Date of Award

2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

Abstract

Depersonalization Disorder (DPD) is considered both under-researched and underdiagnosed. A variety of reasons have been proposed for the under-diagnosis of DPD, including the high frequency of depersonalization as a symptom and comorbidity of DPD with other disorders. Under-diagnosis of DPD has also been attributed to inadequate diagnostic criteria in the DSM-IV-TR, as it lists only four criteria and only one specifically addresses the phenomenon of depersonalization. Several groups of researchers have proposed more comprehensive and in-depth conceptualizations of DPD. Further, common biases in clinical decision-making, such as an over-reliance on cognitive heuristics and the use of prototypes, can contribute to inaccurate diagnosis and under-diagnosis. A national sample of licensed psychologists was randomly selected and recruited from the membership of the American Psychological Association. The study was conducted on-line and participants were asked to read one of two DPD cases, assign a diagnosis, and rate the representativeness of a series of diagnoses for the case. They were also asked to rate the presence of a list of symptoms, including the DSM-IV-TR and ICD-10 criteria for DPD, and the symptoms and dimensions of DPD and depersonalization from the literature. Half of the participants were asked to assign a diagnosis and then rate symptoms (simulated prototype approach) while the others rated the symptoms before assigning a diagnosis (simulated DSM-IV approach). The study found that clinicians under-diagnosed DPD and that the DSM-IV depersonalization criterion had high sensitivity but not adequate specificity. Results indicated that a simulated DSM-IV approach improved accuracy of diagnosing DPD. Finally, results indicated that the symptoms of DPD and depersonalization proposed by researchers had better predictive value for DPD representativeness ratings than the current DSM-IV criteria, but not for a diagnosis of DPD. The results of this study have implications for the diagnostic criteria for DPD, clinical decision-making strategies, clinical training, and future research on DPD.

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