Neuropsychological functioning of dementia patients with psychosis

The current research sought to test the hypothesis that psychotic symptoms in patients with dementia might be due to relatively greater executive control and visuoperceptual deficits. Twenty-four dementia patients with psychosis and 24 outpatients without psychosis diagnosed with either probable Alzheimer's disease (AD) or possible/probable Ischemic Vascular Dementia (IVD) were studied. Groups did not differ with respect to age, education, severity of dementia, or depression. Presence and severity of psychosis was measured with a modification of the Neuropsychiatric Inventory (NPI; Cummings, J. L., Mega, M., Gray, K., Rosenberg-Thompson, S., Carusi, D. A., & Gorbein, J. (1994). The neuropsychiatric inventory: Comprehensive assessment of psychopathology in dementia. Neurology, 44, 2308-2314). Between-group and regression analyses found a consistent relationship such that patients with psychosis obtained low scores on the Boston Revision Wechsler Memory Scale-Mental Control subtest (WMS-MC subtest), a test of executive control. On some analyses patients with psychosis also made more perceptual errors on tests of naming and obtained higher scores on tests of delayed recognition memory. However, the relationship between severity of psychosis and performance on visuoperceptual and memory measures was considerably less robust. These data suggest a strong relationship between severity of psychosis and poor performance on executive control. Less evidence was obtained to support our contention that psychotic symptoms in dementia may arise from an interaction of neuropsychological deficits involving greater impairment in executive and visuoperceptual functioning.