GOAL: We hypothesized that right-handers schizophrenia patients would be more probable to present the normal brain asymmetry, and therefore their cognitive function could be more similar to that of the normal controls. Thus, the present study aims to compare the cognitive functioning between right-handed schizophrenic patients and normal right-handed comparing group, balanced by sex, educational level, and socioeconomic situation. METHODS: Twenty-five (12 men and 13 women) right-handed schizophrenia patients and 35 (19 men and 16 women) right-handed young adults were included in a cross-sectional design. The manual preference was evaluated with the Edinburgh Handedness Inventory, and cognitive performance with a series of neuropsychological tests. Family history of left-handedness and educational attainment were also analyzed. RESULTS: The right-handed schizophrenia patients showed poorer performance in 10 of 12 cognitive tests. Cognitive deficit (scores bellow cutoff in 50% of tests) was present in 60% of the patients with schizophrenia. Among demographic and clinical variables, only diagnostic category and educational level showed significant association with cognitive deficit in a logistic regression analysis. Family history of left-handedness and educational attainment were similar between groups. CONCLUSION: These findings suggested a more diffuse impairment of the cognitive functions, including language, among right-handed schizophrenia patients. Their performance was significantly different from that of the normal group. Our hypothesis of cognitive similarity between right-handed schizophrenics and healthy individuals was refuted.
Schizophrenia; manual preference; cognitive function; laterality
