Neurocognitive Predictors of Treatment Outcomes in Psychotherapy for Comorbid PTSD and Substance Use Disorders

Objective: Comorbidity between posttraumatic stress disorder (PTSD) and substance use disorders (SUD) is common, and both are associated with cognitive dysfunction. However, few studies examine the impact of cognitive deficits on treatment outcomes. Here, we leverage data from a randomized clinical trial of integrated versus phased psychotherapy for SUD and PTSD to examine the relation of cognitive functioning to treatment response. Method: One-hundred and thirteen veterans with co-occurring PTSD and SUD completed Penn Computerized Neurocognitive Battery tests assessing attention, executive control, memory, and spatial processing. Linear mixed-effects models examined interactions between cognitive functioning and time in predicting primary PTSD and SUD outcomes across both treatments. Results: Significant verbal immediate memory by time interactions were found for both PTSD symptoms (p = .01, f (2) = 0.020) and percent heavy drinking or drug use days (p = .004, f (2) = 0.020). There was a significant working memory by time interaction for percent heavy drinking or drug use days (p = .007, f (2) = 0.016). Participants with better verbal memory had greater reductions across time in PTSD symptoms and drinking/drug use, while those with better working memory had lesser reductions in their drinking/drug use across time. Conclusions: Individuals with lower verbal memory functioning had less robust PTSD and SUD symptom reductions in PTSD/SUD psychotherapy, with differences that were generally small in magnitude. Those with better working memory functioning had worse SUD outcomes. Together with prior literature, findings suggest that neurocognitive functioning may impact the effectiveness of PTSD and SUD treatment. What is the public health significance of this article? This study suggests that psychotherapy for veterans with PTSD and substance use disorders may be less effective in individuals with lower verbal memory functioning.