Non‐familial intergenerational interventions and their impact on social and mental wellbeing of both younger and older people—A mapping review and evidence and gap map

Abstract Background Opportunities for social connection between generations in the UK have diminished over the last few decades because of changes in the way that we live and work. The decline in communal spaces such as libraries, youth clubs and community centres mean that there are fewer opportunities to meet and mix socially with other generations outside our own families. Increased working hours, improved technology, changes in family patterns, relationship breakdowns within families and migration are also believed to be contributory factors to generation segregation. There are many potential economic, social and political impacts of generations living separate and parallel lives, for example, higher health and social care costs, an undermining of trust between generations reduced social capital, a reliance on the media to form understanding of others’ viewpoints and higher levels of anxiety and loneliness. Intergenerational programmes and activities can take many forms and are delivered in many settings.  Evidence suggests that intergenerational activity can have a positive impact on participants, for example, in reducing loneliness and exclusion for both older people and children and young people, improving mental health, increasing mutual understanding and addressing important issues such as ageism, housing and care. There are currently no other EGMs that exist that address this type of intervention; however, it would complement existing EGMs addressing child welfare. Objectives To identify, appraise and bring together the evidence on the use of intergenerational practice, to answer the following specific research questions: What is the volume, nature and diversity of research on, and evaluation of, intergenerational practice and learning? What approaches have been used to deliver intergenerational activities and programmes that may be relevant to providing such services during and in the subsequent recovery from the COVID‐19 pandemic? What promising intergenerational activities and programmes have been developed and are being used but have not yet been subject to formal evaluation? Search Methods We searched MEDLINE (via OvidSp), EMBASE (via OvidSp), PsycINFO (via OvidSp), CINAHL (via EBSCOHost), Social Policy and Practice (via OvidSp), Health Management Information Consortium (via OvidSp), Ageline (via EBSCOhost), ASSIA (via ProQuest), Social Science Citations Index (via Web of Science), ERIC (via EBSCOhost), Community Care Inform Children, Research in Practice for Children, ChildData (via Social Policy and Practice), the Campbell Library, the Cochrane Database of Systematic Reviews and the CENTRAL database between 22 and 30 July 2021. We searched for additional grey literature via the Conference Proceedings Citation Index (via Web of Science) and ProQuest Dissertation & Theses Global and via relevant organisation websites, for example, Age UK, Age International, the Centre for Ageing Better, Barnado's, Children's Commission, UNICEF, Generations Working Together, the Intergenerational Foundation, Linking Generations and The Beth Johnson Foundation) and the Ottawa initiative called Older Adults and Students for Intergenerational support. Selection Criteria Any intervention that brings older and younger people together with the purpose of interacting to achieve positive health and/or social and/or educational outcomes from any study design including systematic reviews, randomised controlled studies, observational studies, surveys and qualitative studies are included. The titles and abstracts, and later full texts, of records identified by the search methods were screened against inclusion criteria by two independent reviewers. Data Collection and Analysis Data extraction was undertaken by one reviewer and checked by a second with any inconsistencies identified and resolved through discussion. The data extraction tool was developed on EPPI reviewer and was modified and tested through stakeholder and advisor consultation, and piloting of the process. The tool was informed by the research question and the structure of the map. We did not undertake quality appraisal of the included studies. Main Results Our searches identified 12,056 references, after screening 500 research articles were included in the evidence gap map conducted across 27 countries. We identified 26 systematic reviews, 236 quantitative comparative studies (of which 38 were randomised controlled trials), 227 were qualitative studies (or had a qualitative element), 105 were observational studies (or had elements of observational methods) and 82 used a mixed methods approach. The outcomes reported in the research cover mental health (n = 73), physical health (n = 62), attainment and knowledge (n = 165), agency (n = 174), mental wellbeing (n = 224), loneliness and social isolation (n = 54), attitudes towards the other generation (n = 283), intergenerational interactions (n = 196), peer interactions (n = 30) and health promotion (n = 23) and including mutual outcomes such as the impact on community (n = 37) and perceptions on the sense of community (n = 43). Gaps in the evidence that were identified include: research that reports on mutual, societal and community outcomes of intergenerational interventions; more research on interventions classified as levels 1–4 and level 7 on the Intergenerational Engagement Scale, mental health, loneliness, social isolation, peer interactions, physical health and health promotion outcomes in children and young people; health promotion in older people; outcomes centred on care giver wellbeing, mental health and attitudes; economic outcomes; process outcomes and adverse or unexpected outcomes. Authors’ Conclusions Whilst a substantional amount of research on intergenerational interventions has been identified in this EGM, as well as the gaps identified above, there is a need to explore promising interventions not yet formally evaluated. Research on this topic is gradually increasing, and systematic reviews will be important to determine how and why interventions are or are not beneficial. However, the primary research needs to build more cohesively so that the findings can be comparable and avoid research waste. The EGM presented here will nevertheless be a useful resource for decision‐makers allowing them to explore the evidence with regard to the different interventions that may be relevant to their population needs and the settings or resources available to them.

