Plant essential oils as a novel therapeutic strategy for depression and anxiety: emerging evidence and mechanisms

Depression and anxiety are major global mental health disorders that require safer and more accessible adjunctive interventions. This review uniquely integrates current evidence on plant essential oils in aromatherapy and identifies the cAMP–PKA–CREB pathway as a key mechanistic hub linking neurotransmitter regulation, HPA axis modulation, neuroinflammation, and neuroplasticity. Relevant animal, cell, and preliminary clinical studies were reviewed to summarize therapeutic effects, active constituents, and commonly used essential oils. The evidence indicates that essential oils may alleviate depression- and anxiety-like symptoms by increasing monoamine neurotransmitters, suppressing HPA axis hyperactivity, reducing pro-inflammatory cytokines, inhibiting NF-κB signaling, and restoring BDNF/CREB-related neuroplasticity. Representative active constituents include linalool, β-caryophyllene, and limonene, while lavender, bergamot, and chamomile are the most commonly studied essential oils. Overall, aromatherapy shows promise as a relatively safe and practical non-pharmacological adjunct for depression and anxiety, but its evidence base remains largely preclinical. More rigorous clinical studies are needed to confirm efficacy, standardize interventions, and clarify mechanisms in humans.