Imbalance of hemispheric functions in the major psychoses: a study of handedness in the People's Republic of China.

A study of hand preference and eye dominance in schizophrenia, manic-depressive psychosis, and normal controls was carried out in the People's Republic of China. An excess of sinistrality was found in both men and women schizophrenics, but not in manic-depressive patients. Both the manic-depressive and schizophrenic psychoses are characterized by a significant excess of left eye dominance and by an increasing divergence between eye and hand dominance when compared to the controls. The major published studies investigating hand preference in psychopathology are reviewed, and possible interpretations of the conflicting findings are suggested.