Personality in patients with substance use disorders according to the co-occurring severe mental illness: A study using the alternative five factor model

Personality plays an important role in individuals with Substance Use Disorder (SUD) and co-occurring Severe Mental Illness (SMI). However, the possible personality differences in SUD patients considering their co-occurring SMI remain unknown. We explored the personality in a sample of 104 male patients with SUD and SMI: 35 had co-occurring Schizophrenia (SZ +), 32 had Bipolar Disorder (BD +), and 35 had Major Depressive Disorder (MDD +). We followed the Alternative Five Factor Model and used the Zuckerman-Kuhlman Personality Questionnaire. Moreover, we examined the relationship among SUD and SMI variables, and personality. The type of co-occurring SMI modulates the Neuroticism-Anxiety, Sociability, and Impulsivity Sensation-Seeking personality traits. BD + patients were characterized by a higher Neuroticism-Anxiety than MDD +, and a higher Impulsivity Sensation-Seeking than SZ + and MDD +. Manic symptoms were positively linked to Neuroticism-Anxiety for BD +. Patients with SZ + showed a lower Sociability than BD +, and an older age of SUD onset was related to a higher sociability for SZ +. Overall, SUD treatment for BD + patients should emphasize strategies to manage negative emotions and impulsivity. Our results underline the importance of a dimensional understanding of personality among patients with SUD and co-occurring SMI, which could inform of specific approaches to improve their treatment and prognosis.