A new study has found that diet quality and waist-to-hip ratio in midlife are linked to brain connectivity and cognitive performance in older age.
Researchers from Oxford University, University College London, and institutions across Germany, France, and the Netherlands analyzed data from the Whitehall II Study, a long-term research project following British civil service workers.
Their findings suggest that a healthier diet and a lower waist-to-hip ratio during midlife are associated with better brain health in later years.
With global dietary shifts leading to rising obesity rates, cardiovascular disease and type 2 diabetes, the risk of dementia is also increasing.
While much research has focused on the effects of individual nutrients on brain function, fewer studies have assessed the long-term impact of overall diet quality and fat distribution.
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This study, published in JAMA Network Open, highlights midlife as a crucial period for cognitive health interventions.
Researchers examined the association between diet, waist-to-hip ratio, and brain connectivity, providing new insights into how these factors influence memory and executive function as we age.
The study involved data from 512 participants in the diet quality analysis and 664 participants in the waist-to-hip ratio analysis. Researchers measured diet quality using the Alternative Healthy Eating Index–2010 (AHEI-2010) and assessed waist-to-hip ratio at five time points over a 21-year period.
Brain structure and function were examined using diffusion tensor imaging (DTI) and functional MRI scans, while cognitive performance was tested through working memory, executive function, and fluency assessments.
Key findings include:
- Higher diet quality scores in midlife were linked to increased hippocampal connectivity to brain regions involved in memory and processing, such as the occipital lobe and cerebellum.
- Healthier diets were associated with better white matter integrity, meaning stronger brain connections that support cognitive function.
- Higher waist-to-hip ratio in midlife correlated with reduced white matter integrity, particularly in brain regions critical for memory and executive function.
- Cognitive decline linked to higher waist-to-hip ratio was partially explained by changes in brain connectivity.
These findings suggest that maintaining a healthy diet and a lower waist-to-hip ratio in midlife could protect brain function later in life. In an accompanying commentary, Dr. Sharmili Edwin Thanarajah from Goethe University Frankfurt highlighted the public health challenges posed by obesity and poor diet.
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She emphasized the need for systemic interventions rather than relying solely on personal responsibility, given that food environments often promote high-calorie, nutrient-poor diets.
The study also identified gaps in research, particularly regarding sex differences.
With only 20% of participants being female, it remains unclear whether these findings apply equally to women. Additionally, alcohol consumption was associated with poorer diet quality, though its independent effects on brain aging require further exploration.
These findings reinforce the importance of a balanced diet and maintaining a healthy weight not just for metabolic health, but for long-term cognitive wellbeing.
For those looking to protect their brain health, focusing on a nutrient-rich diet and managing body fat distribution could be key strategies in reducing dementia risk later in life.
