Markowitz, J.C., Petkova, E., Neria, Y., Van Meter, P.E., Zhao, Y., … Marshall, R.D. (2015). Is exposure necessary? A randomized controlled trial of Interpersonal Psychotherapy for PTSD. American Journal of Psychiatry, 172, 1-11.
Post-traumatic stress disorder (PTSD) is a condition caused by experiencing or witnessing a terrifying event. Symptoms may include flashbacks, nightmares and severe anxiety, as well as uncontrollable thoughts about the event. PTSD has a lifetime prevalence of 6.8%, which makes it a highly prevalent disorder. The main technique of empirically validated psychological treatments for PTSD involve exposing patients to safe reminders of the trauma including memories, with the intent of extinguishing the fear responses. This is the basis of cognitive behavioural therapy (CBT) with prolonged exposure, which is a consensus treatment for PTSD. However, not all patients benefit from CBT with prolonged exposure, and such treatment may be too difficult for some patients and therapists to tolerate. Markowitz and colleagues argued that PTSD symptoms reflect interpersonal issues including interpersonal withdrawal, mistrust, and hypervigilence. Interpersonal psychotherapy (IPT) is a time-limited efficacious treatment for depression that was adapted for this study for non-exposure based non-CBT treatment of PTSD. IPT was modified so that the first half of treatment focused on recognizing, naming, and expressing feelings in non-trauma related interpersonal situations. The second half of treatment focused on common IPT themes such as role disputes and role transitions. The authors argued that IPT helps individuals with PTSD gain mastery over social interactions and mobilize social supports. The authors conducted a randomized controlled trial that had a sufficient sample size to test a hypothesis of “non-inferiority”, that is to adequately test if PTSD and exposure based CBT were equally effective. Both treatments were compared to a progressive muscle relaxation (PMR) control condition. In all, 110 participants with chronic PTSD were recruited and randomized to IPT, CBT, or PMR. Most patients reported trauma of 14 years duration from either sexual or physical abuse, and half had a current comorbid depression. All three interventions resulted in large significant reductions in PTSD symptoms. IPT (63%) and CBT (47%) were not significantly different in rates of response (i.e., in which response was defined as 30% improvement in a clinician administered PTSD scale), but IPT had a significantly higher response rate than PMR (38%). Patients with comorbid depression were more likely to drop out of CBT with prolonged exposure than IPT.
The results of the study suggest that IPT and CBT with exposure were equally effective in reducing symptoms of PTSD. It is important to keep in mind that this is one well-conducted trial that needs to be replicated by independent researchers in order to establish if the findings are truly reliable. Nevertheless, the findings contradict the widespread belief that patients with PTSD require exposure-based treatment in order to improve. IPT may be another option for the treatment of PTSD, especially for patients who cannot tolerate the prolonged exposure. Patients with comorbid depression may have the most difficulty tolerating prolonged exposure therapy, and so they may benefit from IPT as an alternative. IPT may help patients gain abilities in social interactions and social support, which may make it easier for them to spontaneously expose themselves to recollections of trauma.