In the quiet architecture of memory, a team of USC neuroscientists has found that depression leaves a measurable imprint on a specific chamber of the hippocampus — the CA23DG subfield, responsible for retrieving memories and telling similar experiences apart. Studying over two thousand older adults, they discovered this structural difference persists even after accounting for the known biological signatures of Alzheimer's disease, suggesting depression carves its path through the brain by its own distinct routes. The finding does not yet tell us whether depression causes this shrinkage or what