Testing a Nature-based Social Intervention on Loneliness: the RECETAS-BCN Trial

RECETAS (Re-imagining Environments for Connection and Engagement: Testing Actions for Social Prescribing in Natural Spaces) is a project that addresses loneliness and the role of nature-based social prescription (NBSP) to reduce it. This project has received funding from the European Union's Horizon 2020 research and innovation under grant agreement No 945094. More information at: https://recetasproject.eu/

Background: Loneliness is the perception of feeling alone, even if surrounded by people. It is a growing public health concern due to its impact on morbidity and mortality, being as dangerous as smoking or obesity: it reduces people's lifespan, and it is associated with chronic diseases as well as mental health symptoms. In Europe, 30 million European adults frequently felt lonely. Social prescription is a non-medical community referral approach to connect individuals with community resources to support wellbeing. Nature-based experiences can facilitate dynamic processes of social interactions and it can reduce feelings of loneliness. We will design and test a nature-based social intervention (NBSI) that is group-based and includes access to nature as a main component. The testing will be conducted in six different cities: Barcelona, Helsinki, Prague, Marseille, Cuenca in Ecuador and Melbourne. If successful, this will provide an evidence-based approach for using social prescribing to address loneliness.

Justification: NBSI in urban areas can improve health and mental well-being and reduce loneliness. Investments in nature-based solutions and green infrastructure can be harnessed for health and wellbeing even in times of health emergencies (covid-19). NBSI offers a novel socio-environmental innovation to reduce loneliness by creating the social infrastructure needed to support social and community cohesion.

Hypothesis: NBSI in vulnerable people suffering from loneliness is more effective than usual social and health care on reducing loneliness at post-intervention (10 weeks), 6- and 12-months follow up.

Objectives: to assess the effectiveness and to explore the processes and perceived impacts of NBSI in vulnerable people suffering from loneliness in the area of Barcelona. The specific objective is to assess the effectiveness of a 10-week NBSI on loneliness in vulnerable people suffering from it compared to usual social and health care at post-intervention, and at 6-, and 12-months post-randomization.

A pilot study will be conducted (September-December 2022) before the RCT intervention (January 2023) with the aim to explore the feasibility and acceptability of the study procedures, including the primary and secondary outcome measures.

Methods: The study design corresponds to a randomized controlled trial (RCT). The RCT will include a process evaluation based on Medical Health Council guidance, a nested qualitative study and a Health Economics evaluation. Therefore, overall, the RCT will use a mixed-method approach collecting quantitative information to assess the main outcomes and qualitative methods to explore lived experiences of participants and professionals. ISGlobal coordinates the overall RECETAS project, UVIC-UCC leads the implementation of the RECETAS-BCN and is responsible for the intervention, assessments, process evaluation and qualitative study. FSIE-UAB is responsible for the recruitment and data analysis. The Public Health Agency of Catalonia is involved and provides support to RECETAS-BCN.

The recruitment will be coordinated and operationalized with Community Development Plans (CDP). Individuals will be recruited from primary care settings, third-sector organizations, community groups, and volunteer organisations who screen for loneliness. A total of 316 participants will be randomly allocated in two arms (158 each): NBSP intervention arm and control arm. All of them will be asked to sign the informed consent form.

Participants are randomly assigned to the intervention or control arm after the baseline assessment.

The intervention is a theory-informed, multicomponent, multi-level, behaviorally based complex intervention that requires a specific training to prepare professionals as facilitators. The intervention model is adapted from the "Circle of Friends" methodology developed by the University of Helsinki by Pitkälä KH et al. It consists in: a) individualized session with facilitators (one-to-one interview), b) group-based program (5-15 people) for 9 sessions, once a week, including nature-based activities in the area chosen by the participants. Control group participants will receive usual care, and a list of nature-based resources available in their area.

