D-cycloserine for treatment of numbing and avoidance in chronic post traumatic stress disorder: A randomized, double blind, clinical trial

BACKGROUND: Posttraumatic stress disorder (PTSD) tends to follow a chronic and treatment resistant course. Avoidance and numbing are symptoms associated with chronicity and impaired life quality. As D-cycloserine (DCS) can facilitate extinction of conditioned fear, we aimed to investigate the efficacy and tolerability of DCS for the treatment of numbing and avoidance in chronic PTSD. MATERIALS AND METHODS: This was an 11-week, double-blind, cross-over trial conducted in 2012 and 2013, in out-patient University psychiatry clinics. The studied population was selected randomly among outpatients with chronic combat-related PTSD (based on DSM-IV-TR criteria for chronic PTSD), who were males over 18 and <65 years of age (n = 319). Seventy six eligible patients were randomly assigned to two groups. Patients entered a 1-week run-in period. The groups received either an add-on treatment of DCS (50 mg daily), or placebo (4-week). After a 2-week washout, the groups received cross-over treatments (4-week). Clinical, paraclinical assessments, and clinician administered PTSD scale (CAPS) were performed at baseline, and at the end of the 1(st), 5(th), and 11(th) week. Side-effects were also evaluated. The overall number of avoidance and numbing symptoms, symptom frequency, and symptom intensity were measured separately. RESULTS: Neither frequency nor number of symptoms was significantly influenced. However, DCS treatment demonstrates a significant decrease in intensity of avoidance/numbing symptoms, and improvement in function (mean [standard error] = −4.2 [1.5], P = 0.008). Side-effects were not statistically remarkable. CONCLUSION: D-cycloserine can help as an adjunctive treatment to alleviate numbing and avoidance in combat-related chronic PTSD.