health promotion (n = 23) and including mutual outcomes such as the impact on community (n = 37) and perceptions on the sense of community (n = 43). Gaps in the evidence that were identified include: research that reports on mutual, societal and community outcomes of intergenerational interventions; more research on interventions classified as levels 1-4 and level 7 on the Intergenerational Engagement Scale, mental health, loneliness, social isolation, peer interactions, physical health and health promotion outcomes in children and young people; health promotion in older people; outcomes centred on care giver wellbeing, mental health and attitudes; economic outcomes; process outcomes and adverse or unexpected outcomes.
Authors' Conclusions: Whilst a substantional amount of research on intergenerational interventions has been identified in this EGM, as well as the gaps identified above, there is a need to explore promising interventions not yet formally evaluated. Research on this topic is gradually increasing, and systematic reviews will be important to determine how and why interventions are or are not beneficial.
However, the primary research needs to build more cohesively so that the findings can be comparable and avoid research waste. The EGM presented here will nevertheless be a useful resource for decision-makers allowing them to explore the evidence with regard to the different interventions that may be relevant to their population needs and the settings or resources available to them.
1 | PLAIN LANGUAGE SUMMARY 1.1 | Large evidence base for impact of intergenerational interventions involving young and old, but many gaps in research There is a considerable body of research evidence on intergenerational interventions and their impact on older people and children and young people. However, there are still many research gaps, and primary research could benefit from more consistency in outcome reporting.

| What is this evidence and gap map about?
Opportunities for social connection between generations in the UK have diminished over the last few decades because of changes in the way that we live and work. The Office for National Statistics Community Life Survey 2020-2021 reports that 6% of adults in the UK said they often or always felt lonely. People aged 16 to 24 were significantly more likely to report feeling lonely often or always, which is 11% of that age group. Nine percent of people aged 65 years and over reported the same.
Evidence suggests that intergenerational activity can have a positive impact on participants, for example, in reducing loneliness and exclusion for both older people and children and young people, improving mental health, increasing mutual understanding, and addressing important issues such as ageism, housing and care.
However, knowing what to implement, how and for whom is complex due to the lack of evidence about their effectiveness, transferability of effects across settings and cost-effectiveness. This evidence gap map (EGM) identifies the nature, volume and types of intergenerational interventions found in the research literature. It identifies areas for future research and evidence synthesis to help decision makers make more informed choices.

| What is the aim of this evidence and gap map (EGM)?
The aim of this EGM is to identify all the existing research evidence on intergenerational interventions to improve understanding about intergenerational activities in terms of the health and social care outcomes of older people, younger people and children, and to inform future research.

| What studies are included?
The EGM includes 500 research articles of any design on intergenerational interventions that do not include family members.
The evidence comes from 27 countries. CAMPBELL ET AL.