• Nature-based social intervention (NBSI), referred as Friends in Nature (FiN) (Behavioral), also known as Amistat a la natura, Amistad en la naturaleza, Friends in Nature: The nature-based social prescribing is a multicomponent complex intervention applied by health or social care professionals as facilitators after a specific training. It comprises: a psychosocial component and nature-based activities. The psychosocial component is adapted from the group dynamic of "Circle of Friends" methodology focused on loneliness (Jansson A, Pitkälä KH, 2021) adapted to the cultural context of Barcelona and the target population of adults living in urban socio-economic vulnerable areas. Nature-based activities are chosen by group participants through a co-created menu comprising all local resources in the area related to nature. Specifically, participants start with an individual one-to-one session and then they meet once a week for two hours 10 weeks. Each week, participants decide the nature-based activity they wish to conduct.
• Usual care + menu with nature-based activities (Behavioral): Social prescribing as existing in usual care plus a written menu with the list of nature-based activities in the area.

Primary outcomes

• De Jong Gierveld Loneliness Scale 11 item [Post-intervention (10 weeks)]: Loneliness
• 15D instrument of health-related quality of life - 15D (Sintonen) [Post-intervention (10 weeks)]: Health-related quality of life

Secondary outcomes

• De Jong Gierveld Loneliness Scale 11 item [Baseline (before intervention), 6- and 12-months follow up]: Loneliness
• 15D instrument of health-related quality of life - 15D (Sintonen) [Baseline (before intervention), 6- and 12-months follow up.]: Health-related quality of life
• Multidimensional scale of perceived social support (MSPSS) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Perceived Social Support
• Pain Brief Inventory [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Pain
• Perceived Stress Scale (PSS-10) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Stress
• EURO-QOL 5D-5L [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Quality of Life scale to assess cost-effectiveness
• ICEpop CAPability measure for Adults (ICECAP-A) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: self-report measure of capability wellbeing for adults
• Satisfaction with Life scale (SWLS) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Satisfaction with Life scale as part of Wellbeing scales
• Spanish Subjective Happiness Scale [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Subjective Happiness Scale as part of Wellbeing scales
• Spanish adaptation of the Flourishing Scale Spanish adaptation of the Flourishing Scale [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Flourishing Scale as part of Wellbeing scales
• Cantril Ladder [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Wellbeing assessment
• Use of health and social services Use of health and social services retrieved from registers [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Retrieved from electronic medical records and self reported
• Lubben Social Network Scale-6 [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Social interaction
• Club/association participation [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Social interaction
• Questions on distance social relations adapted from adhoc questions asked by K. Pitkala team (Helsinki) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Social interaction
• PHQ-9 Patient health questionnaire [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Affect/Depression
• General anxiety disorder (GADS - 7) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Anxiety
• SPANE: Scale of positive and negative experience [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Emotions
• The 6-item neighborhood attachment scale (NAS) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Neighborhood
• Neighborhood aesthetics [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Neighborhood
• Nature Connection Index (NCI) [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Nature dose
• The International Physical Activity Questionnaires (IPAQ). [Baseline (before intervention), Post-intervention (10 weeks), 6- and 12-months follow up]: Physical activity
• Intrinsic motivation Inventory (IMI) [During intervention (4 week) and Post-Intervention (10 weeks)]: Participants subjective experience related to a target activity
• Relatedness to Others in Physical Activity Scale (ROPAS) [During the intervention (4 week), Post-intervention (10 weeks), 6- and 12-months follow up.]: Social support

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

1. To be able to give informed consent in Catalan or Spanish and able to participate to the group dynamics and communicate in at least one of these languages.
2. Aged 18 or over;
3. Currently experiencing loneliness according to the screening question "'Do you suffer from loneliness?" answers "feels lonely 'sometimes, often or always'); can walk to the center independently; able to participate in a group dynamics;
4. Willing to undergo study measurements.

Exclusion Criteria:

1. Unable to go outdoors independently due to poor mobility or severe diseases;
2. Poor hearing or sight in case it prevents them to participate of the group dynamics and activities in the nature;
3. Mild, moderate or severe cognitive decline (test de Pfeiffer >2 fails);
4. Any mental health disorder that might interfere with the group dynamics;
5. Severe disease with poor prognosis < 6 months.

