Neuropsychological deficits in Parkinson's disease patients with visual hallucinations.

Recent neuropathological and neuroimaging studies suggest the involvement of several temporal regions in Parkinson's disease (PD) patients with visual hallucinations (VH). We examined 24 nondemented PD patients with VH, 21 PD patients without VH, and 21 healthy controls using a battery of tests assessing different aspects of temporal lobe function. PD patients with VH showed poorer performance in language, verbal learning, semantic fluency, and visuoperceptive functions compared to controls and PD patients without VH. Differences in verbal learning and visuoperceptive functions were independent of general cognitive status, disease severity, and depression. We suggest that a wide range of neuropsychological deficits can contribute to the emergence of VH in PD.