PREVALENCE AND CORRELATES OF MIXED-HANDEDNESS IN SCHIZOPHRENIA

Increased rates of nonright-handedness have been reported in schizophr enia, but a dear distinction has not been made between left- and mixed -handedness. Handedness preferences in 96 patients fulfilling DSM-III criteria for schizophrenia and 43 normal comparison subjects were asse ssed with the Edinburgh Handedness Inventory. A 100% criterion was use d to establish left- and right-handedness. Results were analyzed with Mantel-Haenszel odds ratios adjusted for age and sex. The schizophreni c group showed a significant increase in the proportion of mixed-hande rs compared with the normal group. There was no increase in pure left- handedness in the schizophrenic relative to the normal group. Mixed-ha ndedness in the schizophrenic patients was significantly associated wi th chronicity of illness. Mixed-handed patients were less likely to ha ve a family history of psychotic illness than patients with strong rig ht- or left-handedness, The results indicate a neurodevelopmental rath er than a genetic origin for anomalous lateralization in schizophrenia .