摘要：Opioids addiction and misuse are among the major problems in the world today. There have been several preliminary studies examining the effect of methadone on depression among addicts, however, these studies have reported inconsistent and even contradictory results. Therefore, the aim of the present study was to determine the effect of methadone on depression in addicts in Iran and around the world, using a meta-analysis approach. This study was a systematic review and meta-analysis including articles published in the SID, MagIran, IranMedex, IranDoc, Cochrane, Embase, ScienceDirect, Scopus, PubMed and Web of Science databases were searched systematically to find articles published from 2006 to March 2019. Heterogeneity index was determined using the Cochran's test (Qc) and I2. Considering heterogeneity of studies, the random effects model was used to estimate the standardized difference of mean score for depression. Subsequently, the level of depression reduction in Iran and worldwide in the intervention group before and after the testwas measured. A total of 19 articles met the inclusion criteria, and were therefore selected for this systematic review and meta-analysis. The sample size of the intervention group in the selected studies was 1948. According to the meta-analysis results, the mean depression score in the intervention group was 26.4 ± 5.6 and 18.4 ± 2.6 before and after intervention respectively, indicating the reducing effect of methadone on depression, and this difference was statistically significant (P < 0.01). The results of the present study show that methadone significantly reduces depression in addicts. Therefore, regular methadone use can be part of a drug treatment plan.