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We identified 26 systematic reviews, 236 quantitative comparative studies (of which 38 were randomised controlled trials), 227 qualitative studies (or had a qualitative element), 105 observational studies (or had elements of observational methods) and 82 with a mixed-methods approach.
1.5 | What are the main findings of this EGM?
The most commonly reported outcomes for children and young people were attitudes towards older people, knowledge and attainment, and intergenerational interactions.
For older people the most commonly reported outcomes were mental wellbeing, agency, attitudes towards younger people, and intergenerational interactions.
We identified several gaps in the research, including research on mutual, societal and community outcomes, young people's mental health, loneliness, social isolation, peer interactions, physical health and health promotion, outcomes centred on caregiver wellbeing, mental health and attitudes, and adverse or unexpected outcomes, including economic outcomes.
Interventions were most commonly delivered in schools, in the community or in care homes.
Interventions most commonly involved activities related to sharing perspectives of being an older or younger person/child, spending time together, helping with chores, helping more generally within a school environment, mentoring, art and crafts to engage the generations together, learning or sharing music and playing games.

| What do the findings of the map mean?
The EGM provides a starting point for researchers and decision makers to access the available research evidence on the effectiveness of intergenerational interventions.
The map demonstrates considerable diversity in the types of intergenerational activity. It also shows that it is mainly demonstration projects that are evaluated.
The quality of the evaluations makes analysis of their effectiveness, and hence their impact on shaping practice and policy, limited.
Methods of supporting useful evaluations of these types of interventionsso they are measuring meaningful outcomesis needed. This EGM identifies many areas where there are still gaps in research.

| How up-to-date is this EGM?
The authors searched for studies published up to July 2021.

| The problem, condition or issue
Opportunities for social connection between generations in the UK have diminished over the last few decades because of changes in the way that we live and work (Kingman, 2016; United for all Ages, 2017).
Housing and economic trends have seen younger people move to live in city centres whilst the older generation live in towns and rural areas.
A report published by the Intergenerational Foundation in 2016 (Kingman, 2016) suggests that in the 25 biggest cities within the UK only 5% of people aged over 65 live in the same neighbourhood as someone under the age of 18. Furthermore, even when people from different age groups do live in the same area, the decline in spaces such as libraries, youth clubs and community centres mean that there are fewer opportunities to meet and mix socially with other generations outside our own families. Increased working hours, improved technology, changes in family patterns, relationship breakdowns within families and migration are also believed to be contributory factors to generation segregation (Generations Working Together, 2019). There are many potential economic, social and political impacts of generations living separate and parallel lives, for example, higher health and social care costs, an undermining of trust between generations (Brown & Henkin, 2014;R. L. Jones, 2011;Laurence, 2016;Vitman et al., 2013); reduced social capital (Laurence, 2016); a reliance on the media to form understanding of others' viewpoints (Edström, 2018;Vasil & Wass, 1993) and higher levels of anxiety and loneliness. A review of the prevalence of loneliness in 113 countries found high levels of loneliness for a substantial proportion of the population in many countries (Surkalim et al., 2022). For example, in the Office for National Statistics Community Life Survey, 2020 to 2021 (ONS, 2021); 6% of adults in the UK reported feeling lonely often or always. Those aged 16-24 were also significantly more likely to report feeling lonely often or always (11% of that age group) with 9% of those aged 65 years and over report the same.

| The intervention
Intergenerational programmes and activities can take many forms and are delivered in many settings, very often by third sector organisations. Although evidence suggests that intergenerational activity can have a positive impact on participants (e.g., reducing loneliness and exclusion for both older people and children and young people, improving mental health, increasing mutual understanding and addressing important issues such as ageism, housing and care), commissioning decisions are complex due to the apparent wealth of options available, and yet limited and varying resources with which to provide them. This evidence gap map brings together all the available research evidence on intergenerational interventions.

