A comprehensive new study confirms that depression significantly increases the risk of dementia—not only in older adults but also those experiencing it earlier in life. Researchers at the University of Nottingham, University of Adelaide, and Curtin University synthesized data from past meta-analyses and recent cohort studies, concluding that depressive symptoms in both midlife (ages 40–60) and late life are linked to a higher risk of dementia.

The analysis supports earlier findings from twin and population-based studies, which found midlife depression raised vascular dementia risk, while late-life depression was more closely tied to Alzheimer’s disease. A Danish nurses’ cohort of over 25,000 women reported that those with mid- or late-life depression had over a fivefold increased risk of developing dementia—especially vascular dementia.

Experts suggest that depression contributes to dementia through mechanisms like chronic inflammation, vascular damage, and hormonal imbalances, such as cortisol dysregulation. Meanwhile, late-life depressive episodes could also signal prodromal dementia.

These findings underscore the vital importance of early detection and treatment of depression, not only for mental well-being but also as a critical dementia prevention strategy. Investing in mental-health support across the life span could help reduce future dementia burden.