UCLA researchers analyzed brain scans from nearly 1,500 adults to estimate brain age versus chronological age, creating a Brain Ageing Index. Higher BAI correlated with poorer memory, executive function and more depressive symptoms. In one group, stool analyses linked a specific gut bacterium and metabolites, fat molecules, a cholesterol-related compound and lower estetrol, to older-appearing brains, implicating immune, vascular and neuronal pathways.