| Why it is important to develop the EGM
Intergenerational programmes and activities are promising interventions that can address some of the needs of both children and young people and older people. The outcomes for children and young people and older people will form one of the key dimensions for the EGM-the list of which were developed from the frameworks listed below and through discussion with our stakeholder advisory group. The other dimension will be type of intergenerational intervention as categorised by the Depth of Intergenerational Engagement Scale (Kaplan, 2004). These two dimensions will give an overall picture of broad types of interventions and outcomes that have, and have not, been researched. Intergenerational interventions can take many forms and are delivered in diverse settings, therefore it will be important to be able to distinguish which aspects and characteristics of the interventions are supported by the evidence. We will therefore use the filter function in the EGM to identify the research design, intervention setting, age of the children/young people involved, the focus or activities involved, and any participant characteristics that have been targeted by an intervention.
Although evidence suggests that intergenerational activity can have a positive impact on participants, commissioning decisions are complex due to the lack of evidence about their effectiveness, transferability of effects across settings, and cost-effectiveness. This evidence and gap map (EGM) will identify the nature, volume and types of intergenerational interventions that have been undertaken and evaluated. It will identify areas for future research and evidence synthesis.
There are currently no other EGMs that exist that address this type of intervention; however, it would complement existing EGMs addressing child welfare.

| OBJECTIVES
We aim to use existing evidence to improve understanding about intergenerational activities in terms of the health and social care outcomes of older people, younger people and children.
Our objectives are to: Identify and bring together the evidence on the use of intergenerational practice, to answer the following specific research questions: • What is the volume, nature and diversity of research on, and evaluation of, intergenerational practice and learning?
• What approaches have been used to deliver intergenerational activities and programmes that may be relevant to providing such services during and in the subsequent recovery from the COVID-19 pandemic?
• What promising intergenerational activities and programmes have been developed and are being used but have not yet been subject to formal evaluation? 4 | METHODS

| EGM: Definition and purpose
EGMs are maps of a specific sector or subsector which typically includes both systematic reviews and primary studies. Produced using the same systematic approach as systematic reviews, EGMs usually show what evidence is there, not what the evidence says (White et al., 2018).
The EGM framework will inform the inclusion and exclusion criteria of the EGM. Here, we describe the population, intervention, comparison, outcomes (indicators) and study designs for the map.

| Framework development and scope
The aim of this EGM is to capture the broad range of evidence from systematic reviews and primary research that has investigated intergenerational practice.
The EGM will enable policymakers and practitioners in the field to take account of the research evidence in the commissioning and use of intergenerational practice in health and social care. It will also highlight opportunities for intergenerational activities and programmes during and in the subsequent recovery from the COVID-19 pandemic and direct the commissioning of appropriate research where there are evidence gaps.
The scope of the EGM is defined by a framework of interventions and outcomes presented as two dimensions: the rows include interventions with sub-categories, and the columns outcome domains. The framework was developed in consultation with our stakeholders who identified how the interventions could be helpfully defined using an existing framework which categorises interventions based on the level of engagement they promote Depth of Intergenerational Engagement Scale (Kaplan, 2004). We identified several outcomes that the research literature in this area already reports on, however we were aware that using the literature alone does not help us to identify outcomes that may be of interest but are not reported on. To address this issue, we asked our stakeholders to review the list of outcomes we had drawn from the literature and suggest additional outcomes that they felt were also of interest/ importance. All these outcomes were then captured in the framework for the map. For the benefit/ease of those using the map the outcomes were grouped into the following subsections, outcomes for children and young people, outcomes for older people, mutual outcomes, for example, community, outcomes for others, for example, carers, economic outcomes, process outcomes and adverse or unexpected outcomes, so that they could be expanded or collapsed depending on the preferences of the user.
Further attributes can be considered and used to filter the results, such as the research design of the included studies or characteristics of the included populations, for example, age of the younger people, any people with vulnerable or protected characteristics. Each cell shows studies which contain evidence on that CAMPBELL ET AL. | 5 of 22 combination of intervention and outcome. Study characteristics including, for example, study design, setting, intervention level and intervention activity/focus are coded, and the evidence can be filtered by these characteristics.

