A massive international brain study has revealed that memory decline with age isn’t driven by a single brain region or gene, but by widespread structural changes across the brain that build up over time. Analyzing thousands of MRI scans and memory tests from healthy adults, researchers found that memory loss accelerates as brain tissue shrinkage increases, especially later in life. While the hippocampus plays a key role, many other brain regions also contribute, forming a broad vulnerability rather than isolated damage.