Psychological predictors of memory decline in a racially and ethnically diverse longitudinal sample of older adults in the United States

ObjectivesIn the United States, racial and ethnic disparities in memory dysfunction and Alzheimer disease are evident even after accounting for many risk factors. Psychological factors, such as psychological well‐being, perceived control, depressive symptoms, and negative affect, may influence memory dysfunction, and associations may differ by race and ethnicity. This study examined whether psychological factors are differentially associated with episodic memory trajectories across racial and ethnic groups in the United States.Methods/DesignThe National Health and Aging Trends Study (NHATS), is a US‐representative, longitudinal study of Medicare‐eligible adults 65+ years old. Analyses of 5 years of data, included a total of 9411 participants without dementia at baseline. Adjusting for relevant covariates, a linear mixed model estimated the associations between psychological predictors and a composite of immediate and delayed trials from a word list memory test.ResultsMore depressive symptoms (B = −0.02), lower psychological well‐being (B = 0.03), and lower perceived control (B = 0.05) were independently associated with lower initial memory. Depressive symptoms were associated with faster rate of memory decline (B = −0.01). Black (B = −0.34) and Hispanic (B = −0.28) participants evidenced lower initial memory level than whites, but only Hispanic (B = −0.04) participants evidenced faster memory decline than whites. There were no significant interactions between the psychological variables and race and ethnicity.ConclusionsResults extend previous studies showing racial and ethnic disparities in episodic memory trajectories, and the longitudinal effects of depressive symptoms on episodic memory in US samples. Epidemiological studies of cognitive aging should incorporate more psychological factors clarify cognitive decline and disparities.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153704/1/gps5236.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153704/2/gps5236_am.pd

Social network characteristics moderate associations between cortical thickness and cognitive functioning in older adults

BackgroundAlthough prior research suggests that brain health is associated with cognitive functioning in later life, the strength of brain‐cognition associations varies. Lifestyle factors may alter these associations by either increasing or decreasing the probability of exhibiting cognitive symptoms at any given level of brain pathology. One lifestyle factor that prior clinicopathologic research has found to influence the association between greater Alzheimer’s disease pathology and lower cognitive performance is an individual’s total social network size. However, little is known about distinct social relationship types (i.e., family vs. friends).MethodThe current cross‐sectional study used data from the Washington Heights‐Inwood Columbia Aging Project (WHICAP; n = 654, 63‐96 years old, 62.40% Female) to examine whether distinct social network characteristics moderate associations between cortical thickness in regions implicated in Alzheimer’s disease and cognitive performance. Initial linear regression models examined the effects of total social network size, cortical thickness and their interaction on global cognitive functioning and individual cognitive domains (memory, language, speed/executive functioning, visuospatial function). Subsequent models tested the effects of distinct social relationship types (i.e., spouse/partner, number of children, other relatives, friends).ResultAlthough there were no main effects of cortical thickness or individual social network components on cognition, there was an interaction between cortical thickness and the size of friend networks. Specifically, lower cortical thickness was associated with lower global cognition among individuals with smaller friend networks, but not individuals with larger friend networks. When broken down by individual cognitive domains, this pattern of results was most prominent for language and speed/executive functioning. Total social network size and family networks (spouse/partner, number of children or relatives) did not moderate associations between cortical thickness and cognition.ConclusionResults are consistent with a growing body of literature suggesting that maintaining more friendships may promote cognitive reserve in older adulthood. Longitudinal, intervention, and functional neuroimaging studies are needed to determine whether interacting with friends strengthens neural networks that can support cognitive performance in the context of poorer brain health.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/171604/1/alz052227.pd

Longitudinal associations between racial discrimination and brain aging among black older adults

BackgroundNon‐Hispanic Black older adults exhibit worse brain and cognitive health than non‐Hispanic Whites. Emerging research points to racially‐patterned social stress (e.g., discrimination) as a contributor to racial inequalities independent of socioeconomic and health status. While comparative studies show that non‐Hispanic Blacks face more discrimination than non‐Hispanic Whites, few studies focus exclusively on non‐Hispanic Black older adults in order to examine within‐group heterogeneity and clarify how the unique experiences of discrimination among Black older adults link to their brain aging.Method221 non‐Hispanic Black participants in the Washington Heights‐Inwood Columbia Aging Project completed psychosocial measures and structural magnetic resonance imaging (MRI). Experiences of discrimination were operationalized using the Everyday Discrimination and Major Experiences of Lifetime Discrimination scales. After reporting the frequency of discrimination, participants reported the attribution(s) of these experiences (e.g., race). Latent difference score models examined associations between discrimination and brain aging, operationalized as hippocampal and white matter hyperintensity (WMH) volumes measured over an average of four years. Initial models considered general discrimination (i.e., regardless of attribution), and subsequent models considered racial discrimination per sé. All models controlled for age, sex/gender, education, income, total intracranial volume, and length of follow‐up.ResultGeneral discrimination was not associated with brain aging. Lifetime racial discrimination was associated with lower initial hippocampal volume. Everyday racial discrimination was associated with faster accumulation of WMH over time.ConclusionThis longitudinal MRI study suggests that racial discrimination may be detrimental for brain aging among non‐Hispanic Black older adults, which could contribute to their disproportionate dementia burden. Disaggregating discrimination by attribution can clarify research on psychosocial contributors to racial inequalities in brain and cognitive aging, as racial discrimination appears to be particularly toxic. Future research should examine both distal (e.g., environmental exposures, life course opportunities) and proximal (e.g., physiological stress pathways, inflammation) mechanisms linking racial discrimination to worse brain aging, which may differ for institutional versus interpersonal forms of racism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/171563/1/alz051948.pd