Aging hippocampus and amygdala.

Earlier studies suggest that the anterior hippocampus may show resilience to age-associated volume loss. This study compared high-resolution magnetic resonance images obtained from younger (n=28; age range: 22-50 years) and older (n=39; age range: 65-84 years) healthy right-handed individuals to determine whether age-related volume changes varied between the hippocampal head, body and tail. Volumetric reductions were progressively more severe from hippocampal head to tail. Amygdala volume differences were intermediate in size. Although limited by the cross-sectional design, these data suggest that hippocampal subregions show a gradient of volume reduction in healthy aging that contrasts with the preferential reduction of anterior hippocampal volumes in Alzheimer's and Parkinson's diseases.