1

Introduction

Cognitive decline or impairment is a normal part of aging. It consists of some memory loss without affecting a person’s ability to perform everyday tasks. When the ability to perform everyday tasks is compromised, then an individual is diagnosed as having dementia, of which there are several types. The risk of cognitive decline does not increase uniformly with age. For example, memory performance at early ages in the United States is lower for Black people than for White people, even after adjusting for education. This performance remains lower though the distance between population performance for these groups decreases as both groups age (Figure 1-1 shows trajectories for episodic memory performance). Rates of dementia are higher among disadvantaged populations, with the implication being that social and institutional factors may affect the risk of dementia.

Alzheimer’s Disease (AD) is the most common type of dementia, but there are a variety of other diseases and injuries that affect the brain (World Health Organization, 2023). The predictors and policy implications may vary depending on whether one is talking about cognitive decline or dementia, and also across different types of dementias.

The National Institute on Aging (NIA) asked the Committee on Population within the National Academies of Sciences, Engineering, and Medicine (National Academies) to convene a workshop of experts to examine what is currently known about how midlife experience may affect the linkages between early life disadvantage and the state of cognitive health later in life. The stated goal of this work was to help set a research agenda and assess the prospects of identifying policy solutions to lower the risk (see Box 1-1 for the workshop’s statement of task). The Committee on Population selected

a committee of six experts (listed in Appendix B) who were charged with designing an agenda for a workshop and selecting and inviting appropriate experts to speak on the topic. The agenda developed by the committee included sessions to examine current patterns of dementia; investigate predictors and influences of dementia rates across the life course; and investigate key social factors that may influence dementia rates, such as education and the workplace, social and health policies, social support and integration, and environmental and cardiovascular exposures (see Appendix A for the complete workshop agenda). The committee then invited 15 experts from relevant fields to participate in a workshop and discuss the current state of the research and the research needs (see Appendix C).

The workshop was held in Washington, DC, on August 29 and 30, 2024. This proceedings provides a summary of what the speakers presented and the dialogue that followed. As this was a workshop, no attempt was made to develop a set of recommendations coming from the committee as a whole; rather, all conclusions and recommendations in this proceedings can be attributed only to the individuals who spoke, and none should be interpreted as presenting the opinions of the committee, National Academies, or NIA.

Malay Majmundar, director of the Committee on Population, welcomed participants to the workshop and described the role of the committee in developing the event, the motivation behind the work, and the planned products from the workshop.

Emerald Nguyen, program official at NIA, provided background information on why the workshop was requested. NIA’s mission is to understand the nature of aging processes, as well as the diseases and conditions associated with growing older. Nguyen emphasized that we all age from the moment we are born, so aging does not only concern the aged. For that reason, NIA takes a life course approach to aging, seeking to understand the aging process in health outcomes in midlife and later life.

NIA makes a variety of databases available to support research at no cost to investigators: these include data from the National Longitudinal Study of Adolescent to Adult Health (Add Health); Add Health Parent Study; Health and Retirement Study (HRS); Great Smoky Mountain Study of Rural Aging; Understanding America Study; High School and Beyond; Midlife in the United States (MIDUS); the National Social Life Health and Aging Project; Project Talent; and the Panel Study of Income Dynamics.¹ Many allow for linkages to administrative data and cross-national comparisons.

This particular workshop is funded by NIA’s Division of Behavioral and Social Research. Nguyen described NIA’s behavioral and social research priorities as inclusive of the following:

1. Studying aging early in the life course to identify mechanisms that affect aging processes and to promote prevention;
2. Enhancing research on cognitive aging, including normal cognitive aging and ADRD;
3. Improving the understanding of health disparities in aging;
4. Understanding the macro-social factors that shape health outcomes;
5. Supporting research on behavior change in individuals and organizations;
6. Supporting research to improve care for persons with dementia and their caregivers; and
7. Reducing barriers to accessing research data.

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¹ For information about the studies, see https://www.nia.nih.gov/research/dbsr/data-resources-behavioral-and-social-research-aging. For NIA’s depositories, see https://www.nia.nih.gov/research/resource/national-archive-computerized-data-aging-nacda, https://www.nia.nih.gov/research/resource/gateway-global-aging-data, and https://www.nia.nih.gov/research/dbsr/nia-data-linkage-program-linkage

NIA’s goal for the workshop was to identify research gaps and opportunities to accelerate knowledge concerning what pathways link early life disadvantage to later life cognitive health, including identifying key modifiable midlife exposures, high-priority measures, data infrastructure needs, and analytic approaches.

The workshop planning committee chair, Robert Hummer, Howard W. Odum Distinguished Professor of Sociology and Fellow of the Carolina Population Center at the University of North Carolina at Chapel Hill, named two key purposes of the workshop: (a) to learn how modifiable midlife social, structural, and institutional exposures link early life disadvantage to later life cognitive health and dementia risk; and (b) to take a life course perspective rather than a narrower moment-in-time perspective.

ORGANIZATION OF THE PROCEEDINGS

Chapter 2 presents the foundation for the workshop, discussing the extent to which early life disadvantages are expressed in the likelihood of cognitive decline at later ages. It also discusses how cognition changes across the life course and how midlife exposures may alter the dementia risk associated with earlier life factors. Chapter 3 presents modeling tools for combining datasets spanning separate life course periods, with the intention of viewing the entire life course and the pathways by which cognitive capacities may change. Chapters 4 through 7 examine different types of midlife exposures that might affect cognitive decline, including the evidence for such relationships and the methodological issues encountered when studying such relationships. Chapter 4 is focused on education and the workplace, two potential sources of stimulation where cognitive pathways can be built or maintained. Chapter 5 looks at how social and health policies may impact people with cognitive decline. Chapter 6 focuses on geographic neighborhoods as a factor affecting cognitive decline. Chapter 7 examines environmental exposures, such as lead in paint or in the air and other pollution, and their impact on cognition, along with cardiovascular exposures and their impact. Chapter 8 provides a summary, giving key takeaways from the workshop.

This proceedings follows the general structure of the workshop as a factual summary of what occurred at the workshop. However, some material has been reorganized to place related concepts together (in particular, placing much of the discussion that appeared at the end of each session in the context of the original presentation).

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