METHODS: 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.

METHOD: The electronic database such as Web of Science (WoS), Scopus, SID, PubMed, Google Scholar, Mag Iran, and IranDoc were systematically searched for studies reporting the prevalence of major depressive disorderin the elderly published up to March 2021. Meta-analysis was performed using Comprehensive Meta-Analysis (CMA) software. Heterogeneity between the studies was evaluated using the I2 index. Begg and Mazumdar rank correlation test was used to assess publication bias.

RESULT: A total of 20 studies involving 18953 participants were included in this study. The global prevalence of major depression in the elderly was 13.3 % (95 % CI: 8.4-20.3 %). In the subgroup analysis, the prevalence of major depression in elderly women was 11.9 % (95 % CI: 7.6-18.6) and men 9.7 % (95 % CI: 5.2-17.3). No comparison was made between the two sexes, but based on the confidence intervals and large overlap, the two groups are not statistically different. Among continents, Australia had the highest prevalence of major depression in the elderly at 20.1 % (CI: 14.5-27.2 %). This was followed by Europe at 12.9 % (95 % CI: 5.1-28.9 %).