Is There Atypical Handedness in Schizophrenia?

Ninety-three schizophrenic patients and 105 normal controls were tested in a single session on an 8-item repeat-administration handedness test. The schizophrenic group, in contrast to the normal controls, showed a shift in the distribution away from right-handedness, which was due to an increase in the proportion of mixed-handers. Additional analyses revealed that the increase in mixed-handedness was largely due to an increase of within-item variability in the schizophrenic group, which we refer to as ambiguous handedness. Nearly 20% of the schizophrenic patients were inconsistent on 3 or more items compared with 3.8% of the normal controls. This increased incidence of atypical handedness is discussed within the context of disorders of attention and neurodevelopment.