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Introduction

In September 2023, the Committee on Population (CPOP) at the National Academies of Sciences, Engineering, and Medicine held a workshop, Developing an Agenda for Population Aging and Social Research in Low- and Middle-Income Countries (LMICs). The idea for the workshop grew out of conversations between CPOP and the National Institute on Aging (NIA), which led to the statement of task for the activity: see Box 1-1. The goal was to assemble a group of experts to discuss the research agenda on aging, with an emphasis on LMICs. The explicit goal of the workshop was to identify the most promising directions for behavioral and social research and data infrastructure investments for studying life-course health, aging, and Alzheimer’s disease and Alzheimer’s disease and related dementias (AD/ADRD) in LMICs.

The workshop was arranged around three broad themes: inequality, family change, and climate change. The workshop agenda is in Appendix A; biographical sketches of the interdisciplinary planning committee that convened to organize the workshop are in Appendix B.

BACKGROUND

The planning committee chair, Rebeca Wong (University of Texas Medical Branch), opened the first session by describing the interactive process with the National Academies and NIA that led to the workshop. The workshop goal was to identify priorities for future research and data collection in order to strengthen the evidence base for policy making.

Amy Kelley (NIA) shared the perspective of NIA, noting that the agency is the part of the National Institutes of Health that leads the federal government in conducting and supporting research on the health and well-being of older people. Among other topics, she said, NIA funds research to study aging in different social, cultural, and economic contexts in order to support the identification of behavioral, social risk, and protective factors that are associated with aging and life-course outcomes, including those related to AD/ARD. There has been less research in LMICs than in high-income countries, thus the workshop’s focus on LMICs. One challenge for research in this area, said Kelley, is that there is limited availability of representative longitudinal data; one goal of the workshop is to identify and discuss poten-

• the macro-social sources of worsening mental and physical health and mortality.

After this report’s release, Nielsen said, the COVID-19 pandemic and other global disruptions highlighted the fragility and the resilience of older populations around the globe, the interconnectedness of different societies, and the need to strengthen the collective search for innovative ways to meet the challenges and opportunities of global aging. She highlighted two recent publications that are the result of NIA’s partnership with CPOP: a consensus study on rising midlife mortality rates in the United States (National Academies, 2021) and a workshop summary on developing a research agenda on structural racism (National Academies, 2022). Nielsen said that she hoped that this workshop would help NIA formulate strategies for staying at the cutting edge of this work and building on the existing investments to develop high-value data infrastructure to meet the needs of the broader international aging research community.

Another NIA representative, Minki Chatterji, expanded on some of the projects that Nielsen and Kelley had mentioned. BSR, said Chatterji, engages the research community in order to help identify program priorities. For example, BSR is working toward achieving the implementation milestones for AD/ADRD that were recommended by the research community. BSR’s emphasis on global aging research addresses these types of community-identified priorities by examining how behavioral and social factors influence outcomes in varying social, cultural, and economic contexts. Chatterji explained that global and cross-national research can give clues about which policies or contexts lead to better outcomes, which can help people both in the United States and across the globe.

The HRS International Family of Studies are a major piece of this global research, said Chatterji.² These studies use nationally representative samples and follow participants over time with a multidisciplinary focus. While the studies are not identical across countries, they are harmonized in order to be comparable. The data from this research are publicly available, she said. While these studies have been conducted in over 40 countries, they have not yet included many LMICs. It is important to study LMICs, Chatterji explained, because some aspects of the social, cultural, and economic contexts are very different in LMICs than in the United States, and these differences can help illuminate what factors lead to different outcomes. For example, the differences between older adults in sub-Saharan Africa and those in the United States, which might lead to different outcomes, include more rural living, more time in multigenerational households and caring for younger people, staying in the labor force longer, living in countries with

Berkman noted that research on successful aging societies requires the collection of contextual-level variables that are often readily available; it does not necessarily require asking more of an “already-burdened set of participants.” In choosing countries for focused research, Berkman said that some countries are ripe for studying aging right now, while others should be prioritized for investments in future research. For example, she said, between 2025 and 2050, Mexico will undergo the transition from a younger population to an older one: see Figure 1-1. In prioritizing countries for research on the transition to an aging society, Berkman said that the focus should be on countries that are “on the runway” by 2050.

