In a study, depression in a group of Medicare recipients ages 65 and older appeared to be associated with prevalent mild cognitive impairment and an increased risk of dementia.
Depressive symptoms occur in 3% to 63% of patients with mild cognitive impairment, based on previous studies, and some studies showed an increased dementia risk in individuals with a history of depression, according to background information in the study, which appeared Dec. 31 on the website of JAMA Neurology (formerly known as the Archives of Neurology).
The mechanisms behind the association between depression and cognitive decline have not been made clear and different mechanisms have been proposed, the researchers added.
Edo Richard, MD, PhD, of the University of Amsterdam in the Netherlands, and colleagues evaluated the association of late-life depression with MCI and dementia in a group of 2,160 community-dwelling Medicare recipients.
The researchers reported that depression was related to a higher risk of prevalent MCI and dementia, incident dementia and progression from prevalent MCI to dementia, but not to incident MCI. (Prevalent cases are those that developed before the study, while incident cases developed during the study period.)
Baseline depression was associated with prevalent MCI and dementia, as well as with an increased risk of incident dementia but not with incident MCI. Patients with MCI and coexisting depression at baseline also had a higher risk of progression to dementia, especially vascular dementia, but not Alzheimers disease, according to the study results.
“Our finding that depression was associated cross-sectionally with both MCI and dementia and longitudinally only with dementia suggests that depression develops with the transition from normal cognition to dementia,” the authors concluded.
The study abstract is available at http://archneur.jamanetwork.com/article.aspx?articleid=1542838.