Neuropsychiatric impairments as predictors of mild cognitive impairment, dementia, and Alzheimer's disease.

In this study, the relations between cognitive status and neuropsychiatric impairments in nondemented older adults in cross section and over time is examined. Using data from the Canadian Study of Health and Aging (CSHA), a longitudinal, nation-wide study in which data were collected 3 times (ie, CSHA-1, CSHA-2, CSHA-3) at 5-year intervals, individuals were classified with (n = 240) and without (n = 386) cognitive impairment at CSHA-2. Loss of interest, changes in personality and mood, and depression were reported by a knowledgeable informant (ie, family or friends) more frequently for those with cognitive impairment than for those without cognitive impairment. After controlling for initial cognitive status, loss of interest and depression contributed significantly to the prediction of mild cognitive impairment, dementia, and Alzheimer's disease over time. These findings suggest that these neuropsychiatric impairments play significant roles throughout the course of cognitive decline and should be taken into consideration even before cognitive impairment is evident.