Essential oils as therapeutic and protective instruments in depression based on animal models: A systematic review and meta-analysis

Acting as complementary and alternative medicine tools, essential oils have been widely researched for depression due to their diverse potential therapeutic benefits and bioactive constituents in mood regulation. However, their efficacy and underlying mechanisms remain debated. This study aimed to analyze the efficacy of essential oils in alleviating depressive-like behaviors in animal models and to summarize the underlying mechanisms. We independently searched eight databases from their inception to May 2024 and eighteen studies satisfied the inclusion criteria. Considerable differences between the essential oils and control groups were found in sucrose preference test (SPT), forced swimming test (FST), and tail suspension test (TST), indicating promising potential for treating depressive-like behaviors. These findings suggest that essential oils can markedly alleviate depressive-like symptoms. Subgroup analyses revealed that animal strains, administration routes, and vehicle types were the primary sources of heterogeneity in the FST, with greater consistency observed in C57BL mice, intraperitoneal administration, and polar vehicles, respectively. However, a degree of publication bias was detected in SPT and TST. Finally, we also summarized the potential mechanisms underlying the antidepressant-like effects of essential oils reported in these studies. This study represents the first meta-analysis evaluating the antidepressant-like effects of essential oils in animal models. It provides valuable insights into the potential therapeutic and protective roles of essential oils for patients with depression in the future.