| Stakeholder engagement
The following individuals have contributed to the project through the We convened three virtual whole project meetings to include stakeholders and advisory group members (during Months 1 and 3), which assisted with understanding and presentation of the evidence in the EGM. We used break-out rooms and other methods of sharing ideas and suggestions such as a JamBoard and individual meetings to ensure that as many views and perspectives were captured as possible. We followed large meetings up with smaller meetings/ phone calls where necessary.
Between meetings we involved people through email, telephone and video conferencing, depending on the nature of the involvement and the preference of individuals.
During the stakeholder meeting in month one the stakeholder group informed the development of the framework, which helped to form the matrix for the EGM. Working in smaller groups, we encouraged participants to identify outcomes and types of intervention. This was used, along with the wider literature to inform the components of the framework.

| Conceptual framework
We developed a broad logic model to portray the general theory/ pathway expected in any intergenerational intervention ( Figure 1).
Our conceptual framework is informed by the following: the five essential elements of wellbeing described by Nazroo and colleagues adopted by the Institute for Public Policy Research (IPPR) (Nazroo et al., 2005); the seven outcomes outlined in the Department of Health Social Care Green Paper, Independence, Well-being and Choice (DOH, 2005)  These were then further considered and discussed with our stakeholders to identify the relevant outcomes of interest for one dimension of the framework. The other dimension of the framework was informed by the Depth of Intergenerational Engagement Scale (Kaplan, 2004) which gives a broad category on intervention based on the level of engagement it requires between the two generations. As intergenerational interventions are delivered using different formats and in diverse settings, it is important to be able to easily identify intervention characteristics such as research design, intervention setting, age of the children/ young people involved, the focus or activities involved and any participant characteristics that have been targeted by an intervention. We will use the filter function in the EGM to capture and present these and these are further detailed below.
We expect the interventions to cover both universal and targeted approaches, and whilst these definitions are not explicitly used as a filter in the map, targeted approaches will be identifiable by the filters used to describe particular characteristics of the populations involved in the intervention.

| Types of study design
We wanted to capture all the available evidence (not just intervention effectiveness) regarding intergenerational interventions for users to be able to use the EGM to identify any research they were interested in and where the gaps in evidence still lie. Therefore, all study designs including systematic reviews, randomised controlled studies, observational studies, surveys and qualitative studies are included. Due to the substantial amount of research literature found we did not include news items describing intergenerational activities and programmes even if they reported innovative interventions not otherwise represented within the evidence base (as in the protocol).

| Types of intervention/problem
We included any intervention that brings older and younger people together with the purpose of interacting to achieve positive health and/or social and/or educational outcomes. These include reminiscence programmes, buddy systems, storytelling, school-based interventions and arts-based interventions as well as others. We used the Depth of Intergenerational Engagement Scale (Kaplan, 2004) as the framework for the interventions. This is described below:

| The Depth of Intergenerational Engagement Scale
The Depth of Intergenerational Engagement Scale places programmes and 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 (point 1) to those that promote intensive contact and ongoing opportunities for intimacy (point 7). Examples of intergenerational initiatives fitting into each point on the scale are described.

Learning about other age groups
Participants learn about the lives of persons in other age groups, although there is no direct or indirect contact.
Example: 'Learning about Aging' programmes designed to teach youth about aspect(s) of the aging process.
2. Seeing the other age group at a distance These initiatives facilitate an indirect exchange between individuals of two or more age groups. Participants might exchange videos, write letters, or share artwork with each other, Five essential elements of wellbeing (Nazroo et al., 2005) Seven outcomes in the social care Green Paper, Independence, Well-being and Choice (DOH, 2005) Six domains identified in which actions are required for child and adolescent health and wellbeing (UNICEF & WHO, 2020)

Resilience
Improved health and emotional well-being Good health but never actually meet in person.
Example: A pen-pal programme in which youth in an afterschool club exchange letters with residents of a nursing home.

Meeting each other
Initiatives culminate in a meeting between the young participants and older adults, generally planned as a one-time experience.
Example: A class of students plan for and visit a local senior centre in which all engage in activities during a July 4th picnic.

Annual or periodic activities
Often tied to established community events or organisational celebrations, intergenerational activities occur on a regular basis.
Although infrequent, these activities might symbolise intergenerational and community unity and influence attitudes and openness towards additional or ongoing activities.
Examples: Intergenerational activities at a school on Grandparent's Day, an annual community dance in which youth and older adults are actively involved, and Christmas caroling at assisted-living homes.

