Identity as a key indicator of personality pathology in community and clinical samples: Developmental and clinical perspectives

The research field of personality pathology has increasingly moved towards dimensional approaches to operationalize personality disorders (PDs). Both the Diagnostic and Statistical Manual of Mental Disorders – fifth edition (DSM-5) and the International Classification of Diseases - 11th edition (ICD-11) have proposed models in which impairment in personality functioning (IPF) is assessed on a continuum to determine the severity of personality pathology. According to the DSM-5 and ICD-11 new PD models, one of the core elements of IPF is identity functioning. The emergence of these new dimensional models focusing on IPF raises new questions and offers new perspectives (and research opportunities) on personality pathology. First, the new PD models incorporate a developmental perspective on PDs, as the two domains of IPF (self- and interpersonal functioning) are core developmental tasks in adolescence (and beyond). Moreover, concurrently with the dimensional PD models, dimensional approaches to psychopathology in general are increasingly being proposed in the literature. This raises the question of how IPF (and identity functioning more specifically) is related to other transdiagnostic factors of psychopathology. Second, in order to be useful for clinical settings, it is necessary that assessment instruments for IPF are developed and psychometrically tested. Furthermore, it is important to investigate how concepts of these dimensional PD models relate to frameworks of existing treatments for PDs.

The present PhD project aims to address these questions and new research opportunities in the following three research objectives. The first objective is to psychometrically evaluate a short screening instrument for IPF, the Five-Item Screening Scale for Personality Disorder (FISSPD; Skodol et al., 2011), in both (adult and adolescent) community and clinical samples. In a second research objective, we will investigate how IPF develops in adolescence and emerging adulthood (short- and long-term)  and how it is associated to psychological symptoms in this developmental phase. In a third research objective, we will focus on the translation of the AMPD and ICD-11 PD models to Schema Therapy, which is a commonly used treatment for PDs. We will investigate associations between IPF, identity functioning, and (adaptive and maladaptive) schema modes in a community and clinical sample.

This project can contribute to the fields of clinical research and practice as it will provide a psychometric evaluation of a short screener to assess personality functioning. Additionally, it will provide useful information on the relations between IPF and Schema Therapy concepts, which may enhance clinical assessment and treatment decisions. Additionally, findings will give insight into the development of IPF in adolescence and emerging adulthood and its co-development/associations with psychopathology.