There are numerous social and physical determinants of health that can be studied in relation to aging, said Berkman. She shared data and findings from selected studies on several of these determinants. The first study she discussed looked at the effects of the amount of education on child health and adult mortality (Pradhan et al., 2017). It found that education of females had an “enormous” impact on mortality, particularly in low-income countries: see Figure 1-2. Specifically, the study showed that “14 percent of reductions in overall under-five mortality, 30 percent of reductions in adult female mortality, and 31 percent of reductions in adult male mortality can be attributed to gains in female schooling” (Pradhan et al., 2017, p. 427).

Another study used data from the Health and Aging in Africa: A Longitudinal Study in South Africa to look at the impact of multiple determinants—including education, employment, marital status, and health behaviors—on cognitive impairment (Kobayashi et al., 2021). This study found that education is “incredibly important,” as is literacy: see Figure 1-3, which shows those with education had the lowest relative incidence of cognitive impairment. These findings show the “lifelong impact of investing in education,” said Berkman.

Data from the Mexican Health and Aging Study have been used to look at how lifetime socioeconomic status (SES) affects trajectories of functional limitations and depressive symptoms in middle age: see Figures 1-4 and 1-5. Berkman said that these findings show that the effects of SES are “quite complicated,” and it can be challenging to tease out the separate effects of education, wealth, employment, and other factors.

Another important factor that has been studied as a determinant of health is adverse childhood experiences, said Berkman. A study from China found that each adverse experience contributes to an increasing risk of multimorbidity—the co-occurrence of two or more chronic conditions—(Lin et al., 2021): see Figure 1-6. She noted that there is a need to acknowledge the “huge number” of adverse events that people have experienced in many countries, including war, apartheid, famine, poverty, and disruption of family life and connections.

Berkman said that one of the most promising areas for future research is using natural experiments³ to look at the impact of policy on health outcomes. For example, a study in South Africa found that men who were newly eligible for pensions—due to lowering of the eligibility age—had higher than expected cognitive function (Jock et al., 2023). The study suggested cash transfers may hold promise as potential interventions to promote healthy cognitive aging.⁴ These types of policy “experiments” are a very powerful tool for learning more about the effects of interventions on health. In addition, she said, this type of research does not rely on people’s memory, which can be unreliable.

Another type of research that does not require asking people about their individual exposure is research on environmental conditions. For example, a study in China showed decreases in cognitive function with exposure to ambient particulate matter for middle-age and elderly Chinese

adults (Yao et al., 2022). It is essential, said Berkman, that researchers study the impact of the environment on aging health; climate change has huge consequences for people in LMICs, and it is critical to understand how policies could help or hurt these populations. She also noted that researchers looking at social determinants sometimes ignore the important role of health systems. A study in sub-Saharan African looked at how easier access to antihypertensive treatment could improve blood pressure control (Parati et al., 2023). It is essential, said Berkman, that researchers consider the role of multiple stakeholders—including governments, health care systems, the scientific community, development partners, communities, and individuals—when studying the factors that affect healthy aging.

In conclusion, Berkman encouraged researchers to identify demographic transitions in societies and to focus on major institutions that influence change, including educational, economic, political, environmental, and health systems. She emphasized the importance of using the perspective of an aging society rather than focusing on individual factors. However, she noted that societies are heterogeneous, and it is important to look both at averages as well as differences within populations. The distributional differences can sometimes “tell a more interesting story,” she said, and can expand knowledge about healthy aging for both individuals and populations as a whole.