Correlates of Nonimprovement to Pharmacotherapy for Chronic, Antidepressant-Resistant, Military Service–Related Posttraumatic Stress Disorder: Insights From the Veterans Affairs Cooperative Study No. 504

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Posttraumatic stress disorder (PTSD) is a chronic and often difficult-to-treat condition that is prevalent among military veterans. First-line pharmacotherapy for this population typically involves antidepressants; however, veterans who do not improve are sometimes prescribed antipsychotics such as risperidone. A 2011 randomized controlled trial of adjunctive risperidone versus placebo for veterans with chronic, antidepressant-resistant, military service–related PTSD revealed no difference between groups. Hence, there is a need to examine predictors of nonimprovement for chronic, treatment-resistant PTSD.


We examined correlates of nonimprovement and delayed improvement (ie, ≥12 weeks) using data from 267 veterans with chronic, antidepressant-resistant PTSD who were prescribed adjunctive risperidone or a placebo. Veterans received 1 to 4 mg adjunctive risperidone (n = 133; mean dose, 2.74 mg) or a placebo daily (n = 134) in addition to their original treatment regimen over the 24-week trial.


Greater severity of PTSD symptoms at baseline, specifically reexperiencing (ie, nightmares) and emotional numbing (ie, sense of foreshortened future), was independently associated with nonimprovement. Of the 194 veterans (72.7%) who did improve, 95 (49.0%) showed delayed improvement, taking 12 weeks or longer to demonstrate a 10-point reduction in Clinician-Administered PTSD Scale scores. Emotional difficulties affecting role functioning, as assessed using the Veterans RAND 36-item Health Survey, independently predicted nonimprovement.


While results are indicative of nonspecific pharmacotherapeutic effects, they suggest that specific PTSD symptom clusters and impairment are associated with variable improvement in veterans with antidepressant-resistant PTSD. They underscore the importance of developing more effective and targeted pharmacotherapies for specific symptom clusters in this population.

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