Relevance of Five-Factor Model personality traits for obsessive-compulsive symptoms in patients with psychotic disorders and their un-affected siblings

High rates of obsessive–compulsive symptoms (OCS) in schizophrenia require pathogenic explanations. Personality traits may represent risk and resiliency factors for the development of mental disorders and their comorbidities. The aim of the present study was to explore the associations between Five-Factor Model (FFM) personality traits and the liability for OCS in patients with psychotic disorders and in their un-affected siblings. FFM traits, occurrence and severity of OCS and (subclinical) psychotic symptoms were assessed in 208 patients and in 281 siblings. Differences in FFM traits between participants with vs. without comorbid OCS were examined and the predictive value of FFM traits on group categorization was evaluated. Associations between FFM traits and OCS severity were investigated. Patients and siblings with OCS showed significantly higher Neuroticism compared to their counterparts without OCS. Neuroticism was positively associated with higher OCS severity and significantly predicted group assignment in both patients and in siblings. Patients with comorbid OCS presented with lower scores on Extraversion and Conscientiousness. Higher Neuroticism, and to a lesser degree lower Extraversion and Conscientiousness might add to the vulnerability of patients with a psychotic disorder to also develop OCS. Future prospective studies are needed to elucidate proposed personality–psychopathology interrelations and possible mediating factors.