Demonstration projects
Demonstration projects generally involve ongoing inter- Example: A YMCA facility houses a senior citizen centre. Older adults and youth participate in a variety of age-integrated activities.
Programmes fitting into all points on this continuum provide positive experiences for interacting with persons in other age groups.
However, if the aim is ambitious, such as changing attitudes about other age groups, building a sense of community, enhancing selfesteem, or establishing nurturing intimate relationships, it becomes important to focus on programmes that fit into Levels 4-7 on the scale. Programmes would take place over an extended period of time, would last anywhere from a few months to many years, and would provide extensive interaction opportunities (Kaplan, 2004).

| Types of population
Older adults and children and young people. No age boundary restrictions were applied but we sought studies that suggest at least one skipped generation between the older and younger participants.
Studies in which participants were related by family or marriage were excluded. Inclusion was not determined by prior age cut-offs but by the included studies own definition of 'older people' and 'young people'.

| Types of outcome measures
We included all reported outcomes. Outcomes did not form part of the criteria for including studies in the EGM since we are keen to explore all of the available evidence.

Types of settings
Any setting or context. No restrictions on language.

Status of studies
We included studies irrespective of their publication status and their electronic availability. We also aimed to include ongoing studies where it was feasible to ascertain when the study will be completed. The interactive EGM can also be used to explore the data using the filters presented below.

| Filters for presentation
In addition to the interventions and outcomes, the following filters have been coded: Characteristics of the participants that the intervention targets (this was an iterative list that also aimed to include characteristics included in Progress Plus (O'Neill et al., 2014) Progress plus: • Minority groups (in either generation based on race, ethnicity, culture, language, LGBTQ) • Low socioeconomic status (in either generation) • Unemployment (in either generation) • Educational needs (in either generation • Social isolation (in either generation) Other important characteristics (discussed with the Stakeholder advisory group): • Mental health difficulties (in either generation) • Physical health difficulties (in either generation) • Age category of the children/young people-0-5 years, 6-12 years, 12-18 years, 19-30 years.

| Excluded studies
Of the 794 reports assessed for eligibility, 303 reports were excluded. One-hundred and eighty-six reports were excluded as they were considered the wrong study type, for example, reports that did not detail their research methods, descriptions or summaries of interventions, or were personal reports/descriptions of an intervention; 47 were excluded because they included the wrong population, for example, where 'intergenerational' referred to a spread across F I G U R E 2 Prisma flow diagram.  were excluded because they did not report on participant outcomes; 16 were excluded as they were duplicate reports. All 303 excluded studies are listed in Supporting Information: Appendix 2.

| Studies awaiting classification (if applicable)
None identified.

| Synthesis of included studies
The interactive map can be found here.

| Intervention level
We used the Depth of Intergenerational Engagement Scale (Kaplan, 2004)  are not represented as they did not meet the eligibility criterion with regard to the generations having direct contact/interaction with each other.
In Table 1  Grade students share activities with older people to develop friendships (Aday et al., 1996).  where very young children (0-5years) have their nursery/kindergarten located within a care home setting (Doll & Bolender, 2010;Rosa Hernandez et al., 2020;Skropeta et al., 2014).  Of the 183 studies reporting on process outcomes, 155 reported on factors affecting the implementation of the intervention being studied. The factors reported are dependent on the type of intervention being offered but, for example, some studies found that it was necessary to carefully select the activities available for older people and very young children (0-5years) to engage with together so as to ensure the generations were able and willing to mix, others found they needed to make sure there was a choice of activities available, whilst others working with older young people (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) found that sometimes extra preparation was needed for those groups to feel confident or ready to engage with their older adult counterparts. Approximately 55 studies explored mechanisms underlying the intervention being studied. Elements such as valuing interactions that incorporate learning and insights in both generations (Lane, 2016); how promoting positive experiences was key to developing meaningful and satisfying relationships (Kamei et al., 2021); how characteristics of either generation can impact on success/engagement, and how success/engagement in these interventions can impact on the characteristics of both generations.

