Psychological interventions for mental health in adults with multiple long-term conditions: A scoping review and evolution of the evidence base

BACKGROUND: Managing multiple long-term conditions (MLTCs) within individuals is a key global public health priority. Psychological interventions are effective in improving mental health outcomes in single-condition populations, yet the evidence for adults with MLTCs remains scarce. This scoping review aimed to map existing evidence on psychological interventions for people with MLTCs, highlight literature gaps and offer recommendations for future research, practice, and policy. METHODS: The pre-registered review follows Arksey & O'Malley's (2005) framework and is reported in line with the PRISMA-ScR guidelines. We searched six databases (PubMed, Embase, Scopus, Cochrane, PsycNET, Web of Science) up to January 2025, including reference screening and a grey literature search. After screening 124 full texts, 54 studies were included. Eligible studies evaluated any psychological intervention in adults with two or more long-term health conditions and included a validated psychological health outcome. RESULTS: Existing research primarily focusses on a handful of chronic conditions (diabetes, cardiovascular disease, chronic pain), often alongside comorbid depression. Cognitive-behavioural therapy (CBT) and behavioural activation (BA) are the most frequently evaluated interventions, generally demonstrating positive effects on mental health and acceptability to patients. The evidence base has progressed from early-stage development and feasibility studies to effectiveness trials, though economic evaluations and implementation research are still scarce. Notable gaps include limited research on transdiagnostic approaches, underserved populations and studies involving healthcare providers and carers. Most studies are concentrated in Western countries, highlighting a need for broader geographic representation, particularly in the global South. CONCLUSIONS: Psychological interventions such as CBT and BA show promise for individuals with MLTCs, but significant gaps remain. Future research should i) prioritise inclusive, transdiagnostic approaches to MLTC management, ii) expand geographic diversity, iii) use data-driven approaches to identify and intervene on common MLTC clusters and iv) incorporate health economic and implementation considerations to support more effective and equitable mental health care for those living with MLTCs.