Background Opportunities for social connection between generations have diminished over recent decades because of changes in the way that we live and work. Intergenerational programmes may have a role in re-establishing connections thereby reducing loneliness and exclusion, improving mental health and tackling important issues such as ageism. However commissioning decisions are complex due to the range of options available.

Methods We produced an evidence gap map which provides an overview of the volume, diversity and nature of evidence to improve understanding of the role of intergenerational activities in health and social care. We searched sixteen bibliographic databases for research of any design in September 2021. We also searched websites of relevant organisations. Eligible studies included older adults and children/young people where there was at least one skipped generation taking part in an intervention seeking to bring older and younger people together to achieve positive health, social or educational outcomes. We used the Depth of Intergenerational Engagement Scale as the framework for describing interventions; this scale places activities on a continuum, with points that correspond to different levels of intergenerational engagement, ranging from initiatives that provide no direct contact between age groups (Level 1) to those that promote intensive contact and ongoing opportunities for intimacy (Level 7). We used EPPI-Mapper software to create an interactive map of the evidence.

Results We included 500 research studies (27 systematic reviews, 238 quantitative comparative (of which 38 were randomised controlled trials), 232 qualitative, 103 observational and 82 mixed methods). Studies were conducted in 26 countries with the most frequent being the US (n=327), Canada (n=33), UK (n=28) and Australia (n=25). Just over half the studies (n=276/500) involved regular meetings between younger and older people over several months (Level 5 on the Depth of Intergenerational Engagement Scale); activities ranged from arts and crafts, reading and letter writing to environmental activities. Most commonly reported outcomes for children/younger people were attitudes towards older people, knowledge and attainment and intergenerational interactions. For older people they were mental wellbeing, agency, attitudes towards younger people and intergenerational interactions. Studies also reported economic outcomes (n=3 studies), adverse or unexpected outcomes (n=46 studies) and factors affecting implementation of interventions (n=180 studies). Many studies measured and reported outcomes for one generation only with the opposite generation being considered as being part of the intervention.

Conclusion The map provides an invaluable resource for those who commission, deliver and research services in this area.