Men's brains drain faster with age than women's, new research suggests

New research shows men's brains shrink faster structurally with age, but scientists say this does not explain why women account for most Alzheimer's cases, pointing to deeper biological factors

An international study has found that men’s brains appear to shrink faster than women’s as they age, raising fresh questions about differences in brain health and dementia risk.

 

The research, published in the journal Proceedings of the National Academy of Sciences (PNAS) under the title 'Sex differences in healthy brain aging are unlikely to explain higher Alzheimer’s disease prevalence in women', analysed thousands of MRI scans to understand how male and female brains age differently.

 

What the study found

 

Researchers examined over 12,000 MRI scans from healthy adults aged 17 to 95 to track changes in brain structure over time. Key findings include:

 

 

• Men had greater structural decline in several brain regions, including areas of the cortex and subcortex
• Women showed less overall shrinkage, although they experienced increased expansion of the fluid-filled ventricles in older age

 

These changes were observed after adjusting for differences in brain size between sexes. The researchers concluded that these “modest yet systematic sex differences” suggest that the brains of men may age more quickly at a structural level than those of women.

 

Researchers also observed no meaningful sex differences in hippocampal volume loss with age, even though the region is critical for memory and dementia risk. Once differences in life expectancy were considered, several brain-ageing disparities between men and women diminished, pointing to the need for more nuanced research on the ageing female brain.

 

Why it matters

 

Brain shrinkage, often called atrophy, is a natural part of ageing, but the pace and pattern of this shrinkage can vary widely. Understanding sex differences in this process could help scientists identify why certain age-related conditions, such as dementia and Alzheimer’s disease, affect men and women differently.

 

Interestingly, while men’s brains appear to shrink faster, women are still diagnosed with Alzheimer’s disease at far higher rates. "If women's brains declined more, that could have helped explain their higher Alzheimer's prevalence," co-author Anne Ravndal, neuroscientist at the University of Oslo in Norway, told Nature.

 

Researchers noted that while the new findings are compelling, they should be interpreted with caution and that more research is needed to fully understand what these brain changes mean for cognition and health.

 

The Alzheimer’s paradox

 

Women account for nearly two-thirds of all Alzheimer’s cases worldwide. Despite faster structural aging in male brains, the study found that these differences did not explain why women are more likely to develop Alzheimer’s. This suggests other factors such as hormones, genetics, lifestyle or biochemical changes may play a larger role in women’s dementia risk.

 

Experts note that longer life expectancy in women only partially explains this disparity. Researchers believe deeper biological and social factors may be at play. Hormonal shifts during menopause may affect how the brain uses energy and copes with stress. Genetics also matters, with the APOE e4 risk gene shown to have a stronger impact on Alzheimer’s risk in women.

 

Limitations of the study

 

• No cause-and-effect conclusions: The MRI-based analysis shows patterns of brain ageing but cannot explain the underlying biological causes.
• Focused on healthy ageing: Participants did not have diagnosed neurological disease, limiting insights into how these changes relate to Alzheimer’s progression.
• Structure over function: The study assessed brain volume changes, not cognitive performance or memory outcomes.
• Key risk factors not measured: Hormonal status, genetic risk and lifestyle influences were not directly analysed.

   

For more health updates, follow #HealthwithBS

This report is for informational purposes only and is not a substitute for professional medical advice.