Schizophrenia spectrum personality disorders in psychometrically identified schizotypes at two-year follow-up

Earlier (Bolinskey et al., 2015), we reported that psychometrically identified schizotypes displayed greater symptom levels and higher incidences of schizophrenia spectrum (schizotypal, schizoid, paranoid, and avoidant) personality disorders (PDs). In this study, 49 schizotypes and 39 matched controls participated in follow-up assessments after two years. Participants were previously identified as schizotypes or controls based on scores on the Chapman Psychosis Proneness Scales (CPPS), and were interviewed at baseline and follow-up with the Personality Disorder Interview for DSM-IV (PDI-W). At follow-up, schizotypes displayed significantly higher symptom levels compared to controls, with medium to large effects, and appeared to meet criteria for diagnosis of each PD more often than controls, although significant differences were only observed for paranoid PD. Overall, schizotypes were more likely to have met criteria for a diagnosis at either baseline or follow-up. Finally, we observed a widening disparity over time between schizotypes and controls in avoidant and schizoid PDs. These results suggest that schizophrenia spectrum PDs, as well as subthreshold symptoms of these disorders, can represent a greater liability for schizophrenia in individuals identified as at-risk on the basis of psychometric means only. Furthermore, these findings demonstrate that such differences persist, and in some cases increase, over time.