CitationReynolds, Addam S. (2023). The Role of Social Contexts in Associations Between Early-Life Circumstances and Cognitive Aging: A Work Towards Aging Equity.
AbstractBackground: Alzheimer’s disease and related dementias (ADRD) are a public health priority in the United States due to the biopsychosocial ramifications of these disorders for individuals, families, and society. Facilitating and maintaining higher levels of cognitive performance throughout the life course may partially prevent ADRD. While most prevention efforts have historically focused on modifiable risk factors in middle and later life, scholars are increasingly identifying the early-life contextual factors that influence cognitive performance throughout adulthood. Largely absent from this literature are considerations of whether fundamental social contexts, such as racism and economic disadvantage, underlie these associations. This dissertation addresses this gap through three papers:
Paper 1: Early life adversity (ELA) refers to childhood experiences that would theoretically over-activate a stress response or overwhelm coping capacities. While research in human and animal models indicate that dysregulation of the stress response can influence brain structure and architecture, there has been mixed evidence that supports that early-life adversity (ELA) is associated with later life cognition. Specifically, some research studies suggest that neglect, abuse, maternal death, and cumulative exposure to ELA, among others, are associated with later life cognition, but these associations are not always replicated across studies. Comparatively understudied are considerations of whether the association between ELA and later life cognition is influenced by socioeconomic disadvantage and racism. Paper 1 addresses this gap by ascertaining if childhood socioeconomic status (cSES) and race jointly moderate associations between ELA and cognition using data from adults ages 51 and older in the Health and Retirement (HRS) study.
Paper 2: While there is evidence of the protective role of higher cSES on cognition, the theory of Minority Diminished Returns (MDR) suggests that this protective effect may be diminished among Black individuals. Using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), I evaluate if associations between cSES and cognition are jointly moderated by race and region of childhood residence among a cohort of adults ages 25-34.
Paper 3: While studies suggest that higher parental education, and more broadly cSES, is associated with higher cognitive performance in later life, few studies have explored if this protective effect is diminished among Black individuals. Using data from the HRS, the Midlife in the United States (MIDUS) Study, and the National Social Life, Health and Aging Project (NSHAP), I test if the protective effect of higher parental education is diminished among Black participants ages 50 and over, relative to their White counterparts. Results: In paper 1, I found that among White participants, greater exposure to ELA was associated with poorer later life cognition at baseline, but not rate of change over time, and higher cSES buffered this association; in comparison, among Black participants, ELA exposure was not associated with later life cognition at baseline or over time, regardless of level of cSES. In paper 2, I found evidence that race and region of childhood residence jointly moderated associations between cSES and working memory, but not delayed recall, among a sample of young adults. Specifically, I found that the protective effects of higher cSES was salient among White participants and Black participants from outside the South, but not for Black participants from the South. Finally, in paper 3, I found evidence that, among pooled samples across three population health studies, the protective effect of higher parental education was diminished among Black participants in terms of episodic memory and global cognition. Conclusions: Early life contextual factors and their associations with cognition throughout the life course do not always operate the same across populations. Specifically, targeting ELA, cSES, and parental education as population health me sures to promote later life cognitive performance may not be universal across populations, but, rather, are conditional on social positions and their intersections. Collectively, these papers provide a foundational body of evidence that suggests that early-life risk and protection for cognitive aging should be considered in conjunction with intersecting social positions. These papers provide additional evidence of the need to address anti-Black racism to facilitate healthier cognitive aging across the life course.