strength-boosting Mechanism in Androgens

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Photo by Jonathan Borba on Unsplash

Researchers at Leipzig University’s Faculty of Medicine and Shandong University in China have discovered a new mechanism that is used by a key androgen essential for muscle and bone function. The findings could lead to the development of new drugs with fewer side effects, for use in applications such as strengthening the muscles of immobile patients. The researchers have published their findings in the prestigious journal Cell.

The most powerful of the androgens is called 5α-dihydrotestosterone (5α-DHT). Among other things, it is essential for bone and muscle function and for the development of secondary male sexual characteristics during puberty. As a driver of bone and muscle formation, 5α-DHT increases bone mineral density and promotes skeletal muscle growth to increase muscle strength. 

In this international study, the scientists were able to show that one of the adhesion G protein- coupled receptors – GPR133 – is activated by the androgenic steroid hormone 5α-DHT.

“This activation can, among other things, increase the contractile force of skeletal muscles, and our study also uses a newly developed, potent activator of this receptor to specifically trigger this effect,” says Professor Ines Liebscher, Professor of Signal Transduction at Leipzig University and co-leader of the study.

Increasing muscle strength with the chance of significantly fewer negative effects of androgens

Activation of GPR133 by the novel agonist AP503 increases muscle strength without triggering a specific negative effect that is otherwise observed when androgens are administered. For example, increased and prolonged exposure to testosterone can promote the development of prostate cancer, as evidenced by tissue changes in the prostate in mice after only two weeks of androgen administration. This side effect has not yet been observed with AP503.

In addition, the current study uses structural biology methods to elucidate the molecular basis of the interaction between the steroid hormone, the substance AP503 and GPR133. This will allow the activator to be specifically optimised and further developed into a new therapeutic agent. This could lead to the development of new muscle-strengthening drugs with a lower side-effect profile.

This publication is the result of a long-standing and successful collaboration between the Rudolf Schönheimer Institute of Biochemistry and the research group of Professor Jin-Peng Sun at Shandong University in China. The researchers are currently working on several follow-up studies to further investigate the use of AP503 in disease processes and the role of GPR133 in the organism. Here the data were analysed in animal models. Further studies are needed to investigate the applicability of the findings to humans.

Source: Universität Leipzig

Categories : NeurologyTags :

Sex Differences are Also Seen in Brain Immune Cells

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Image of an astrocyte, a subtype of glial cells. Glial cells are the most common cell in the brain. Credit: Pasca Lab, Stanford University
NIH support from: NINDS, NIMH, NIGMS, NCATS

New research from the University of Rochester finds that microglia function may not be as similar across sex as once thought. This discovery could have broad implications for how diseases like Alzheimer’s and Parkinson’s are approached and studied, and points to the necessity of having gender-specific research. It is already known that more women are diagnosed with Alzheimer’s and more men are diagnosed with Parkinson’s, but it’s unclear why.

Microglia are the immune cells of the central nervous system, clearing toxins in the brain. But if they are overactive, they can damage neurons instead and, in some cases, have been found to promote the progression of neurodegenerative diseases like Alzheimer’s and Parkinson’s. Although there are known sex-related differences in how microglia function, it was thought to be less variation in how they behave in adulthood. The new study showied how microglia respond differently in adult male versus female mice when given an enzyme inhibitor to block its microglia survival receptor.

“It is a fortuitous finding that has repercussions for what people are doing in the field, but also helps us understand microglia biology in a way that people may not have been expecting,” said Ania Majewska, PhD, professor of Neuroscience and senior author of the study in Cell Reports. “This research has a lot of ramifications for microglia biology and as a result all these diseases where microglia are important in a sex-specific manner.”

Pexidartinib or PLX3397 is an enzyme inhibitor commonly used to remove microglia in the lab setting to help researchers better understand the role of these cells in brain health, function, and disease. PLX3397 is also used to treat the rare disease tenosynovial giant cells tumours (TGCT), a condition that causes benign tumours to grow rapidly in the joints.

