The associations of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet with brain structural changes are unclear. Among 26,466 UK Biobank participants, a 15-point MIND score was calculated from 24-hour diet recalls from2009 to 2012. We assessed its associations with 17 magnetic-resonance-derived brain volumetric markers and their longitudinal changes and explored whether genetic factors modify the associations. Higher MIND adherence was associated with larger volumes of thalamus, putamen, pallidum, hippocampus, and accumbens (beta per 3-unit increment ranging from 0.024 to 0.033) and lower white matter hyperintensities (P-trends<0.05), regardless of genetic predispositions of Alzheimer's disease. MIND score was not associated with their longitudinal changes (P>0.05) over a median of 2.2 years among participants with repeated imaging assessments (N = 2963), but was associated with slower atrophy in putamen (beta: 0.026, P-trend=0.044) and pallidum (beta: 0.030, P-trend=0.033) among APOEε4 non-carriers (N = 654). The MIND diet showed beneficial associations with certain brain imaging markers, and its associations with long-term brain structural changes warrants future investigation. Adherence to the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet was significantly associated with higher volumes and larger gray matter volumes in certain brain regions in UK adults, and the associations were not modified by genetic factors. No significant associations were observed between MIND diet and longitudinal changes in the investigated brain structural markers over a median of 2.2 years. Higher MIND score was significantly associated with slower atrophy in the putamen and pallidum among APOEε4 non-carriers.