The essential elements for successful implementation of nature therapy programs in mental health services: A systematic review with narrative synthesis

Background: The potential of nature-based interventions (NBIs) for improving mental health is gaining interest worldwide. However, the elements for successful implementation of nature therapy programs by mental health service providers have not been clearly identified. The review question was, what elements are essential to successfully implement nature therapy programs in mental health services? Methods: The study was carried out as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Four electronic databases including Scopus, Web of Science, PubMed, and PsycINFO were searched to identify eligible studies. Studies were assessed for eligibility based on predefined inclusion criteria, and data were extracted in line with the review questions. Two reviewers independently used the Mixed Methods Appraisal Tool (MMAT) to assess the quality of the articles. Results: Out of 1663 articles, 38 met the inclusion criteria, with 9 found to have a high or moderate risk of bias. Sample sizes ranged from 8-781. The findings revealed that structured programs, guidance from trained multidisciplinary practitioners, and opportunities for participants to connect socially are key elements of successful implementation of nature-based therapy programs. Challenges to implementation were identified as logistical constraints, unfavourable external conditions, insufficient guidelines, and limited availability of resources. Conclusion: This systematic review highlights some components of successful implementation of nature-based therapy programs. However, implementation strategies are rarely reported. Subsequently evidence-based implementation advice for mental health services is limited. Registration: The protocol of this review was registered in the Prospective Register of Systematic Reviews (PROSPERO), under the identification number CRD42024562262.