Age-related difference in gray matter volumes is heterogeneous across cerebellar regions but neither related to the topological organization nor the associated sensorimotor function

Abstract

Aging affects cerebellar structure, yet the regional specificity of this decline and its relationship to sensorimotor functions remain unclear. In this study, we quantified age-related cerebellar gray matter differences in 50 young and 80 older adults using both anatomically defined cerebellar parcellations and a functionally defined cerebellar atlas. Across both anatomical and functional parcellations, older adults showed robust reductions in gray matter volume relative to young adults. This age-related gray matter vulnerability was region-specific as age differences varied significantly across regions: both the current dataset and the additionally used Cam-CAN dataset demonstrated a larger negative effect of age in the posterior than the anterior lobe, and a smaller difference in the action domains than in the other functional domains . Structural covariance analyses revealed that correlations between cerebellar regions were determined primarily by spatial proximity and, to a lesser extent, by medial-ateral (vermis-hemisphere) organization or functional similarity. Importantly, the topological organization of the cerebellum did not differ across age groups, indicating preserved structural patterns despite widespread gray matter loss. Finally, despite substantial interindividual variability in behavioral, regional cerebellar gray matter volumes, whether anatomically or functionally defined, did not predict inter-individual variability for any of our eight cerebellum-dependent outcomes. This absence of structure-function relationship suggests that behavioral performance is maintained through compensatory mechanisms or microstructural features not captured by regional gray matter volume. Together, the results suggest heterogeneous age-related cerebellar degeneration alongside preserved topological organization and no measurable impact on cerebellar sensorimotor function, supporting the notion of a robust cerebellar reserve throughout healthy aging.