Schizotypy and personality profiles of Cluster A in a group of schizophrenic patients and their siblings

BACKGROUND: Schizotypy, or the set of personality traits related to schizophrenia, is considered an endophenotypic manifestation that is more represented in first-degree relatives of patients with schizophrenia than in the general population. The assessment of schizotypy is primarily based on self-reports, and for this reason it presents several limitations. In order to assess schizotypy, this study proposes a diagnostic instrument based on clinical reports. METHODS: A sample of 66 subjects, composed of 25 outpatients with schizophrenia, 18 siblings of these patients and 23 healthy controls, was subjected to the personality assessment test SWAP-200 by trained clinical interviewers. To test the hypothesis of the difference between the profiles of the Personality Disorders within the schizophrenia spectrum, a Multivariate Analysis of Variance and subsequent planned comparisons were conducted. RESULTS: Patients with schizophrenia scored higher than both their siblings and the controls on all SWAP-200 scales; their siblings, compared to the healthy controls, showed significant statistical differences, with higher mean scores for paranoid (F((1,63)) = 7.02; p = 0.01), schizoid (F((1,63)) = 6.56; p = 0.013) and schizotypal (F((1,63)) = 6.47; p = 0.013) traits (PD T scores of Cluster A and Q-factor scores for the schizoid scale [F((1,63)) = 6.47; p = 0.013]). CONCLUSIONS: Consistent with previous data, first-degree relatives of patients with schizophrenia scored higher on schizophrenia-related personality traits than a general population comparison sample. SWAP-200, as an alternative diagnostic instrument to self-report measures, is able to reveal the higher prevalence of schizotypal traits in siblings of patients with schizophrenia, suggesting its possible use as a complementary instrument for the assessment of schizophrenia.