| Outcomes reported
Sustainability factors were explored by 46 studies, these factors overlap with factors affecting implementation but also look forward towards resolving challenges for future interventions. Very few studies explored managing risk within the intervention (n = 7), and of those that did, the concerns were related to the circumstances where young people shared accommodation with older people or where young children entered an older person's setting like a day care centre or care home.

| Risk of bias in included reviews
Risk of bias was not assessed as part of this EGM as per the protocol.

| Participant characteristics
We were able to identify studies that targeted specific participant characteristics, and these are described below.

Progress plus characteristics
Fifty-one studies targeted children and young people with vulnerable characteristics. Of these, 6 involved minority groups (institutionalised children, those affected by race or cultural differences), 13 involved children and young people from low socioeconomic backgrounds, 2 involved those experiencing social isolation, 11 involved children with educational needs and 5 involved young people who were unemployed. Eighty-eight studies targeted older people with vulnerable characteristics. Of these two involved minority groups (those affected by race or cultural differences), ten involved those from low socioeconomic backgrounds, five involved those experiencing social isolation and no interventions specifically involved older people who were unemployed. We did not identify any research that looked at other Progress Plus characteristics such as gender, LGBTQ, religion or place of residence.

| Setting
The intergenerational interventions identified in this EGM took place across at least 10 different settings described below (Table 3).
The descriptions in 25 studies were unclear where (which setting) the intervention was conducted in and where 'other' is reported in the setting (n = 28) 10 are systematic reviews covering more than one setting, eight are interventions that used digital interventions such that the true 'setting' may be mixed or unclear, seven are interventions that took place in mixed settings, and three are interventions that were conducted in a holiday/retreat type setting.
None of the studies were conducted in secure institutions.

| Intervention focus
Approximately 25 different intervention activities (or focuses) were recorded in this EGM (Table 4)

| Bibliometric analysis
In Figure 6 we can see there has been a steady increase in the number of studies evaluating intergenerational interventions pub- Hospital 7 Other 28 2020. This may reflect a growing trend in evaluating these types of interventions and publishing the results, or an increase in the number of intergenerational interventions ( Figure 6). RQ2-What approaches have been used to deliver intergenerational activities and programmes that may be relevant to providing such services during and in the subsequent recovery from the COVID-19 pandemic?
The interventions themselves report using at least one of 25 different activities as the focus for an intervention but in many occasions multiple activities are used Table 4. Some of these activities (n = 8) were conducted online which would enable these activities in particular to carry on amid a pandemic. Such activities included but were not limited to sharing learning or perspectives and gaming online or mentoring through videoconferencing or email, or letter writing. Some activities that can be conducted either online or in outside spaces may work for pandemic recovery periods such as gardening activities, physical exercise or leisure activities conducted outside, excursions or trips or environmental activities. Other activities that need direct in person contact through music, drama, arts and crafts might be more suited to non-pandemic times. and 7 in Kaplans Intergenerational Engagement Scale (Kaplan, 2004). This could be due to interventions in Levels  By nature of our inclusion criteria that specifies that 'Any intervention that seeks to bring older and younger people together to intentionally with the purpose of interacting', the EGM does not include interventions at level 1-2 where there is no direct contact between the generations. This does not mean that these types of interventions are unlikely to have an impact but they are not the focus of our research interest.

RQ3-
We did not conduct quality appraisal of the research studies identified. We deemed this an appropriate approach as we wanted the EGM to be as comprehensive as possible in capturing the research picture without being confusing for the viewer (quality appraisal of different study designs would have been difficult to present in the EGM without oversimplifying the appraisal, which would undermine the usefulness of the information). The subsequent reviews that involve the use of this research map and that focus on intervention effectiveness, should ensure that quality appraisal is undertaken before making recommendations with regard to policy and practice.
Whilst the design of our framework may have limitations (other approaches may have been possible)-the design of our framework was led by the stakeholders. We used a framework that they were familiar with and is used by major intergenerational organisationswe were keen to use a framework that made sense to the people who we hoped would use the map. The level of engagement in an intervention was also seen to be a key driver for successful interventions and is also an indicator of the potential resource level required for implementation which may be helpful for some users.
We felt that using the aims of an intervention would have been difficult to capture in the space of a map and would have been complex as interventions may have more than one aim. This might have made the map more difficult for users to access.

