RECETAS (Re-imagining Environments for Connection and Engagement: Testing Actions for Social Prescribing in Natural Spaces) is an European project (H2020 No 945095) that aims to reduce loneliness by linking lonely people to nature-based social activities through a group-based intervention.

Background: Loneliness is the perception of feeling alone, even if surrounded by people. Nature-based experiences can facilitate dynamic processes of social interactions and it can reduce feelings of loneliness. RECETAS aims 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.

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 of a 10-week NBSI on loneliness in vulnerable people in the area of Barcelona suffering from it compared to usual social and health care at post-intervention, and at 6-, and 12-months post-randomization. We will also explore the processes and perceived impacts of the intervention.

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 is a randomized controlled trial (RCT) including a process evaluation based on Medical Health Council guidance, a nested qualitative study and a Health Economics evaluation.

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 after the baseline assessment: NBSI treatment and control arms. All of them will be asked to sign the informed consent form.

The intervention model is adapted from the "Circle of Friends" methodology developed by the University of Helsinki (Jansson A, Pitkälä KH, 2021).

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.

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.