Abstract
The psychotic features of schizophrenia and the motor problems of Parkinson's disease, respectively, allow striking contrasts to be made between the two disorders. However, it has recently become apparent that the two groups of patients share problems of mentation that are best explained by some dysfunction of the prefrontal cortical areas of the brain. These commonalities are addressed in terms of neurobiological fact and psychological theory, providing possible insight into the neuropsychology of schizophrenia and its dichotomous nature. In particular, the putative role of abnormal frontostriatal interactions in the two disease states is emphasized.