Demands placed on informal caregivers can result in an increased likelihood of experiencing common mental health difficulties that may affect their ability to undertake the caring role. Currently, however, few evidence-based interventions have been specifically developed for informal caregivers and available interventions are difficult to access. The Improving Access to Psychological Therapies (IAPT) programme aims to improve access to evidence-based psychological therapies for all groups and may therefore present an opportunity to meet informal caregiver needs. Located within the MRC Complex Intervention Framework, a Phase II feasibility randomised controlled trial (RCT) examines key methodological, procedural and clinical uncertainties associated with running a definitive Phase III RCT of an adapted written cognitive behavioural therapy (CBT) self-help intervention for informal caregivers of stroke survivors. Recruitment was low despite different recruitment strategies being adopted, highlighting significant challenges moving towards a Phase III RCT until resolved. Difficulties with study recruitment may reflect wider challenges engaging informal caregivers in psychological interventions and may have implications for IAPT services seeking to improve access for this group. Further attempts to develop a successful recruitment protocol to progress to a Phase III RCT examining effectiveness of the adapted CBT self-help intervention should be encouraged. Key learning aims After reading this article, readers should be able to: (1) Consider key feasibility issues with regard to recruitment and attrition when running a randomised controlled trial of an adapted written cognitive behavioural therapy (CBT) self-help intervention for informal caregivers of stroke survivors. (2) Understand potential barriers experienced by an informal caregiving population to accessing psychological interventions. (3) Appreciate implications for clinical practice to enhance access to IAPT services and low-intensity CBT working with an informal caregiver population.

IntroductionDementia is a worldwide health concern with incident rates continuing to increase. While depression prevalence is high in people with dementia and psychological interventions such as cognitive behavioural therapy (CBT) are effective, access to psychological interventions remains limited. Reliance on traditional CBT for people with dementia and depression may present difficulties given it is a complex psychological approach, costly to deliver, and professional training time is lengthy. An alternative approach is behavioural activation (BA), a simpler psychological intervention for depression. The present study seeks to work with people with dementia, informal caregivers, community stakeholders, and healthcare professionals, to adapt a guided low-intensity BA intervention for people with dementia and depression, while maximising implementation potential within the Swedish healthcare context.Methods and analysisA mixed methods study using codesign, principles from participatory action research (PAR) and normalisation process theory to facilitate the cultural relevance, appropriateness and implementation potential of the intervention. The study will consist of four iterative PAR phases, using focus groups with healthcare professionals and community stakeholders, and semi-structured interviews with people with dementia and informal caregivers. A content analysis approach will be adopted to analyse the transcribed focus groups and semi-structured interviews recordings.Ethics and disseminationThe study will be conducted in accordance with the Declaration of Helsinki and data handled according to General Data Protection Regulation. Written informed consent will be obtained from all study participants. In accordance with the Swedish Health and Medical Services Act, capacity to consent will be examined by a member of the research team. Ethical approval has been obtained from the Swedish Ethical Review Authority (Dnr: 2020-05542 and Dnr: 2021-00925). Findings will be published in an open access peer-reviewed journal, presented at academic conferences, and disseminated among lay and healthcare professional audiences.