(HealthDay News) — Prolonged exposure therapy administered as mass therapy is associated with a greater reduction in posttraumatic stress disorder (PTSD) symptom severity than a minimal-contact control (MCC), according to a study published in the Jan. 23/30 issue of the Journal of the American Medical Association.

Edna B Foa, PhD, from the University of Pennsylvania in Philadelphia, and colleagues conducted a randomized trial involving 370 military personnel with PTSD who had returned from Iraq, Afghanistan, or both. Participants were assigned to receive prolonged exposure therapy (cognitive behavior therapy involving exposure to trauma memories/reminders, administered as massed therapy [10 sessions over 2 weeks] or spaced therapy [10 sessions over 8 weeks]; 110 and 109 participants, respectively); present-centered therapy (PCT; non-trauma focused therapy involving identifying/discussing daily stressors; 107 participants); or MCC (telephone calls from therapists; 40 participants)

The researchers found that at 2 weeks after treatment, the mean PTSD Symptom Scale-Interview (PSS-I) score was 17.62 for massed therapy (mean decrease from baseline, 7.13) and 21.41 for MCC (mean decrease, 3.43; difference in decrease, 3.7; 95% confidence interval, 0.72 to 6.68). The mean PSS-I score was 18.03 for spaced therapy (decrease, 7.29; difference vs massed therapy, 0.79). At 12 weeks after treatment, the mean PSS-I score was 18.88 for massed therapy (decrease, 6.32) and 18.34 for spaced therapy (decrease, 6.97; difference, 0.55). The PSS-I scores for PCT were 18.65 (decrease, 7.31; difference in decrease vs spaced therapy, 0.1 [95% confidence interval, −2.48 to 2.27]) at post-treatment.

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“The reductions in PTSD symptom severity with all treatments were relatively modest, suggesting that further research is needed to determine the clinical importance of these findings,” the authors write.


  1. Foa EB, McLean CP, Zang Y, et al. 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. JAMA. 2018 Jan 23/30. doi:10.1001/jama.2017.21242