Researchers in the Majewska Lab were using PLX3397 in male versus female experiments but continued to run into difficulties, so they decided to take a different approach with the inhibitor. Instead of using it to ask other questions, they decided to better understand how microglia were responding to the drug in males versus females.

First author Linh Le, PhD (‘24), currently a Research Scientist, SetPoint Medical Corp, was a graduate student in the Majewska Lab when she found the expected response from microglia to PLX3397 in male mice: it blocked the receptor that signals microglial survival and depleted the microglia. However, Le, et al, were surprised to find that female microglia responded with a different signalling strategy that resulted in increased microglial survival and less depletion.

“These findings are crucial in the rapidly emerging field of developing disease-modifying therapies that target microglia,” said Majewska. “We do not yet know why the microglia are acting differently in the two sexes. I think we’d like to understand how the signaling through this receptor is regulated in different conditions, such as hormonal changes, basal state, inflammatory, or an anti-inflammatory state.”

Source: University of Rochester Medical Center

Categories : Injury & Trauma NeurologyTags :

Men More Than Three Times as Likely to Die From a Brain Injury, New Study Shows

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Photo by Anna Shvets

A new analysis of mortality data reveals the disproportionate impact of traumatic brain injuries (TBI) on older adults, males and certain racial and ethnic groups. The study, published in the peer-reviewed journal Brain Injury, provides a comprehensive analysis of TBI-related deaths across different population groups across the US in 2021.

The findings indicate that suicides remain the most common cause of TBI-related deaths, followed by unintentional falls, and specific groups are disproportionately affected by these tragedies.

Men, in particular, were found to be most likely to die from a TBI – more than three times the rate of women (30.5 versus 9.4). The reasons observed were multifactorial and could reflect differences in injury severity following a fall or motor vehicle crash, to the interaction of sex and age – with TBI outcomes in men worsening with age, while postmenopausal women fare better than men of similar age.

“While anyone is at risk for getting a TBI, some groups have a higher chance than others of dying from one. We identified specific populations who are most affected. In addition to men, older adults are especially at risk, with unintentional falls being a major cause of TBI-related death. American Indian or Alaska Native people also have higher rates of these fatal injuries,” says lead author Alexis Peterson PhD, of the National Center for Injury Prevention and Control at the Centers for Disease Control and Prevention.

“These findings highlight the importance of tailored prevention strategies to reach groups who may be at higher risk and the role healthcare providers can play in reducing TBI-related deaths through early intervention and culturally sensitive care.”

TBI remains a leading cause of injury-related death in the US In 2020, TBIs were associated with around a quarter of all injury-related deaths.

Using data from the National Vital Statistics System, the new analysis identified 69 473 TBI-related deaths among US residents during 2021. The age-adjusted TBI-related mortality rate was 19.5 per 100 000, representing an 8.8% increase from 2020.

Through statistical modeling, the researchers examined the simultaneous effect of multiple factors such as geographic region, sex, race and ethnicity, and age, on TBI-related mortality.

Key findings include:

  • Older adults (75+) had the highest rates of TBI-related deaths, with unintentional falls being the most common cause in this age group.
  • Non-Hispanic American Indian/Alaska Native individuals experienced the highest TBI-related death rate (31.5) compared to other racial and ethnic groups.
  • There were 37,635 TBI-related deaths categorised as unintentional injuries (ie, motor vehicle crashes, unintentional falls, unintentionally struck by or against an object, other).
  • 30,801 were categorized as intentional injuries (ie, all mechanisms of suicide and homicide).
  • Children aged from birth to 17 years accounted for around 4% of TBI-related deaths (2,977).

The authors emphasise the critical role of healthcare providers in preventing TBI-related deaths, particularly with groups at higher risk. “By assessing patients who may be at higher risk for TBI, especially due to falls or mental health challenges, healthcare providers can make timely referrals and recommend culturally tailored interventions to prevent further injury or death,” says Dr Peterson.

