The Kings Schizotypy Questionnaire as a quantitative measure of schizophrenia liability

We used a new self-report measure, the Kings Schizotypy Questionnaire (KSQ; Williams, M. The psychometric assessment of schizotypal personality. PhD thesis. Institute of Psychiatry, University of London, 1993), to investigate schizotypy as a quantitative measure of familial liability to schizophrenia. The KSQ was administered to 135 DSM-IV schizophrenia probands, 153 of their healthy first-degree relatives, and 267 control subjects. We found that the questionnaire clearly differentiated schizophrenic from non-schizophrenic individuals, but failed to differentiate the relatives from controls. Possible reasons for this include defensive responding among relatives, self-selection bias among relatives, differences in data collection methods, and the possibility that positive aspects of schizotypy may not be closely related to familial liability to schizophrenia. (C) 2000 Elsevier Science B.V.