Mediterranean diet and longitudinal change of white matter hyperintensity in cognitively intact young and older adults

Abstract Background A healthy dietary pattern, Mediterranean diet (MeDi), has been reported to be associated with better brain and cognition. White matter hyperintensities (WMHs), seen in brain magnetic resonance imaging, are considered to be due to cerebral small vessel diseases and have been shown to predict faster cognitive decline in older adults. However, current evidence on the association between MeDi and WMH is inconsistent and longitudinal data are scarce. This study aims to examine whether better adherence to MeDi is associated with less accumulation of WMH over time. Method This longitudinal study was conducted among 183 cognitively intact adults aged 20‐80 years. MeDi was calculated from dietary data assessed by a self‐reported food frequency questionnaire, ranging from 0‐55, with a higher score indicating better adherence. WMH was assessed by 3T MRI, and log‐transformed prior to analyses. A one‐sample T‐test was used to examine if WMH burden increased from baseline to follow‐up over an average of five years. Multivariable linear regression was used to estimate the effect of MeDi on the change in WMH. Covariates included age, gender, race/ethnicity, education, IQ, follow‐up interval, caloric intake, baseline WMH, baseline total gray matter volume, and baseline mean cortical thickness. Moderation effects by age (young: <43, middle‐aged: 43‐65, and older: ≥65 years), sex, and race/ethnicity (non‐Hispanic White and other, non‐Hispanic Black, and Hispanic) were examined, followed by stratification analyses. Result Among all participants, WMH increased from baseline to follow‐up (mean difference [follow‐up‐baseline][standard error(SE)] = 0.31[0.04], p<0.001). A higher MeDi was associated with less increase of WMH (β[SE] = ‐0.014[0.006], p = 0.034), adjusting by all covariates. The association between MeDi and WMH change was moderated by age group (young group as the reference, p‐interaction[middle‐aged*MeDi] = 0.024, p‐interaction[older*MeDi] = 0.017), adjusting by follow‐up interval: the association was observed among the young group (β[SE] = ‐0.038[0.010], p<0.001), but not among the middle‐aged ((β[SE] = ‐0.002[0.013, p = 0.872]) or the older group ((β[SE] = ‐0.002[0.009], p = 0.836). No significant moderation effects by sex or race/ethnicity were found, adjusting by age and follow‐up interval. Conclusion Better adherence to MeDi was associated with reduced increase of WMH over time. Following a healthy diet, especially at an early age, may help maintain a healthy brain.