The factor structure of schizophrenia spectrum personality disorders: signs and symptoms in relatives of psychotic patients from the UCLA family members study

The dimensions and limits of the concept of schizotypy are examined using an exploratory factor analysis of the 36 signs and symptoms in the Cluster A DSM-III-R personality disorders as well as those in Borderline Personality Disorder and Avoidant Personality Disorder in the 307 first-degree relatives and half-siblings of 123 probands with schizophrenia/schizoaffective disorder. The personality disorders examined were assessed using sections of the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID-II) and hospital and clinic records. Interviewers were blind to the proband diagnosis. The resulting six-factor solution accounted for 40% of the variance. The results of the six-factor solution accounted for the greatest variance and gave the most easily interpretable simple structure of all the solutions examined. The six factors are labeled as (1) Borderline Symptoms, (2) Schizoid Symptoms, (3) Paranoid Symptoms, (4) Avoidant Symptoms, (5) Positive Schizotypy Symptoms, and (6) Disorganized Symptoms. The Schizotypal Personality items are spread across all but the 'Borderline Symptoms' factor. We conclude schizotypy is a multidimensional construct that is not adequately characterized by any one DSM-III-R personality disorder. It appears to consist of six distinct dimensions, which, interestingly, parallel current thinking on dimensions in schizophrenia.