Cardiovascular risk factors, like obesity, have already been linked to an increased risk of developing dementia. Obesity may contribute through hormonal imbalances and inflammatory processes.

For instance, leptin, a hormone involved in neuroprotection, is affected by obesity. Similarly, sex hormones like estrogen and testosterone, which play protective roles in brain health, decline with age and may further influence cognitive function.

Moreover, the APOE genotype could modulate the impact of cardiovascular risks on neurodegeneration.

A recent large-scale study examined how obesity and cardiovascular risk factors affect brain health in men and women across different age groups.

The Study
Researchers analyzed brain scans from over 34,000 participants aged 45 to 82, using advanced imaging techniques to measure changes in brain volume. They were particularly interested in in mesruring grey matter, which is crucial for cognitive function and is where the majority of the brain cells are (as comparedc to the white matter which is the connections between the barin cells and their isolation, fat).

They then analyzed the cardiovascular risks and obesity in the participants, specifically abdominal fat. The study also looked at how these factors might differ based on the participants’ genetic makeup, particularly the presence of the apolipoprotein E (APOE) ε4 gene, which is linked to Alzheimer's disease.

The findings revealed that cardiovascular risk and obesity had the most significant impact on brain volume, that is, it made the brain shrink. The impact was most pronounced in men between the ages of 55 and 64 and in their temporal lobes. For women, the greatest effects were seen a decade later, between ages 65 and 74.

These associations between heart health, obesity, and reduced brain volume were consistent in both men and women, even when the participants were divided by whether or not they carried the APOE ε4 gene. This suggests that cardiovascular and obesity-related factors can harm brain structure regardless of genetic predisposition, though the timing and degree of impact differ between the sexes.

The study underscores the importance of targeting cardiovascular risks and obesity at different times in life for men and women to reduce the risk of neurodegeneration and Alzheimer’s disease.

For men, focusing on heart health and weight control in midlife (55-64 years) may be critical, while for women, similar interventions should be prioritized a decade later, around 65-74 years. These insights could help shape future public health strategies to prevent brain aging and cognitive decline.

About the scientific paper:

First author: Joseph Nowell, UK
Published in: Journal of Neurology, Neurosurgery and Psychiatry. November 2024. 
Link to paper: https://jnnp.bmj.com/content/early/2024/11/07/jnnp-2024-333675.long