Sex Differences in Neuropsychological Functioning Among Schizophrenia Patients

Abstract

Evidence from the literature addressing sex differences in cognition in schizophrenia remains equivocal, with some researchers suggesting that male schizophrenia patients are more impaired than female subjects, while others report no significant sex differences in cognitive functioning. The aim of the present study was to investigate whether the differential pattern of cognitive performance observed in healthy men and women is preserved in male and female schizophrenia patients. Ninety-six schizophrenia patients (56 men) were compared with 62 age- and gender-ratio matched healthy controls (31 men), on a battery of neuropsychological tests that assessed basic cognitive abilities: attention, working memory, abstraction, inhibition, fluency, verbal learning and memory, visual memory, visuospatial skills, and psychomotor speed. As a group, schizophrenia patients were significantly impaired in each of the cognitive domains assessed, with the exception of psychomotor speed. The effect of sex was significant for verbal learning and memory, wherein women outperformed men. No significant group x sex interactions were found in any cognitive domains, indicating that the female advantage typically observed in verbal learning and memory remained the same in the schizophrenia patients. The degree of cognitive impairment is the same for male and female schizophrenia patients. Those sex differences found among the patients were typical of the healthy population as well. Therefore, differential decrements in basic cognitive domains do not appear to account for the favourable course of schizophrenia in women relative to men.