Date of Award

2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

Abstract

Schizophrenia is a severe mental illness for which the etiology is still largely unknown. However, one of the most prominent etiological hypotheses involves endophenotypes, which are seen as subtle signs and indicators that may denote susceptibility to developing the disorder. Among the endophenotypes associated with schizophrenia are premorbid personality disturbances. Namely, there is research to suggest that certain personality disorders (i.e., schizotypal, schizoid, paranoid, and avoidant) are present at a greater frequency than other personality disorders in the prodromal phase of schizophrenia. Research indicates that significantly more symptoms of these personality disorders are seen in a schizotypic college student population when using the Personality Disorder Interview for DSM-IV (PDI-IV) (Bolinskey et al., 2015). However, the Structured Clinical Interview for DSM-IV Axis II (SCID-II) is a more widely used measure for diagnosing personality disorders. A comparison of hit rates of the PDI-IV and the SCID-II is needed to identify premorbid personality disturbances of schizophrenia. The present study found that individuals identified as hypothetically psychosis-prone endorsed more symptoms and met criteria more often on the four personality disorders examined on both the SCID-II and the PDI-IV than their matched controls. The SCID-II produced a lower hit-rate for some diagnoses than did the PDI-IV. In addition, positive correlations were found between the SCID-II and two measures of schizotypy. The present study provides further evidence for personality disturbance as an endophenotypic marker of schizophrenia and adds to the psychometric evidence for the construct of schizotypy.

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