Depression and the risk for dementia

Abstract

Depression is associated with increased risk of subsequent development of dementia; however, the nature of the association is still poorly understood. The purpose of the review was based on recent studies to discuss whether depression is a prodromal state of dementia or an independent risk factor for dementia, as well as to discuss how the type of depression, the type of dementia, and antidepressant treatment influence the association. Findings from recent studies suggest that some forms of depressive illness, for example early-onset depression before age 65 years and recurrent depression, may constitute long-term risk factors for development of dementia, whereas the onset of more recent depressive symptoms may reflect a prodromal phase of dementia. It is not clear whether specific subtypes of depression correspond to specific types of dementia. Recent studies suggest that long-term treatment with antidepressants may decrease the risk of developing some types of dementia, depending on the type of depressive disorder. This review has shown that the type of depression and dementia, as well as the effect of drug treatment, has to be considered to improve knowledge on the association between depression and dementia.