Sex differences in brain gene activity could explain why some disorders affect men and women differently

The physical differences between men and women are all too obvious, but the biological divide goes right down to the cellular level in the brain, according to a new study published in the journal Science.

While we have known for a long time that men and women face different risks for brain disorders such as depression and Alzheimer's, we haven't always known why.

Most previous research has focused on broad sections of brain tissue, but in this study, a team of researchers analyzed more than one million nuclei from six different cortical regions from 30 donors.

Previous MRI scans of these brain regions had shown physical differences in size or volume between the sexes. The scientists wanted to see if gene activity matched the physical differences seen on the scans.

The technique they used was single-nucleus RNA sequencing, which allows researchers to examine the genetic instructions within individual cells. Specifically, the focus was on how gene expression varies across different cell types and regions.

The study identified more than 3,000 genes that differ in expression between males and females. These differences included how genes are turned on or off and how active genes are in producing RNA messages that guide protein production. What's more, they aren't spread evenly across the brain, as the team explains, "Broader effects of sex on autosomal expression are captured in 13 core signatures with varying cell type versus region specificity."

For example, the differences were much stronger (a higher number of genes were behaving differently) in certain areas like the fusiform cortex, which is a part of the brain involved in face recognition and complex visual processing.

Some of the strongest variations were seen in glial cells, which insulate neurons, but perhaps not surprisingly, the biggest differences were in the sex chromosome genes (X and Y). However, hundreds of genes across the entire genome are also influenced by sex.

When it comes to disease risk, the study found that some of the genes showing sex differences are the same ones linked to brain conditions that affect men and women differently, such as autism, ADHD, Alzheimer's disease and mood disorders.

Alex R. DeCasien et al, Sex effects on gene expression across the human cerebral cortex at cell type resolution, Science (2026). DOI: 10.1126/science.aea9063

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original article

Daytime napping patterns may reveal hidden health decline in older adults

New research reveals that as people age, naps may be an easily trackable warning sign of underlying conditions or declining health. 

A new study by investigators  followed 1,338 older adults for up to 19 years to track napping habits and associated mortality rates. They found longer, more frequent, and morning naps were associated with higher mortality rates.

Excessive napping later in life has been linked to neurodegeneration, cardiovascular diseases and even greater morbidity.

Between 20 and 60% of older adults take naps. While infrequent napping can be restorative, excessive daytime napping in old age has been linked to a wide range of health issues.

19 years' worth of data were collected from 1,338 total participants. The researchers analyzed the data for associations between napping patterns at the initial assessment and all-cause mortality during the 19-year follow-up, finding that longer, more frequent, and 'morning naps' were all associated with higher mortality.
Each additional hour of daytime napping per day was associated with around 13% higher mortality risk; each extra nap per day was associated with around 7% higher mortality risk; and morning nappers had 30% higher mortality risk compared to afternoon nappers. Irregular napping patterns were not associated with any increased mortality risk.

It is important to note that this is correlation not causation. Excessive napping is likely indicating underlying disease, chronic conditions, sleep disturbances, or circadian dysregulation

Now that we know there is a strong correlation between napping patterns and mortality rates, we can make the case to implement wearable daytime nap assessments to predict health conditions and prevent further decline.

Objectively Measured Daytime Napping and All-cause Mortality in Older Adults, JAMA Network Open (2026). DOI: 10.1001/jamanetworkopen.2026.7938