Handedness and schizotypy in nonpsychotic relatives of patients with schizophrenia

摘要

Existing studies have found the relationship between handedness and schizotypy to be inconsistent and had limited generalizability since only highly homogeneous groups have been investigated. This study aimed to examine the relation between handedness and the four schizotypal factors identified from a previous confirmatory factor analysis in a population of high familial loading for schizophrenia. Study subjects consisted of nonpsychotic first-degree relatives (850 parents and 334 siblings) of sib-pairs who were co-affected with schizophrenia. All participants were interviewed with the Diagnostic Interview for Genetic Studies, which contains a section of the modified Structured Interview for Schizotypy, and the Annett handedness questionnaire. Both categorical and continuous indicators for handedness were examined. Non-right handed siblings of schizophrenia patients displayed more positive schizotypal features than their right handed counterparts when the two-way Annett's handedness classification was adopted. No association was found when handedness was treated as continuous. The relationship between handedness and schizotypy was insignificant for parents probably due to the strong social pressure against left-handedness. We concluded that categorical non-right handedness was associated with positive schizotypy in nonpsychotic siblings of schizophrenia patients. The results indicate that an atypical cerebral lateralization underlying non-right handedness may be also a contributing factor to positive schizotypy.