Psychiatric conditions require long-term maintenance, and people with mental illness are often involved in care provided by multiple service providers. At the same time, reports indicate that people with mental illness and comorbid physical health conditions often fail to get their needs met in current systems. For example, coordinated support within the mesosystem is rarely available, and mesosystem fragmentation often results in individual suffering as well as inefficient use of societal resources. Meanwhile, integrated services, where collaboration is important, have shown superior effectiveness compared with services and support delivered in parallel silos. This contradictory image needs further investigation, and there is a need for a better understanding of the dynamics and complexities of collaboration within the mesosystem.

This review aims to map the mesosystem for services and support for people with mental illnesses. The review will seek to answer questions such as who are the actors (formal and informal) in the mental health services and support mesosystem, and how are collaborations among actors organised and implemented? To synthesise qualitative, quantitative and mixed methods findings, it uses a systematic integrative methodology. Searches will be conducted in PubMed, PsycINFO, CINAHL and Web of Science between 17th June and 21st 2024. Data will be extracted and synthesised using Covidence software. Two blinded researchers will make determinations regarding the inclusion and exclusion of articles. The subsequent process of analysis will be jointly conducted by the whole research team. Preferred Reporting Items for Systematic Reviews and Meta-Analyses tools for quality assessments will be used.

Articles included in the review will be analysed through an ethical lens, making sure that ethical considerations have been made where applicable. The study will result in a scientific publication in a peer-reviewed journal.

The study is registered in PROSPERO, no CRD42024543891.