Neuropsychological test results associated with psychiatric disorders in adults.

This review addresses the question of whether neuropsychological tests can be used to discriminate between cerebral dysfunction and nonorganic psychiatric disorders. Considered are 94 studies that compared test scores of psychiatric patients with scores of brain-damaged patients or with established norms for organicity. Despite methodological inconsistencies and deficiencies across studies, most studies found that psychiatric diagnostic groups other than chronic or process schizophrenics performed better than organics on testing. Organic versus functional discrimination rates reported in these studies are similar to discrimination rates obtained by the tests when organics are compared with normal or general medical controls. Considered together with organicity base rate and error cost estimates, these discrimination rates are high enough to justify the use of most popular neuropsychological tests in psychiatric settings that do not have high proportions of chronic or process schizophrenics. The possibility is discussed that groups of chronic or process schizophrenics may look organic on neuropsychological tests because a significant proportion of such patients are organic.