People with long-term mental health problems face profound social exclusion. They also die much younger than the general population from preventable causes. Despite a considerable body of research highlighting much higher rates of the main chronic and life-limiting diseases, later detection, and sub-optimal and fragmented care for people with severe mental illness (SMI), these inequalities appear stubbornly entrenched. Social exclusion for this population is characterised by an invisibility at policy and social levels and the challenges in meeting these complex needs with primary and secondary care services are immense. Using participatory approaches with stakeholders and experts by experience (stage 2), we identified the key challenges for implementation of social prescribing for people with SMI. These include: (1) diffusion of service responsibility and fragmentation of care; (2) limited (or absent) psychosocial support towards community engagement; (3) public and self-stigma leading to over-reliance on in-house (institutional) care; (4) policy confusion and neglect on SMI; (5) uneven distribution and ephemerality of community assets. Although social prescribing (SP) offers a potential solution by encouraging access to health-supporting amenities and resources and interagency collaboration, there is scant SP research for this population. The health and social care needs of this population require imaginative and nuanced models of health care that can accommodate their various and intersecting medical, social, and psychological needs while simultaneously influencing the environmental contexts in which they exist. The Challenging Health Outcomes/Integrating Care Environments (CHOICE) coalition has co-designed a delivery model which enhances interagency cooperation while providing more capacity at the community level to assess, appropriately prescribe, and provide flexible, sustained support to use a wide range of resources (assets, e.g., arts, leisure, and sports). In stage 3, Community Navigators based in our partner organisations will be trained in behaviour change techniques to encourage, guide and support people with SMI to use these resources. We will also extend the use of peer-support. This approach is intended to facilitate, incrementally, a virtuous cycle of improved self-esteem, self-efficacy, and social inclusion that enhances quality of life and wellbeing. Because research of this type has not been done before, our multi-disciplinary research team will undertake an adaptive mixed methods research programme to examine: (1) the outcomes of this approach; (2) the barriers and facilitators in implementing the CHIOCE model, such as the real-world issues of interagency cooperation and communication; (3) the needs and challenges of the voluntary and community partners; (4) the contextual and structural factors that might influence how the project works. Importantly, we will seek to gain a deeper understanding of CHOICE through our experts by experience who have a powerful and central role in the coalition and in the research process. Due to the embeddedness of all the key stakeholders in the CHOICE coalition, the findings will have a major impact on research, policy and practice in social prescribing, social inclusion, and health of people with SMI.

Over the coming decades the world will face a wide range of complex, new and persistent public mental health challenges, exacerbated by disruptive events, many of which can be fully addressed only through strategies and investments that improve lifelong public mental health outcomes for everyone. 1 in 6 adults in England have a common mental health condition. Mental distress and ill health are associated with significant disability, sickness absence, unemployment, and suicide attempts. Three quarters of all mental health conditions have occurred in young people by the age of 24 years. Despite widespread acknowledgement that mental distress and illness make a substantial contribution to the global burden of disease, there is still a major gap in evidence to inform policy making for their primary prevention. We will establish the 'Prevention of Risks and Onset of Mental Health problems through Interdisciplinary Stakeholder Engagement' (PROMISE) Population Mental Health Improvement Cluster, which will create new opportunities for population-based improvements in mental health. We will focus on three challenge areas: 1. Children and young people; 2. Suicide and self-harm prevention; 3. Multiple long-term conditions. Challenge areas will be supported by four cross-cutting themes: 1. Partners in policy, implementation and lived experience; 2. Data, linkages and causal inference; 3. Narrowing inequalities; 4. Training and capacity building. We will work with stakeholders across public health, local government, voluntary organisations and interdisciplinary academic experts, and people with lived experience of adversities which impact mental health, to identify and rigorously evaluate population-level interventions which hold the greatest promise for the improvement of mental health. The structure of our cluster reflects the integration of academic, policy and lived experience in leadership and delivery, which will lead to systems change and the ability to work effectively across traditional silos which have held progress in this area behind. We will use a range of large-scale datasets, including representative studies which follow people over time, nationally representative studies of health, and data generated when people come into contact with health and other services, take part in census, alongside information from children in schools, and the linkages between these, for our investigations. We will use statistical methods in this data to understand which population-interventions benefit people's mental health and reduce inequalities. We will draw on the wide-ranging interdisciplinary expertise of our team to develop a unique suite of training (seminars/ tutorials/ short training videos) which will be freely available, the training will be entitled "New ways of working in population mental health" and will cover a range of topics useful to researchers, practitioners, and people with lived experience. Our cluster will foster methods to develop creative and innovative solutions by working with people who have not applied their expertise to improving population health before, through a range of approaches:1. We will work with arts-based practitioners to develop creative outputs (films, children's books/ comic strips, animations, infographics, public photography and art exhibitions), which will also ensure inclusive engagement. 2. We will convene a series of interdisciplinary 'sandpit' events to engage a wide range of interdisciplinary groups, to develop innovative projects across challenge areas. 3. We will convene policy roundtables with support from English, Scottish, Welsh and Northern Ireland Government representatives, to bring together stakeholders, experts, policymakers, and the public to engage in discussion on cluster challenges to gather feedback, build consensus, and develop actionable recommendations. Our findings will be co-produced with people with lived experience.

In the UK and elsewhere, people with severe mental illness die prematurely, up to 20 years younger than the general population, a mortality often associated with modifiable medical risk factors. The substantial costs to the health system and the wider economy caused by smoking, obesity, physical inactivity, alcohol misuse and substance abuse are well established. For example, smoking rates among people with a mental illness are three times higher than among the general population. However, while smokers living with severe mental illnesses are just as likely to want to quit as the general population, they are generally more addicted, and face greater barriers to quitting. Similarly, weight gain and obesity are major problems for people with mental health problems, increasing the risk of developing diabetes or cardiovascular diseases, all contributing to low quality of life and exacerbating psychiatric symptoms. Other interwoven and modifiable risk factors associated with the poor physical health of people with mental health problems include low self-esteem, unemployment, loneliness, the low expectations of others, and social exclusion. For a range of social and psychological reasons, including the damage done by stigma, people with mental health problems have relatively limited access to local cultural and natural resources which could improve their physical and mental health. In recent years, greater attention has been focussed on the physical health of people living with mental illnesses but services remain fragmented and uncoordinated. This disconnect may be particularly true in the relationship between statutory health and social care services, and the community and voluntary sector organisations. Moreover, many lifestyle interventions exist that are of potential benefit to people with SMI these are seldom implemented in community settings and there is a lack of evidence on the development of effective interventions to help people with SMI. The CHOICE project aims to build a community coalition of agencies and people across Northern Ireland to maximise the resources, skills and knowledge held collectively. We will use Community-Based Participatory Research (CPBR), a powerful 'bottom-up' approach which uses innovative and inclusive approaches to empower disadvantaged communities and populations in the co- design and implementation of solutions to address health disparities. CBPR helps bridge research and practice by engaging the community to tackle disparities in population health and has been used in diverse and disadvantaged settings as an efficient means of challenging power imbalances. Importantly, our coalition will assist in identifying and exploiting all the assets and resources that exist in our communities but remain generally underused. Working with the experts by experience, we will use arts-based approaches to highlight the experience of living with mental illness, and the relationship between exclusion and physical health. By the end of the project we will have developed a strong community coalition and an agreed strategic plan to improve the lives of people living with mental illness.