Dementia of depression among patients with neurological disorders and functional depression.

Cognitive performance on the Mini-Mental State Examination (MMSE) was assessed in depressed patients (diagnosis of major depression) with cerebrovascular lesions, with Parkinson's disease, or with functional depression (no known brain lesions). Controls for patients with brain lesions or Parkinson's disease were nondepressed patients with the same conditions. Controls for functionally depressed patients were age-matched normal individuals. Depressed patients had significantly lower total MMSE scores than their nondepressed counterparts, but depression did not have an effect on cognitive performance across the three disease groups. The only significant difference between depressed and nondepressed patients shared by all three groups was poorer performance by depressed patients on the delayed-recall task. The findings suggest that major depression may lead to a specific pattern of cognitive deficits independent of coexisting brain pathology.