Researchers have discovered that male brains tend to shrink faster than female brains as people age. A study analysing brain scans from 4,726 healthy individuals found "modest yet systematic sex differences" in brain tissue loss, with men experiencing more rapid decline in various brain regions.
As people age, their brains naturally shrink, with Alzheimer's patients experiencing more severe volume loss. Interestingly, the research suggests that brain volume loss may occur at a slower rate in women compared to men, which is notable given that women are twice as likely to be diagnosed with Alzheimer's.
"If women's brains declined more, that could have helped explain their higher Alzheimer's prevalence," co-author Anne Ravndal, a neuroscientist at the University of Oslo in Norway, told Nature journalist Rachel Fieldhous.
Researchers analysed over 12,000 brain scans from individuals aged 17 to 95, with at least two MRIs taken about 3 years apart. After accounting for sex-based brain size differences, the study found that men's brains showed more widespread decline in older age, affecting multiple regions of the cortex.
Women's brains showed less decline, with fewer regions affected and less change in cortical thickness over time. The study suggests there are sex differences in brain aging, but the authors emphasise that further research is needed to confirm and understand these findings.
Research on the aging brain has a significant sex bias, with few studies considering sex as a factor. As of 2019, only 5% of neuroscience and psychiatry studies examined sex influences, leading to inconsistent findings and uncertainty about whether men and women differ in brain decline.
Previous studies have yielded conflicting results, with some indicating greater brain decline in men and others in women. A new study from the University of Oslo aimed to clarify these differences. Researchers found sex-based differences in various brain measurements, including total brain volume, subcortical volume, cortical thickness, and surface area.
The study's findings on brain volume loss raise questions about its impact on cognitive function, which requires further investigation. While brain shrinkage is often associated with negative outcomes, some research suggests it can be beneficial in certain contexts. The study surprisingly found no sex differences in volume changes in the hippocampus, a region crucial for memory and learning, and closely linked to dementia.
In older age, women in the study showed a faster decline in hippocampal volume when adjusted for life expectancy. However, this might reflect women's longer lifespan rather than a difference in dementia risk. It could indicate a delay in aging rather than a specific risk factor.
Studying the impact of sex on brain aging is complex due to various genetic and environmental factors, compounded by a lack of longitudinal research. A 2023 review highlighted the serious consequences of scientific bias in brain aging studies, which disproportionately affects female health. When researchers accounted for life expectancy, some brain decline differences between men and women balanced out, stressing the need for more research on the aging female brain.
Courtesy: NDTV
Bd-pratidin English/ ANI
