Background: An excess of mixed-handedness has been repeatedly reported in schizophrenia and schizotypy. Handedness is a measure of atypical cerebral lateralization, which is considered as a risk factor for schizophrenia. Several studies have attempted to identify correlations between handedness and dimensions of psychosis but the results obtained so far remain inconclusive.
Objective: To explore a possible link between mixed-handedness and the three classical dimensions of psychosis. As speech and language disorders may be associated with cerebral lateralization, we predicted a correlation between mixed-handedness and disorganized dimension.
Methods: We used the Schizotypal Personality Questionnaire (SPQ) and the Edinburgh Handedness Inventory (EHI) to study the correlation between mixed-handedness scores and positive, negative or disorganized dimensions in a sample of 62 healthy subjects.
Results: We found a negative correlation between mixed-handedness and the disorganized dimension of schizotypy, as individuals with prominent mixed-handedness showed more severe disorganization.
Conclusion: We have identified a link between mixed-handedness and the disorganized dimension that may help to identify genetic vulnerability factors involved in psychosis.