• Sachs AL, Maso-Aguado M, Bach A, Opacin N, Hill N, Cattaneo L, Coll-Planas L, Johnson K, Hidalgo L, Daher C, Litt J, Bekessy S. Developing a new tool to capture the nature dose to reduce loneliness and improve quality of life. MethodsX. 2024 Sep 19;13:102969. doi: 10.1016/j.mex.2024.102969. eCollection 2024 Dec. PMID 39385940
• Vert C, Litt JS, Gascon M, Roque M, Maso-Aguado M, Opacin N, Garcia G, Jansson A, Cattaneo L, Bartova A, Briones-Buixassa L, Carbo A, Rautiainen LJ, Hidalgo L, Sachs A, Domenech S, Blancafort-Alias S, Holmerova I, Pitkala KH, Coll-Planas L. Evaluating the feasibility of "Friends in Nature," a complex nature-based social intervention to address loneliness and quality of life in six cities worldwide. Pilot Feasibility Stud. 2024 Nov 30;10(1):146. doi: 10.1186/s40814-024-01575-4. PMID 39616375
• Coll-Planas L, Carbo-Cardena A, Jansson A, Dostalova V, Bartova A, Rautiainen L, Kolster A, Maso-Aguado M, Briones-Buixassa L, Blancafort-Alias S, Roque-Figuls M, Sachs AL, Casajuana C, Siebert U, Rochau U, Puntscher S, Holmerova I, Pitkala KH, Litt JS. Nature-based social interventions to address loneliness among vulnerable populations: a common study protocol for three related randomized controlled trials in Barcelona, Helsinki, and Prague within the RECETAS European project. BMC Public Health. 2024 Jan 13;24(1):172. doi: 10.1186/s12889-023-17547-x. PMID 38218784
• Litt, J. S., Coll-Planas, L., Sachs, A. L., Rochau, U., Jansson, A., Dostálová, V., … Pitkälä, K. H. (2024). Nature-based social interventions for people experiencing loneliness: the rationale and overview of the RECETAS project. Cities & Health, 8(3), 418-431. https://doi.org/10.1080/23748834.2023.2300207
• Jansson A, Pitkala KH. Editorial: Circle of Friends, an Encouraging Intervention for Alleviating Loneliness. J Nutr Health Aging. 2021;25(6):714-715. doi: 10.1007/s12603-021-1615-5. No abstract available. PMID 34179921
• Results publication: Coll-Planas L, Maso-Aguado M, Briones-Buixassa L, Morato A, Mendez S, Carbo A, Fuente-Vidal A, Olivella-Cirici M, Casajuana Kogel C, Bartova A, Cattaneo L, Jansson AH, Kolster A, Novotna B, Opacin N, Papon V, Puntscher S, Rautiainen LJ, Rochau U, Blancafort-Alias S, Daher C, Bekessy S, Acurio-Paez D, Garcia Velez GE, Holmerova I, Johnson K, Segura LG, Siebert U, Pitkala KH, Sanz S, Litt JS. Effectiveness of a nature-based social prescribing intervention on loneliness and health-related quality of life among vulnerable urban adults (RECETAS-BCN): an observer-blinded randomised controlled trial. Lancet Reg Health Eur. 2026 Aug 18;69:101821. doi: 10.1016/j.lanepe.2026.101821. eCollection 2026 Oct. PMID 42662493
• Results publication: Papon V, Puntscher S, Maso-Aguado M, Arvandi M, Jahn B, Jones M, Beardmore A, Olivella-Cirici M, Briones-Buixassa L, Coll-Planas L, Litt JS, Siebert U, Rochau U. Evaluating the social return on investment of nature-based social prescribing to alleviate loneliness: a randomized controlled trial in Barcelona. Front Public Health. 2026 May 25;14:1774155. doi: 10.3389/fpubh.2026.1774155. eCollection 2026. PMID 42267287
• Results publication: Papon V, Puntscher S, Arvandi M, Jahn B, Litt JS, Coll-Planas L, Maso-Aguado M, Pitkala KH, Laakkonen ML, Roitto HM, Holmerova I, Bartova A, Jones M, Drummond M, Siebert U, Rochau U. Protocol for the health economic evaluation of nature-based social prescribing against loneliness alongside the RECETAS trials. BMC Public Health. 2026 May 9;26(1):2001. doi: 10.1186/s12889-026-27698-2. PMID 42106778

• Jill S Litt, PhD, Principal investigator, Barcelona Institute for Global Health