Testing nature-based biopsychosocial resilience theory: a research programme protocol

Background
Interventions that use nature contact to promote health and well-being exist at the societal/infrastructural level (incl. nature-based solutions) and the individual/group level (incl. nature-based therapies). One way nature-based therapies promote health is by fostering resilience to manage stressors. Nature-based biopsychosocial resilience theory (NBRT) provides a framework to explain how nature plays a role in how resilience-related adaptive resources are built and maintained but this has yet to be tested.

Methods
The current paper outlines a four-year multi-country (Austria, Belgium, Bulgaria, Denmark, Italy, the Netherlands, Spain, Sweden, the UK) research programme that tests the NBRT framework and explores how nature-based therapies can build and maintain individual and community resilience. As well as reviewing and mapping existing interventions globally, nine case studies across Europe are exploring how nature promotes resilience across: (1) whole populations (three case studies); (2) individuals at-risk of metabolic syndrome (three case studies); and (3) individuals with existing issues such as chronic stress, mobility challenges, or cognitive impairments (three case studies). Three case studies use longitudinal cohorts, five use randomised controlled trials, and one a practitioner shared-experience approach. The determinants and impacts of nature-based therapies are also considered beyond effects on individual participants, by assessing distributional issues (e.g., health equity), environmental impacts, financial implications, broader societal acceptability and engagement, as well as the barriers and enablers to successful implementation. In three specific case studies (Barcelona, Padua and Salzburg), this is done through multi-sectoral social innovation actions we refer to as ‘Resilience Hubs’. Results will be summarised in academic publications, a series of sector-specific guides, and an overall ‘What works’ guide for practitioners, policy makers, and the public.

Discussion
We use a novel theoretical framework to structure a research and innovation programme to inform the implementation of nature-based therapies across Europe and globally. Challenges include the integration of terminology and research practices from multiple disciplinary perspectives, participant recruitment and attrition, especially among marginalised groups, a potential lack of local stakeholder time and interest, potentially small effect sizes of time-limited interventions, and difficulties in identifying distinct causal mechanisms. Mitigation strategies are discussed.

Trial registration
Of nine case studies (CSs), five are intervention trials and have been registered:
a) CS4 doi.org/10.1186/ISRCTN74582097 (22.07.2024);
b) CS5 doi.org/10.1186/ISRCTN14169596 (10.06.2024);
c) CS6 clinicaltrials.gov/study/NCT06622629 (30.09.2024);
d) CS7 doi.org/10.1186/ISRCTN93192592 (29.05.2024);
e) CS8 clinicaltrials.gov/study/NCT06205940 (15.05.2024).

All nine case studies have received ethical approval (see Declarations section).