Midlife Diet and Body Fat Affect Brain Health in Older Age

TOPLINE:

Improved diet quality and reduced waist-to-hip ratio (WHR) during midlife were linked to improved brain and cognitive health in older age, indicating that efforts to enhance diet and address central obesity may be most beneficial between the ages of 48 and 70 years.

METHODOLOGY:

• Researchers analysed data from the Whitehall II study, which tracked British civil servants for over 30 years through 13 study waves, to explore how changes in diet quality and WHR during midlife relate to brain connectivity and cognitive performance in older age.
• They included 512 participants (mean age, 47.8 years at wave 3; 21.3% women) for diet quality assessment and 664 participants (mean age, 47.7 years at wave 3; 19.9% women) for WHR analysis.
• Diet quality was assessed using the Alternative Healthy Eating Index–2010 score and was measured three times (waves 3, 5, and 7) over 11 years in participants aged 48-60 years. In contrast, WHR was measured five times (waves 3, 5, 7, 9, and 11) over 21 years in participants aged 48-68 years.
• Structural and functional connectivity of the hippocampus were assessed using diffusion tensor imaging and resting state functional MRI, respectively.
• Cognitive performance was evaluated through tests of working memory, fluency, and executive function, with overall cognitive health assessed using the Montreal Cognitive Assessment.

TAKEAWAY:

• Improved diet quality in midlife was associated with increased functional connectivity between the left hippocampus and the occipital lobe and cerebellum (total volume, 9176 mm³; P < .05), as well as a small cluster between the right hippocampus and cerebellum (total volume, 136 mm³; P = .04).
• Individual improvements in diet quality over 11 years were associated with increased white matter integrity, indicated by increased fractional anisotropy (19,432 mm³; P < .05) and reduced mean diffusivity (5560 mm³; P < .05) and axial diffusivity (2600 mm³; P < .045).
• Elevated WHR in midlife was associated with increased mean diffusivity and radial diffusivity, affecting 26.4% and 23.1% of total white matter tracts, respectively. It was also associated with reduced fractional anisotropy in 4.9% of the white matter skeleton.
• The association between midlife WHR and cognitive performance was partially mediated by white matter connectivity, with global fractional anisotropy mediating 15% of the effect on digit span performance.

IN PRACTICE:

“These findings suggest that interventions to improve diet and manage central obesity might be best targeted in midlife (ages 48-70 years) to obtain beneficial outcomes for brain and cognitive health in older age,” the authors wrote.

“This study highlighted the relevance of improving the food environment for better brain structure and function in later life,” an expert wrote in an accompanying editorial.

SOURCE:

The study was led by Daria E. A. Jensen, DPhil, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, and was published online on March 12, 2025, in JAMA Network Open.

LIMITATIONS:

The cohort consisted predominantly of White British individuals with high educational attainment and was susceptible to survival bias, making it generally healthier that the broader UK population and potentially limiting the generalisability of the findings to more diverse populations. The cohort consisted predominantly of men, limiting the statistical power to analyse sex differences, particularly given evidence of sex differences in WHR and associated cognitive outcomes. Diet quality was assessed using the Alternative Healthy Eating Index, which may not be suitable for all populations.

DISCLOSURES:

This study was supported by grants from the National Institute for Health and Care Research Oxford Health Biomedical Research Centre and the Wellcome Centre for Integrative Neuroimaging. Some authors reported receiving grants from the Wills Trust, the Wellcome Trust/National Institute for Health and Care Research, the Oxford Biomedical Research Centre, or other organisations.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.