Evidence has suggested that risk for schizophrenia is likely to occur in non-psychotic first-degree relatives of patients with schizophrenia. On the other hand, schizotypal personality disorder is genetically related to schizophrenia. The aim of this study was to compare schizotypal traits (i.e., positive schizotypy, negative schizotypy, cognitive disorganization, and impulsive nonconformity) among patients with schizophrenia and their non-psychotic first-degree relatives as well as normal controls. Thirty-four patients with schizophrenia and 50 of their non-psychotic first-degree relatives as well as 34 normal controls were included in this study. The data were collected by the Oxford-Liverpool Inventory of Feelings and Experiences, short version (sO-LIFE). The results showed that the three groups were significantly different from each other regarding mean scores of schizotypal traits. Patients with schizophrenia and their non-psychotic first-degree relatives exceeded normal controls on schizotypal traits. Patients with schizophrenia had higher scores on total schizotypal traits, positive schizotypy, cognitive disorganization, and impulsive nonconformity than their non-psychotic first-degree relatives. The findings revealed that hereditary factors had an important role in the development of schizophrenia spectrum disorders, and it is explainable by the stress-vulnerability model.
