Neuropsychological predictors of dementia in late-life major depressive disorder.

OBJECTIVE: Major depressive disorder is a likely risk factor for dementia, but some cases of major depressive disorder in older adults may actually represent a prodrome of this condition. The purpose of this study was to use neuropsychological test scores to predict conversion to dementia in a sample of depressed older adults diagnosed as nondemented at the time of neuropsychological testing.
DESIGN: Longitudinal, with mean follow-up of 5.45 years.
SETTING: Outpatient depression treatment study at Duke University. PARTICIPANTS: Thirty nondemented individuals depressed at the time of neuropsychological testing and later diagnosed with incident dementia; 149 nondemented individuals depressed at the time of neuropsychological testing and a diagnosis of cognitively normal.
METHODOLOGY: All participants received clinical assessment of depression, were assessed to rule out prevalent dementia at the time of study enrollment, completed neuropsychological testing at the time of study enrollment, and were diagnosed for cognitive disorders on an annual basis.
RESULTS: Nondemented, acutely depressed older adults who converted to dementia during the study period exhibited broadly lower cognitive performances at baseline than acutely depressed individuals who remained cognitively normal. Discriminant function analysis indicated that 2 neuropsychological tests, Recognition Memory (from the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery) and Trail Making B, best predicted dementia conversion.
CONCLUSIONS: Depressed older adults with cognitive deficits in the domains of memory and executive functions during acute depression are at higher risk for developing dementia. Some cases of late-life depression may reflect a prodrome of dementia in which clinical manifestation of mood changes may co-occur with emerging cognitive deficits.