Topiramate as a therapy for chronic posttraumatic stress disorder.

Since the original publication of open-label suggestions of efficacy of adjunctive and monotherapy topiramate as a novel therapy for chronic posttraumatic stress disorder, three small, double-blind, placebo-controlled clinical trials conducted as pilot trials have been made public. The results of these studies, including efficacy, termination rates, and adverse effects resulting in termination are reviewed critically, including methodological limitations to interpretation of the findings. One study finds separation from placebo over 12 weeks for a reduction in total CAPS scores with a large effect size (d=1.63); a second finds significant benefit for re-experiencing but not total CAPS scores; and a third finds numerical superiority for topiramate but no significant benefit for any score reduction. Several problems, including unexpectedly high dropout rates in one study, limit the generalizability of these findings, but overall there is a signal of potential efficacy that warrants more adequately powered future clinical trials.