Evaluating seven nature-based therapy interventions to reduce stress in at-risk adults: protocol for a multicentre experimental study across four European countries (GreenME Project)
Open Access
- 10 September 2026
- journal article
- Published by CERN in Open Research Europe
Abstract
Background Mental health conditions are widespread over the society and stigma exacerbates mental health impact on the individual. Nature-based therapies (NBTs) show potential to improve mental health and could have a role in modifying the links between stigma and mental health, but robust evidence remains limited. This paper describes a multi-country experimental study protocol designed to evaluate whether diverse NBTs are superior to usual care in reducing stress among adults at risk of developing mental health conditions. Secondary objectives include examining superiority in improving quality of life and subjective wellbeing, the durability of effects, exploring whether NBT participation modifies the relationship between stigma and mental health, assessing cost-effectiveness, and investigating nature connectedness as a potential mechanism. Methods Seven interventions are included: two in Spain, two in the United Kingdom, two in Italy, and one in Sweden. Participants are adults experiencing moderate-to-high perceived stress. Participants are randomized to NBTs plus unrestricted usual care or unrestricted usual care alone. Interventions involve non-clinical activities with direct contact with nature (gardens, forests, or the ocean), typically lasting 120 minutes over 12 consecutive weeks and facilitated by trained practitioners. Usual care varies by context. Data is collected at screening, baseline, post-intervention, 1-month and 3-months follow-ups. Measures include stress – as the primary outcome-, quality of life and subjective wellbeing – as the secondary outcomes-, exposure to green care, nature connectedness, internalized stigma and covariates. Primary analyses will follow the intention-to-treat principle, with intervention-level analyses followed by individual-level meta-analyses. Secondary analyses will also examine mechanisms, effect modification, and cost-utility and cost-effectiveness analyses. Discussion This study will generate robust evidence on health effects and cost-effectiveness of NBTs. Findings can support scaling up NBTs effectively for mental health.Keywords
Funding Information
- UK Research and Innovation (10080427)
- European Commission (101084198)
This publication has 79 references indexed in Scilit:
- The Pittsburgh sleep quality index-2 (PSQI-2): the validity of a two-item sleep quality screener in Brazilian adultsSleep and Breathing, 2025
- Effects of Shinrin-Yoku (Forest Bathing) and Nature Therapy on Mental Health: a Systematic Review and Meta-analysisInternational Journal of Mental Health and Addiction, 2020
- A randomized-controlled trial of treatment for self-stigma among persons diagnosed with schizophrenia-spectrum disordersSocial Psychiatry and Psychiatric Epidemiology, 2019
- The effectiveness of narrative enhancement and cognitive therapy: a randomized controlled study of a self-stigma interventionSocial Psychiatry and Psychiatric Epidemiology, 2017
- Development and Validation of a Brief Version of the Difficulties in Emotion Regulation Scale: The DERS-16Journal of Psychopathology and Behavioral Assessment, 2015
- Review of the Psychometric Evidence of the Perceived Stress ScaleAsian Nursing Research, 2012
- Development and preliminary testing of the new five-level version of EQ-5D (EQ-5D-5L)Quality of Life Research, 2011
- A Brief Measure for Assessing Generalized Anxiety DisorderArchives of internal medicine (1960), 2006
- Inventory of complicated grief: A scale to measure maladaptive symptoms of lossPsychiatry Research, 1995
- The restorative benefits of nature: Toward an integrative frameworkJournal of Environmental Psychology, 1995