Session-level effects of prolonged exposure therapy with and without topiramate in veterans with posttraumatic stress disorder and alcohol use disorder.

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) commonly co-occur and are associated with worse outcomes and treatment engagement than either disorder alone. Research and clinical practice guidelines support treating PTSD + AUD concurrently, with the combination of trauma-focused psychotherapy and pharmacotherapy demonstrating promise. Topiramate (TOP) can reduce AUD symptoms with emerging evidence that it may also attenuate PTSD symptoms. In a recent randomized controlled trial, veterans (N = 100) receiving prolonged exposure (PE) with TOP (PE + TOP) demonstrated greater reduction in PTSD at post-treatment than those randomized to PE with placebo (PE + PLA). However, it is unclear when in treatment symptoms begin to differ between the two conditions. This study examined the timing of treatment effects for PTSD and depression symptoms and alcohol cravings between conditions. Linear mixed effects models revealed that in the PE + TOP group, PTSD symptoms improved to a greater extent beginning at session 9 (b = -5.14, SE = 2.46, p = .04) and alcohol cravings to a greater extent beginning at session 6 (b = -3.10, SE = 1.33, p = .02) compared to PE + PLA. Depression symptoms did not differ by condition. Exploratory cross-lagged analyses disaggregating between- and within-person effects suggested that reductions in alcohol cravings during therapy may have driven subsequent session improvements in PTSD symptoms across conditions (b = .40, SE = .13, p = .003). TOP may enhance trauma-focused treatment, particularly once the maximum dose of medication is reached. Reductions in alcohol cravings during treatment may be an important mechanism of treatment progress.