Cognitive impairment in schizophrenia.

The cognitive functioning of 62 schizophrenic subjects was compared with that of 42 normal controls using neuropsychological tasks that included assessment of soft neurological signs, an aphasia screening test, tachistoscopic stimulation, auditory threshold determinations, and items from the Mini-Mental State, Halstead-Reitan, and Luria-Nebraska batteries. Performance was rated blindly for hemispheric, regional cortical, and global impairment. No control showed more than a mild deficit, whereas three-quarters of the schizophrenic patients exhibited moderate to severe dysfunction. Schizophrenic subjects differed significantly from controls on all measures and showed bilateral impairment that was comparatively worse in the dominant frontotemporal regions. These differences were not a function of age, sex, handedness, or drug administration.