A study published in JAMA Network Open has found that individuals who eat a healthy diet and have a low waist-to-hip ratio (WHR) in midlife tend to have better brain and cognitive health in old age.
Since the early 1970s, body mass index (BMI)—which estimates body fat using height and weight—has been widely used as a health assessment indicator.
BMI is commonly used as a screening tool to evaluate the risk of cardiovascular diseases, type 2 diabetes, non-alcoholic fatty liver disease, and cancer. However, previous studies have highlighted limitations in using BMI to predict body fat and overall health, leading researchers to explore whether WHR could be a better alternative.
Earlier research suggested that WHR may be more effective than BMI in weight management and that a higher WHR is associated with a greater risk of cognitive impairment. Expanding on this, a recent study found that individuals who maintain a low WHR and a healthy diet in midlife exhibit better brain and mental health in old age.
The research team analyzed data from the Whitehall II Study, which measured participants’ dietary habits and WHR three times over 30 years, and data from the Whitehall II Imaging Substudy, which performed brain MRI scans and cognitive assessments on some participants.
At the start of the Whitehall II Study, the average age of participants was 48, and the study followed them until they reached an average age of 70.
The researchers explained that midlife is a critical period for preventive interventions to maintain cognitive health and reduce dementia risk. Therefore, the study specifically focused on midlife diet and WHR over the research period.
Their goal was to examine the long-term effects of diet quality and WHR on brain network connectivity and cognitive function, addressing inconsistencies among previous studies.
The findings suggest that a high-quality diet and a low WHR in midlife are linked to better structural and functional connectivity in the hippocampus in old age. This supports the idea that modifiable lifestyle factors, such as diet and WHR management, are essential in enhancing brain connectivity, particularly in the hippocampus.
The hippocampus is a key region responsible for memory and learning. The research team suggested that interventions targeting dietary improvements and central obesity (abdominal fat) in midlife may be the most effective in reducing future cognitive decline and dementia risk.
They also found that lower WHR in midlife was associated with better working memory and executive function in old age.
Since there is a clear link between low WHR in midlife and improved cognitive function in old age, researchers have emphasized the importance of managing central obesity to maintain mental health.
In other words, reducing abdominal fat through lifestyle interventions could help preserve cognitive abilities essential for daily living and decision-making in old age.
The study noted that the relationship between WHR in midlife and cognitive performance in old age is mediated by white matter connectivity, suggesting that metabolic health in midlife influences brain structure and cognitive function.
As the global population ages, the prevalence of cognitive decline and dementia is expected to rise, making it increasingly urgent to develop effective treatments to improve the quality of life for high-risk individuals and patients.
Experts stress that understanding how lifestyle factors affect brain health can help develop preventive strategies to reduce cognitive decline risks while also alleviating the financial burden of dementia-related healthcare costs.
Furthermore, they recommend consulting a registered dietitian nutritionist (RDN) to receive personalized nutritional guidance and identify specific neuroprotective strategies tailored to individual needs.
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