ABSTRACT
This chapter reviews the predominant etiological models for posttraumatic stress disorder (PTSD)/substance use disorder (SUD) and is written with several key assumptions in mind. It discusses evidence for explanatory models of PTSD/SUD, with the understanding that there is no single best model, but complementary explanations across multiple models. The chapter aims to understand the etiological and maintenance factors contributing to the onset of comorbid PTSD/SUD. The shared liability model suggests that PTSD and SUD frequently co-occur due to common familial risk. Substance use phenotypes have generally demonstrated higher heritability rates compared to trauma and PTSD phenotypes. The self-medication hypothesis presumes that individuals with a history of trauma and/or PTSD are at increased risk for SUD due to repeated use of substances to cope with trauma-related symptoms. Several prospective, epidemiological studies have been conducted to examine patterns of association between PTSD and SUD.
