Lack of Premeditation Mediates the Relationship Between Adverse Childhood Experiences and Posttraumatic Stress Disorder in Individuals in Residential Treatment for Substance Use Disorder

<b>Objective:</b> Adverse Childhood Events (ACEs) are associated with increased vulnerability for posttraumatic stress disorder (PTSD), but not everyone who experiences ACEs develops PTSD. Impulsivity has gained interest as a potential mediator between ACEs and PTSD, given that both PTSD and ACEs have been closely related to impulsivity. However, less is known about the relationship within the context of substance use disorder (SUD), a population highly vulnerable to co-occurring PTSD. This study examined whether impulsivity mediates the relationship between ACEs and PTSD symptoms in adults seeking residential treatment for substance use disorder (SUD). <b>Methods:</b> <i>N</i> = 134 consenting adults in residential treatment for SUD completed questionnaires measuring impulsivity (UPPS-P), ACEs (ACEs Scale), and PTSD symptoms (PCL-5). Regression models tested our hypotheses that ACEs would predict PTSD symptoms and that impulsivity would mediate this relationship. <b>Results:</b> Two-thirds of participants met the PCL-5 score threshold for a provisional diagnosis of PTSD. ACEs score and impulsivity were significant direct predictors of PTSD symptoms (coeff = 2.23, <i>p</i> < .001; coeff = 1.03, <i>p</i> < .001). Among UPPS-P subconstructs, only lack of premeditation emerged as a partial mediator (z = 2.14, <i>p</i> = 0.032). <b>Conclusions:</b> Individuals with SUD experience adverse and traumatic events at alarming rates and are at increased risk for PTSD. Our mediation finding suggests that impulsivity and especially lack of premeditation may be clinically relevant in the development or maintenance of PTSD symptoms among individuals with SUD.