Abstract
Background: Comorbid borderline personality disorder (BPD) in psychosis is poorly understood, despite research suggesting that it contributes to poorer outcomes at 5 and 10-year follow-up. Mentalizing (the ability to attribute thoughts and feelings to self and others) is thought to be a transdiagnostic factor that contributes to core impairments in BPD and symptoms of psychosis. This study aimed to explore the relationship between mentalizing, positive and negative symptoms of psychosis, and traits of borderline personality disorder, in a sample of patients with first-episode psychosis, and in a non-clinical sample. Method: 32 adults with first-episode psychosis (FEP) and 149 non-clinical participants were assessed using the reflective functioning questionnaire (RFQ). The RFQ measures two dimensions of mentalizing, certainty (RFQc) and uncertainty (RFQu) about mental states. Traits of BPD and symptoms of psychosis were measured using the self-report version of the Zanarini rating scale for BPD, the Community Assessment of Psychic Experiences (CAPE), and the Green et al, paranoid thought scale. Results: Patients with FEP were significantly more impaired on the RFQ compared to the non-clinical sample, showing significantly lower certainty, and higher uncertainty about mental states. Regression analysis showed significant associations between higher scores on the RFQu and negative symptoms of psychosis in both groups. Significant associations were also found between higher RFQu and increasing BPD traits in the non-clinical sample. Conclusions: The present research provides evidence that impairments in mentalizing may be a core component of the process underlying negative symptoms of psychosis across both clinical and non-clinical samples. Mentalizing impairments may also be associated with BPD traits, but this finding was only confirmed in the non-clinical sample. Mentalizing should therefore be considered in the early assessment and treatment of patients experiencing these difficulties.