A study published online first in the Archives of Neurology has suggested that depression is associated with prevalent mild cognitive impairment and an increased risk of dementia in Medicare recipients of 65 years and older.
It has been reported that depressive symptoms occur in 3–63% of patients with mild cognitive impairment and some studies have shown an increased dementia risk in individuals with a history of depression. The mechanisms behind the association between depression and cognitive decline have not been made clear and different mechanisms have been proposed, according to the study background.
Edo Richard, University of Amsterdam, the Netherlands, and colleagues evaluated the association of late-life depression with mild cognitive impairment and dementia in a group of 2,160 community-dwelling Medicare recipients.
“We found that depression was related to a higher risk of prevalent mild cognitive impairment and dementia, incident dementia, and progression from prevalent mild cognitive impairment to dementia, but not to incident mild cognitive impairment,” the authors said.
Baseline depression was associated with prevalent mild cognitive impairment (odds ratio 1.4) and dementia (2.2), while baseline depression was associated with an increased risk of incident dementia (hazard ratio 1.7) but not with incident mild cognitive impairment (0.9). Patients with mild cognitive impairment and coexisting depression at baseline also had a higher risk of progression to dementia (hazard ratio 2.0), especially vascular dementia (4.3), but not Alzheimer disease (1.9), according to the study results.
“Our finding that depression was associated cross sectionally with both mild cognitive impairment and dementia and longitudinally only with dementia suggests that depression develops with the transition from normal cognition to dementia,” the authors concluded.