The relationship between substance use, prior trauma history, and risk of developing post-traumatic stress disorder in the immediate aftermath of civilian trauma

Many reports have documented the relationship between post-traumatic stress disorder (PTSD) and substance use. Substance use is commonly comorbid with PTSD and is a risk factor for trauma exposure. The aim of this study was to prospectively examine how recent substance use, abuse, or dependence influenced the development of PTSD in the context of a prior trauma history, including child abuse, and the severity of initial trauma reactions. Participants (N = 81) were recruited and assessed at the emergency department of a large urban hospital in Miami and serum levels of common drugs of abuse were measured. Although substance use appeared to be a risk factor for trauma exposure, neither self-reported nor blood toxicology influenced the development of PTSD. Positive toxicology screens were more likely to be associated with a diagnosis of substance abuse or dependence, χ2 (1) = 4.11, p = .04. Participants with a history of physical abuse were more likely to have a positive toxicology screen, χ2 (1) = 4.03, p = .05. The majority of our trauma-exposed subjects (66%) were found to be positive for one or more illicit substances at presentation at the ED. The current findings provide support for the “high risk” hypothesis in which substance use is associated with increased trauma exposure.