Internalizing and externalizing personality subtypes predict differences in functioning and outcomes among veterans in residential substance use disorder treatment

There is a long history of using personality to subtype patients in treatment for substance use disorders (SUD). However, no one has validated a typology of SUD patients using a structural model of normal-range personality, particularly indicating whether subtypes differ on treatment processes and outcomes. We developed a personality-based typology among 196 military veterans enrolled in residential SUD treatment at a Veterans Affairs medical center. Patients were assessed at treatment entry, 1 month into treatment, and at discharge from treatment. Personality was assessed using the Multidimensional Personality Questionnaire-Brief Form at treatment entry. Latent profile analyses identified a 3-group solution consisting of low pathology, internalizing, and externalizing groups. The internalizing group scored lowest on measures of functioning at treatment entry, whereas the externalizing group scored more poorly on treatment processes and outcomes over the course of their residential stay (e.g., more stressful relationships with other residents, lower program alliance). These findings support a clinically meaningful typology of SUD patients based on a 3-factor model of personality and can serve as a guide for future efforts aimed at developing targeted interventions that can address the individual differences of patients in this population.