| Stakeholder engagement throughout the EGM process
We liaised with our stakeholders to confirm the details of the protocol before submitting this to Campbell. We were unable to meet with our stakeholders in person and conducted our first meeting online in one large group. At this meeting it was decided that subsequent meetings would be better conducted over two events within the same week to enable some flexibility in attendance and to ensure the meeting could be better facilitated for all attendees. At any point if any stakeholders could not attend the planned meetings they were given the opportunities to have one-to-one meetings with one of the project team or to share their thoughts and feedback over email. Stakeholders were also consulted about the structure of the EGM and how best to capture the outcomes they thought were important as well as the outcomes actively reported in the research. Two stakeholders have not engaged with the project so far but we hope to reconnect with them in the next stages. Details of the two meetings are in • A need to explore gaps in terms of promising interventions not yet formally evaluated.
• Further primary research needs to build on the evidence for existing interventions exploring a more consistent set of outcomes relevant to both generations engaged in the intervention. This should include the wider impact of the intervention on their families and/or carers and the wider community.
• More primary research is needed on mental health and the mental wellbeing of children and young people, and also loneliness and social isolation in both generations.
• Further primary research should also focus on issues with regard to intervention implementation and sustainability including economic outcomes so that policy makers and commissioners as well as service providers can make better informed decisions as to what intervention might work well and be sustainable for the community with which they are working.
• Further research needs to be conducted on Level 7 type interventions in which the interactions between the generations are built into the community and part of every-day communication, interaction and general living, with the potential thereby for demonstrating lasting positive impacts for everyone involved.
These interventions could potentially be more costly and therefore decision-makers need to be confident about the individual, social, economic and community benefits (as well as costs).
Implications for policy are: • Uncertain in many circumstances because much of the available research does not currently tell us what the impact of the interventions are on both generations (i.e., where there may be positive outcomes for one generation there is a need to be mindful of the outcomes experienced by the other generation). Research that explores the outcomes of an intervention for only one generation need to be further explored before being implemented.
• The research on this topic is gradually increasing, and systematic reviews will be important to determine how and why interventions are or are not beneficial. However, the primary research area needs to build more cohesively so that the findings can be comparable and avoid research waste.
• The EGM presented here will nevertheless be a useful resource for decision-makers allowing them to explore the evidence with regard to the different interventions that may be relevant to their population needs and the settings or resources available to them. Vaidya-Sheffield Children's NHS Foundation Trust; Sally Pearse-Sheffield University.

DECLARATIONS OF INTEREST
ERC, members of our advisory group and members of the Only Connect steering group are involved in the delivery of intergenerational activities and programmes.

PLANS FOR UPDATING THE EGM
Once completed the evidence gap map will be updated as resources permit.

DIFFERENCES BETWEEN PROTOCOL AND REVIEW
Due to the substantial amount of research literature found we did not include news items describing intergenerational activities and programmes if they reported innovative interventions not otherwise represented within the evidence base (as in the protocol). However, this will be conducted in the subsequent reviews directly related to this EGM.
Due to the amount of research literature found we limited our additional searches (forwards and backwards citation chasing) as follows: we carried out backward citation chasing on the included studies within identified systematic reviews specifically looking for RCTs and systematic reviews not already included in the EGM; we did not check the citations of older key papers (forward citation chasing); we identified one key journal the Journal of Intergenerational Relationships and hand-search the contents; we did not conduct the horizon scanning process (we will search Nexus for relevant international news articles about intergenerational practices and Google for relevant reports, blogs, news articles and links to other relevant organisations) mentioned in the protocol but expect to conduct that in subsequent reviews.
In addition to the filters mentioned in the protocol additional amendments were made to include the following: