Motoric laterality and eye dominance suggest unique pattern of cerebral organization in schizophrenia

The performance of 26 young patients with early-onset schizophrenia on motoric laterality and eye dominance was compared with that of 24 psychiatric inpatients suffering from an early and diffuse brain damage, 16 nonpsychotic non-brain-damaged psychiatric inpatients, and 36 university students. All subjects were in late adolescence. These schizophrenic patients showed more left-sidedness on all the laterality measures. Left eye dominance was highly prevalent in the schizophrenic group (about 75% of the subjects) and had high diagnostic usefulness. In addition, laterality measures of the schizophrenic patients were highly incongruous. Our results support the hypothesis of a specific left hemispheric dysfunction in schizophrenia that is neither shared by all psychiatric patients nor resembles a generalized insult to the brain. Although the left hemispheric dysfunction in schizophrenia is considered to be neurological, the etiological contributions of brain insults and of genetic and environmental factors are unclear.