Long-term Healthy Diet Associated With Greater Hippocampal Volumes

Study data published in the American Journal of Medicine suggest an association between a long-term healthy diet and larger total hippocampus volume.

Investigators selected 550 individuals at random from the Whitehall II cohort study for participation in the Whitehall II Brain Imaging sub-study. The Whitehall II cohort study comprises 10,308 British civil servants from whom extensive clinical and demographic information is collected every 5 years. Dietary intake was assessed per a semi-quantitative food frequency questionnaire in the study waves of 1991 to 1993, 1997 to 1999, and 2003 to 2004. The Alternative Healthy Eating Index 2010 (AHEI-2010) was used to assess diet quality for individuals in the Brain Imaging sub-study. Magnetic resonance imaging (MRI) was also abstracted from the Whitehall II cohort, including details on brain tissue segmentation and hippocampal volume. Linear regression analyses were adjusted for age, sex, total energy intake, occupational grade, physical activity, smoking status, cardiometabolic disorders, cognitive impairment, and depressive symptoms.

Of the 550 original participants, 459 were included in main analyses. Individuals excluded after the initial recruitment period did not differ in any significant way from the analyzed cohort. Mean AHEI-2010 score differed across age brackets and racial/ethnic groups. Specifically, lower mean AHEI-2010 scores were observed in white participants and smokers compared with non-white participants and non-smokers, respectively. AHEI-2010 was inversely associated with body mass index (BMI) and was lower in participants with depressive symptoms. Hippocampal volumes were lower in older individuals, individuals with type 2 diabetes, and individuals with hypertension. Per linear regression models, higher AHEI-2010 scores were significantly associated with greater hippocampal volumes. In the fully adjusted model, each increase of 1 standard deviation (SD) in AHEI-2010 score was associated with an increase of 56.3 mm³ (standard error [SE], 23.0 mm³) in left hippocampal volume and 36.2 mm³ (SE, 22.7 mm³) in right hippocampal volume. Participants who improved their diet or maintained a high AHEI-2010 score had larger hippocampal volumes compared with participants who maintained a low AHEI-2010 score over the study period. In the fully adjusted model, low alcohol consumption was associated with greater total, right, and left hippocampal volumes.

This study presents strong evidence for an association between a healthy diet and hippocampal volumes. Component analyses support the hypothesis that frequent, intensive alcohol consumption may have a deleterious effect on the brain compared with low consumption. Further research is necessary to explore the mechanisms which underlie this association between diet and brain structure, including metabolic, inflammation, and vascular pathways.

Reference

Akbaraly T, Sexton C, Zsoldos E, et al. Association of long-term diet quality with hippocampal volume: longitudinal cohort study [published online July 26, 2018]. Am J Med. doi:10.1016/j.amjmed.2018.07.001