Hand preference in schizophrenics and handedness conversion in their childhood

A handedness questionnaire which was given to 1774 schizophrenic inpatients was identical to that employed in our previous study on healthy students. Information was obtained on forced conversion of hand usage in childhood and the occurrence of left-handedness in their families. Family history of schizophrenia was also investigated. There were no significant differences in the prevalence of left-handedness or non-right-handedness (i.e., left-handedness and ambidexterity combined) between schizophrenic patients and normal subjects. However, the rate of converted right-handedness in schizophrenics was higher than that in normal people. The incidence of original non-right-handedness (i.e., present non-right-handedness and converted right-handedness combined) in schizophrenics was greater than that in normal controls.