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-IV). 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.

Revisiting the blurry boundaries of schizophrenia: spectrum disorders in psychometrically identified schizotypes.

Certain Personality Disorders (PDs) have been found to be present in the prodromal phase of schizophrenia at a higher rate than other personality disorders. Although schizotypal, paranoid, and schizoid PDs are traditionally viewed as spectra for schizophrenia, research suggests that avoidant PD should be included in this group (e.g., Fogelson et al., 2007). The present study examines whether a sample of psychometrically identified schizotypes (SZT) have higher incidence of schizophrenia-spectrum PDs, as well as more symptoms of these PDs, in general, than does a matched comparison (MC) sample. Eighty-five SZT and 78 MC participants were administered the Personality Disorder Interview for DSM-IV (PDI-IV) to assess PD symptoms and diagnoses. Results indicate that the SZT group evidenced significantly more symptoms of avoidant, schizoid, paranoid, and schizotypal PDs than did the MC group. Further, there were significant differences in the incidence of these PDs between the groups.

Season of birth, mixed-handedness, and psychometric schizotypy: preliminary results from a prospective study.

Season of birth and hand preference were examined in a sample of 42 (7 males, 35 females) individuals who were identified as schizotypic based on their scores on selected scales of the Chapman Psychosis Proneness Scales (CPPS) and a matched comparison sample of 42 individuals with non-deviant CPPS scores. Presence or absence of schizotypy was analyzed using chi square tests of independence with the presence or absence of each risk factor serving as the independent variable. Further analyses incorporated independent means t tests to examine mean scores on the CPPS with the presence or absence of each risk factor again serving as the independent variable. Results supported the hypothesis that winter/early-spring birth would be associated with psychometric schizotypy, although the results for mixed-handedness fell just short of statistical significance. However, mixed hand preference was associated with higher scores on MagId and PerAb scales of the CPPS, but not the RSA scale, which suggests that mixed laterality is associated with the more cognitive-perceptual aspects of schizotypy. Results are discussed in relation to previous literature and their relevance to the prediction of schizophrenia-related psychosis.