Low-Dose Naltrexone (LDN) for Depression Relapse and Recurrence

We carried out a pilot double-blind, randomized, controlled study of low-dose naltrexone (LDN) 1 mg b.i.d. versus placebo augmentation in MDD patients who relapsed on dopaminergic agents. The primary aim was to test the hypothesis that patients experiencing depressive breakthrough would demonstrate greater improvement in their depression when supplementing their current antidepressant regimen with LDN versus placebo, with no significant difference in side effects. Boston area men and women with MDD were recruited from 01/13/2014-11/11/2014 via Institutional Review Board (IRB)-approved newspaper, television, internet, and radio ads initiated by Massachusetts General Hospital (MGH) and Boston Clinical Trials (BCT). Screened and eligible patients returned one week later for a baseline visit and were randomized consecutively to double-blind treatment with placebo or LDN 1 mg b.i.d. The randomization list was generated by an online randomization program and maintained by the research pharmacist. Subjects were treated for 3 weeks, with weekly assessments. All subjects were required to continue on their baseline antidepressant regimen without changes for the duration of the study; they were likewise asked not to modify any other allowed baseline medications that they had been taking prior to entering the study. Adherence was determined by weekly pill counts; protocol violation was defined as less than 80% adherence. Side effects were assessed at every visit using the Systematic Assessment for Treatment Emergent Effects-Specific Inquiry (SAFTEE-SI) scale (Levine and Schooler, 1992) and categorized by severity as: 0-none, 1-mild, 2-moderate, 3-severe. Because some SAFTEE items could be present at baseline, particularly in a sample of subjects taking antidepressants that could themselves produce side effects, we defined as treatment-emergent any SAFTEE side effect for which severity increased by two or more levels (e.g. from none to moderate or from mild to severe) from baseline (Mischoulon et al., 2014). Frequency of side effect was based on the number of patients reporting the side effect at any time during the study. Suicidal ideation was assessed at each visit using the Hamilton Depression Rating Scale (HAM-D). Subjects considered to be at high risk for suicide were discontinued and referred for further evaluation and hospitalization if clinically indicated. Subjects were also discontinued for any emergence of hypomania, mania, or psychosis; a Clinical Global Improvement (CGI-I) score greater than 5 (e.g., score of 6 or 7); evidence of illicit drug use or problematic alcohol use. At the end of the double-blind study, both responders and non-responders who completed the double-blind phase had the option of receiving open-label adjunctive treatment with LDN for 3 more weeks. Paired and independent samples t-tests and their nonparametric counterparts (Wilcoxon's signed ranks and Mann-Whitney U tests) were used to examine and compare outcomes for each treatment arm. All analyses were two-tailed. Response and remission rates, and emergence of side effects were compared by Fisher's exact test. Effect sizes (ES) were calculated by Cohen's d (Cohen, 1988), for between-subjects comparisons (changes in depression scales from baseline to end for LDN vs. placebo) and for within-subjects comparisons (changes in depression scales from baseline to end for each separate treatment group). Correlation coefficients were calculated for use in within-subjects comparisons. Statistical analyses were carried out using SPSS version 17.0 (SPSS Inc, Chicago, Illinois).