Cognitive performance and functional competence in coexisting dementia and depression.

Assessment was made of the impact of depression on the intelligence, memory, and functional competence of elderly community residents (aged 57-88 years) with senile dementia of the Alzheimer's type. Outpatients with either dementia (n = 21) or dementia coexisting with depression (n = 14) were given the Wechsler Adult Intelligence Scale (WAIS), Wechsler Memory Scale (WMS), and Dementia Rating Scale (DRS). No significant group differences were found for verbal IQ, performance IQ, or WMS memory quotient. Patients with coexisting dementia and depression earned significantly lower full scale IQ scores than patients with only dementia. Analysis of WAIS and WMS subtest scores and profiles revealed no difference between the two groups. Significant associations were found among the various cognitive measures and functional competence in both groups, but the patterns of these relationships differed. Intellectual measures accounted for the greatest proportion of functional competence variance in the patients with dementia, whereas memory measures accounted for the greatest proportion of variance in the patients with coexisting dementia and depression.