Age and Sex Differences in the Cerebellum and the Ventral Pons: A Prospective MR Study of Healthy Adults

The human brain exhibits a complex pattern of differential aging. The purpose of this study was to examine whether age differences in the volume of cerebellar regions and the ventral pons are differential or generalized, whether the age-related shrinkage is linear or exponential, and whether there are sex differences in the size of the cerebellum and pons. The volumes of the cerebellar hemispheres (excluding the vermis and the peduncles), the vermis, and the ventral pons were estimated from the prospectively acquired MR scans of 190 healthy volunteers (aged 18-81 years). The relation between regional volumes, age, and sex was assessed while taking into account differences in body size (height). We found a moderate age-related reduction in the volume of the cerebellar hemispheres and the cerebellar vermis. In contrast to previous findings that suggested differential vulnerability of the posterior vermis, the age-related shrinkage of the vermian lobules was uniform-about 2% per decade. In accord with all reports in the literature, the size of the ventral pons was unrelated to age. The volume of the cerebellar hemispheres, the vermis, and the ventral pons were larger in men, even after adjustment for height. The magnitude of the sex difference was the largest in the hemispheres and the anterior vermis, and the smallest in the lobules VI-VII (declive-folium-tuber). Moderate age-related shrinkage of the cerebellum and lack of age-related differences in the ventral pons are robust phenomena. However, in all likelihood, the effects of age on the cerebellum are not differential but uniform. The cerebellum and the pons are larger in men than in women and the difference is especially pronounced in the cerebellar hemispheres and the anterior vermis.