Forest therapy as an intervention for depressive disorders: a review of the mechanisms and applications

Depressive disorders have gradually become a challenging public health issue worldwide, highlighting the need for accessible, non-pharmacological interventions. Forest therapy (or Shinrin-yoku) has emerged as a promising, low-cost, and sustainable approach. As a low-cost, low-risk, and sustainable environmental intervention, forest therapy harnesses nature's bioactive and psychological effects to activate the body's intrinsic healing mechanisms while averting medication costs and side effects. The field of forest therapy faces challenges, including unclear mechanisms, a lack of objective biomarkers, and fragmented clinical applications, with few stratified intervention protocols or standardized operating procedures. This review synthesizes evidence on the mechanisms and clinical applications of forest therapy for depressive disorders, summarizes biological mechanisms and social pathways, analyzes the pathways and mechanisms through which forest therapy, as an intervention, influences human health, and addresses current limitations, such as small sample sizes, and future directions, such as multicenter randomized controlled trials. Finally, this review proposed an integrated Mechanism Model of forest therapy as an adjunctive treatment for depressive disorders. Unlike previous studies, this review uniquely integrates forest environmental elements with core pathological targets to elucidate their interaction mechanisms. From a depressive disorders-centric perspective, this study calls for more clinical research and evidence-based design of therapeutic landscapes to support the integration of forest therapy into depressive disorder management.