The Underlying Structure of Comorbid Mental Health and Substance Use Disorders in Prison Populations

Background: High rates of mental disorders have been reported for prison populations. Understanding patterns of comorbidity may be essential for the development of adequate treatment interventions. The present study aimed to assess the underlying structure of comorbidity between mental health and substance use disorders in prison populations. Methods: Current mental disorders were assessed using the Mini-International Neuropsychiatric Interview in a cross-sectional observational study of 427 individuals consecutively committed to prison facilities in Santiago, Chile. Five alternative structural models were tested using confirmatory factor analysis (CFA). Latent class analysis of comorbid mental health and substance use disorders was carried out. Results: CFA indicated the best fit for a bifactor model with a general psychopathology P factor and specific internalizing and externalizing factors. Borderline personality disorder loaded highest on the P factor (0.85). The latent comorbidity structure showed a four-class solution representing one class without relevant comorbidities (48% prevalence) and three classes representing the following comorbidities: (1) externalizing disorders including substance use and antisocial personality disorder (31%), (2) internalizing disorders including anxiety disorders (10%), and (3) all types of disorders co-occurring (11%). Major depression and borderline personality disorder were present across all three latent classes of comorbidity. Conclusions: Prison mental health services need to serve a highly comorbid population. Specific approaches may be useful for an externalizing and an internalizing spectrum of disorders. An important group of individuals with all types of mental disorders co-occurring may need new approaches in treatment development.