The validation of the Personality Inventory for DSM-5 (PID-5) and the relation of PID-5 Psychoticism to psychosis

Summary

The Personality Inventory for DSM-5 (PID-5; Krueger et al., 2012) is a self-report questionnaire that originates from the preparatory work of the DSM-5 Task Force, aligning the classical DSM-IV-TR personality categories with a dimensional representation of personality pathology. Inspired by the non-clinical Five Factor Model (FFM; Costa & McCrae, 1992), its 25 primary scales have been reported to group into five higher order factors, each representing a pathological version of the classic five personality dimensions (i.e., Neuroticism, Extraversion, Agreeableness, Conscientiousness and Openness). The present PhD thesis contributes to the ongoing PID-5 research by investigating the merits of the PID-5 in a clinical population and its advantages over the Dimensional Assessment of Personality Pathology Basic Questionnaire (DAPP-BQ; Livesley & Jackson, 2009) as a representative of the pathological four dimensional model (Openness not included). Indeed, whereas earlier studies have found solid pathological equivalents for four out of five of the classical Big Five personality dimensions, an unequivocal pathological version of the fifth personality dimension Openness, i.e. Psychoticism, remains subject of ongoing research. Also, the conceptual relationship between Psychoticism as a personality factor, syndromal psychosis and cognitive biases as an at-risk factor for syndromal psychosis warrants further investigation. In the present PhD thesis we will start from a separate psychometric evaluation of each of the new instruments that will be used in addressing our research questions. This will include the psychometric evaluation of the PID-5 itself, as well as the psychometric evaluation of the Davos Assessment of Cognitive Biases Scale (DACOBS; van der Gaag et al., in press), an instrument measuring cognitive biases as a mediating personality trait in the development of syndromal psychosis. Thereafter, we will focus on the incremental validity of the fifth personality dimension Psychoticism (above and beyond the four other personality traits) in the prediction of (1) psychopathology in general,  and (2) psychosis in particular, and on its conceptual relationship with cognitive biases as an at-risk factor for syndromal psychosis.