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).