A review of neuropsychological differences between paranoid and nonparanoid schizophrenia patients.

This review examines the literature on neuropsychological differences between paranoid and nonparanoid schizophrenia subjects. Thirty-two studies related to intellectual functioning, attention, memory, language, visual-spatial, and motor functions are discussed. Subjects with paranoid schizophrenia did not demonstrate higher intellectual functioning than those with nonparanoid schizophrenia, and both groups performed similarly on tests of verbal ability and visual-spatial functions. Several studies suggest that the paranoid subtype is associated with higher performance on tests of executive functions, attention, memory, and motor skills. However, the findings are inconsistent. Methodological issues in the literature are examined, including varying degrees of participants' chronicity and severity of illness among studies, criteria for diagnostic group membership, medication effects, reliability and validity of the neuropsychological measures, and statistical power.