Biological Age Prediction of the Cerebellar Vermis in the Human Lifespan

The cerebellar vermis undergoes diverse structural changes with aging, yet region-specific aging patterns remain underexplored. Using Brain Structure Age (BSA), a deep learning biomarker from structural magnetic resonance imaging (MRI), we aimed to: (1) evaluate effects of volume, BMI, and education on vermis aging; (2) examine sex differences; and (3) analyze aging trajectories across young (20-39), middle-aged (40-59), and older adults (≥ 60). A cross-sectional study of 245 healthy participants from the Iranian Brain Imaging Database utilized high-resolution 3D T1-weighted images from a 3T MRI with a 64-channel coil. We calculated BSA and cerebellar vermis subregional volumes (lobules I-V, VI-VII, VIII-X). ANCOVA models examined the impact of age group, sex, BMI, education, and vermis volume on biological age, with Bonferroni-adjusted post hoc comparisons. The results revealed robust age-dependent gradients, with posterior lobules VIII-X showing the steepest decline (adjusted R² = 0.747-0.784, p < 0.001). Volumetric preservation was protective in the anterior and posterior superior subregions (lobules I-V: β = - 1.75, p = 0.003; VI-VII: β = - 3.78, p = 0.004, respectively), but not in VIII-X (p = 0.861). A marginal age group × sex interaction suggested accelerated male aging in older groups. BMI and education had no significant effects (p > 0.15). Models explained 74.7-79.1% of variance in biological age (R² = 0.747-0.791). In conclusion, BSA identifies distinct aging patterns in the cerebellar vermis, with posterior subregions being more vulnerable, highlighting anterior-posterior gradients and minimal lifestyle influence.