The interface of depression and dementia

The interface of depression and dementia is an enduring, difficult problem in psychogeriatrics. Cognitive impairment is one of the secondary criteria for major depression; and major depression may well be a risk factor for Alzheimer's disease. The influence of vascular disease on dementia and late-onset major depression is also compelling. However, depressive symptoms more often appear to be a prodrome of Alzheimer's disease or a complication of vascular dementia. Major depression and stroke may both accelerate the dementia process, but seem unlikely on the basis of single episodes to be a sufficient cause of dementia. The heterogeneity of signs, symptoms and neuropathology in both depression and dementia remain substantial obstacles to a clear understanding of the interface.