Clonidine for post-traumatic stress disorder: a systematic review of the current evidence

Background: Clonidine is a centrally acting anti-adrenergic agent that may have applications in post-traumatic stress disorder (PTSD), particularly for sleep.Objective: In this systematic review, we aimed to summarize the effect of clonidine on sleep quality and duration, nightmares, and PTSD symptom severity in adults with PTSD.Method: PubMed (Medline), Embase, PsycINFO, CINAHL, and clinicaltrials.gov were searched up to April 2023. Studies on clonidine use in adult PTSD patients reporting data on the effect on sleep, nightmares, and PTSD symptoms were included. A narrative summary and a meta-analysis of the study findings are presented.Results: Ten reports, accounting for N = 569 patients with PTSD (145 on clonidine and 436 controls), were included in the final selection. There were four case reports, four observational studies, one non-blind clinical trial, and one crossover randomized controlled trial (RCT). Median clonidine dose was 0.15 mg/day (range: 0.1-0.5 mg/day). Median follow-up time was 31 days (range: 3 days to 19 months). The quality of the evidence was rated from very low to low. There was marked between-study heterogeneity and low power in the individual studies, but many reported improved sleep quality, nightmare reduction, and improvement of PTSD symptoms for patients treated with clonidine. Meta-analysis was only possible for two studies reporting the effect of clonidine on nightmares, and showed no difference from the comparator (i.e. prazosin or terazosin) (odds ratio: 1.16; 95% confidence interval: 0.66 to 2.05), potentially pointing towards non-inferiority between these medications.Conclusions: Future research, such as well-powered RCTs, is needed to identify the efficacy in the lower dose range and the most suitable treatment group, and to obtain good evidence on the effects of clonidine in the treatment of sleep disorders related to PTSD.