Public health efforts should focus on addressing the underlying causes of TBI-related deaths, such as unintentional falls and mental health crises, to help prevent further loss of life. “TBIs remain a significant public health concern, especially among older adults, men, and certain racial and ethnic groups,” says Peterson.  “CDC has proven resources that healthcare providers can use to not only reduce health disparities that increase the risk for TBI but also improve care for anyone affected by a TBI.”

The authors note the COVID-19 pandemic could have influenced TBI-related death trends in 2021. They also acknowledge several limitations of this analysis, including potential misclassification or incomplete documentation of causes on death certificates, which may lead to inaccuracies in estimating TBI-related deaths.

Source: Taylor & Francis Group

Categories : Gender NeurologyTags :

Sex Differences in Brain Structure Present at Birth

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Photo by Chayene Rafaela on Unsplash

Sex differences in brain structure are present from birth, research from the Autism Research Centre at the University of Cambridge has shown.

While male brains tended to be greater in volume than female brains, when adjusted for total brain volume, female infants on average had significantly more grey matter, while male infants on average had significantly more white matter in their brains.

Grey matter is made up of neuron cell bodies and dendrites and is responsible for processing and interpreting information, such as sensation, perception, learning, speech, and cognition.  White matter is made up of axons, which are long nerve fibres that connect neurons together from different parts of the brain. 

Yumnah Khan, a PhD student at the Autism Research Centre, who led the study, said: “Our study settles an age-old question of whether male and female brains differ at birth. We know there are differences in the brains of older children and adults, but our findings show that they are already present in the earliest days of life.

“Because these sex differences are evident so soon after birth, they might in part reflect biological sex differences during prenatal brain development, which then interact with environmental experiences over time to shape further sex differences in the brain.”

One problem that has plagued past research in this area is sample size. The Cambridge team tackled this by analysing data from the Developing Human Connectome Project, where infants receive an MRI brain scan soon after birth. Having over 500 newborn babies in the study means that, statistically, the sample is ideal for detecting sex differences if they are present.

A second problem is whether any observed sex differences could be due to other factors, such as differences in body size.  The Cambridge team found that, on average, male infants had significantly larger brain volumes than did females, and this was true even after sex differences in birth weight were taken into account.

After taking this difference in total brain volume into account, at a regional level, females on average showed larger volumes in grey matter areas related to memory and emotional regulation, while males on average had larger volumes in grey matter areas involved in sensory processing and motor control.

The findings of the study, the largest to date to investigate this question, are published in the journal Biology of Sex Differences.

Dr Alex Tsompanidis who supervised the study, said: “This is the largest such study to date, and we took additional factors into account, such as birth weight, to ensure that these differences are specific to the brain and not due to general size differences between the sexes.

“To understand why males and females show differences in their relative grey and white matter volume, we are now studying the conditions of the prenatal environment, using population birth records, as well as in vitro cellular models of the developing brain. This will help us compare the progression of male and female pregnancies and determine if specific biological factors, such as hormones or the placenta, contribute to the differences we see in the brain.”

The researchers stress that the differences between males and females are average differences.

Dr Carrie Allison, Deputy Director of the Autism Research Centre, said: “The differences we see do not apply to all males or all females, but are only seen when you compare groups of males and females together. There is a lot a variation within, and a lot of overlap between, each group.”  

Professor Simon Baron-Cohen, Director of the Autism Research Centre, added: “These differences do not imply the brains of males and females are better or worse. It’s just one example of neurodiversity. This research may be helpful in understanding other kinds of neurodiversity, such as the brain in children who are later diagnosed as autistic, since this is diagnosed more often in males.”

The research was funded by Cambridge University Development and Research, Trinity College, Cambridge, the Cambridge Trust, and the Simons Foundation Autism Research Initiative.

Reference
Khan, Y.T., Tsompanidis, A., Radecki, M.A. et al. Sex differences in human brain structure at birth. Biol Sex Differ; 17 Oct 2024; DOI: 10.1186/s13293-024-00657-5

Republished under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Source: University of Cambridge