Widespread brain shrinkage drives aging-related memory decline, mega-analysis finds

An international mega-analysis of over 10,000 MRI scans and 13,000 memory tests from thousands of healthy adults shows that memory decline with age stems from broad structural brain changes across many regions—especially, but not exclusively, the hippocampus—with nonlinear acceleration in later life and not fully explained by Alzheimer's risk genes like APOE ε4. This points to a distributed brain vulnerability that could help identify at-risk individuals and guide personalized cognitive health interventions.