Age effects on white matter microstructure in individuals of self‐identified Indian ancestry from the UK Biobank

Abstract Background The incidence of dementia in India is 14%, and its prevalence doubles with every five‐year increase age. Given the lack ethnic diversity most brain research to date, it valuable study cohorts diverse genetic environmental backgrounds, identify predictors health disease that can be generalized other groups than commonly studied populations European ancestry. To address this gap literature, we modeled factors affect aging patterns brain’s white matter individuals Indian ancestry using advanced diffusion‐weighted MRI (dMRI). Method Cross‐sectional dMRI data from 123 (males, n=78; females, n=45) self‐reported (born India: 44%; mean age: 60.1±8.3 SD, range: 45‐80) UK Biobank were analyzed diffusion tensor imaging (DTI), distribution function (TDF), neurite orientation dispersion density (NODDI) apparent propagator (MAPMRI). Main effects age, sex, age‐by‐sex interaction investigated characterize trajectories whole‐brain averages corpus callosum (CC), parcellated JHU‐ICBM atlas, covarying for years education, waist/hip ratio, population structure (Figure 1) Townsend index. Normative lifespan charts created visualize major diffusivity metrics. Result centile curves (Figures 2‐3) show, increasing declining integrity, increased diffusivity, lower restriction at level CC (Table 1; Figure 4). There was no detectable effect nor interaction, across In CC, a steeper trajectory, evidenced by more pronounced changes, observed males relative females 5). Conclusion Using modeling, report diffuse changes respect age subsample Future studies should include larger sample sizes, comparisons residing India, consider vascular factors, examine genotype interactions (e.g., apolipoprotein E genotype), further risk better understand varied backgrounds.