Foa, E., McLean, C.P., Zang, Y., Rosenfield, D., Yadin, E… Peterson, A. (2018). Effect of prolonged exposure therapy delivered over 2 weeks vs 8 weeks vs present-centered therapy on PTSD symptom severity in military personnel: A randomized clinical trial. Journal of the American Medical Association, 319, 354-364.
Post-traumatic stress disorder (PTSD) can affect 10% to 20% of military personnel returning from combat. PTSD is often chronic and debilitating, and is associated with symptoms that are distressing, that lower quality of life, and that negatively impact family and loved ones. Prolonged exposure therapy (PE) has been tested in the past, and researchers have claimed that it is an efficacious treatment in civilians and veterans. PE is a form of behavior therapy and cognitive behavioral therapy characterized by re-experiencing the most traumatic event through remembering it and engaging with, rather than avoiding reminders of the trauma. In their treatment guidelines, the American Psychological Association (APA) proposed PE as a recommended treatment for PTSD. In this randomized controlled trial, Foa and colleagues assess if providing PE in intensive short time frame (massed exposure; 10 sessions over 2 weeks) was as effective as standard exposure (10 sessions over 8 weeks) for 370 military personnel in the US with PTSD. That is, the authors were interested to see if providing the same amount of therapy based on exposure in a shorter time was just as effective. They also compared the two versions of PE (massed and standard exposure) to two control conditions: present centred therapy (PCT) that is largely supportive therapy that does not rely on exposure to the trauma, and a no treatment control condition. The main outcomes were reductions in level of PTSD symptoms and reductions in PTSD diagnoses at post-treatment and up to 6 months post-treatment. Massed and standard PE were equally effective in reducing symptoms and diagnoses of PTSD compared to no treatment. However, PE was not more effective than PCT in reducing symptoms and diagnoses, and PCT was more effective than no treatment. Overall, reductions in PTSD symptoms and reduction in PTSD diagnoses were modest. Drop out rates were high at about 50% for all conditions.
Drop out rates were high and outcomes were modest for these short-term psychological treatments for PTSD in military personnel, such that over 60% still had a diagnosis of PTSD at 6 months follow up. And PE therapy did no better than a control condition (PCT) that simply provided support with no exposure to the trauma. These findings are similar to other research in this area. Psychotherapy for trauma may require more time to work, and perhaps different models of understanding and treating the disorder. As Shedler recently remarked, it takes at least 20 sessions/weeks before 50% of clients improve. So it may not be surprising that 2 or 8 weeks of therapy had only a small impact on PTSD symptoms.