Treatment of dissociative symptoms with opioid antagonists: a systematic review

BACKGROUND: The clinical guidelines for the treatment of dissociation focus primarily on psychotherapy. However, different psychoactive drugs are used in clinical practice. The use of opioid antagonists has been proposed as a therapeutic option based on the theory that dissociation might be a phenomenon mediated by dysregulation of the endogenous opioid system. OBJECTIVE: To review and meta-analyse the available evidence on the efficacy of the opioid antagonists naltrexone, naloxone, and nalmefene as treatments for dissociative symptoms and disorders. METHOD: The PRISMA guidelines were followed, and this review was registered in Prospero with reference number CRD42021280976. The search was performed in the PubMed, Scopus, Web of Science, EMBASE, PsycINFO, and PubPsych databases. RESULTS: 1,798 citations were obtained. After removing duplicates and applying inclusion and exclusion criteria, we included 5 comparative studies with 9 dissociation measures that had included a total of 154 participants, of whom 134 had been treated with an opioid antagonist. The results of the meta-analysis showed a treatment effect for dissociation when using opioid antagonists [pooled d = 1.46 (95% CI: 0.62–2.31)]. However, the studies we included were very heterogeneous [Q = 66.89 (p < .001)] and there may have been publication bias. CONCLUSIONS: Although more research is needed and the results must be interpreted with caution because of the limited amount of data and heterogeneity in the studies and their methodological qualities, opioid antagonists (particularly naltrexone) are promising candidates for the treatment of dissociative symptoms and showed a moderate – large effect size in reducing these symptoms.