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Background: Evidence suggests that long-term exposure to air pollution may increase the risk of dementia and related cognitive outcomes. A major source of air pollution is automotive traffic, which is modifiable by technological and regulatory interventions., Objectives: We examined associations of four traffic-related air pollutants with rates of cognitive decline in a cohort of older adults., Methods: We analyzed data from the Chicago Health and Aging Project (CHAP), a longitudinal (1993-2012) community-based cohort study of older adults that included repeated assessments of participants' cognitive performance. Leveraging previously developed air pollution models, we predicted participant-level exposures to the tailpipe pollutants oxides of nitrogen ( NO X ) and nitrogen dioxide ( NO 2 ), plus the nontailpipe pollutants copper and zinc found in coarse particulate matter [PM with aerodynamic diameter 2.5 μ m to 10 μ m ( PM 2.5 - 10 , Cu ) and PM 2.5 - 10 , Zn , respectively], over the 3 y prior to each participant's baseline assessment. Using generalized estimating equations, we estimated covariate-adjusted associations of each pollutant with rates of cognitive decline. We probed the robustness of our results via several sensitivity analyses, including alterations to the length of the exposure assessment window and exploring the influence of pre- and post-baseline selection bias., Results: Using data from 6,061 participants, estimated associations of these pollutant exposures with cognitive decline were largely inconsistent with large adverse effects. For example, a standard deviation ( 5.8  ppb ) increment in NO X corresponded to a slightly slower rate of cognitive decline [e.g., mean difference in change in global score, 0.010 standard unit/5 y, 95% confidence interval (CI): -0 .016 , 0.036]. The results of most of our sensitivity analyses were in generally similar to those of our main analyses, but our prebaseline selection bias results suggest that our analytic results may have been influenced by differential survivorship into our study sample., Discussion: In this large prospective cohort study, we did not observe compelling evidence that long-term TRAP exposure is associated with cognitive decline. https://doi.org/10.1289/EHP14585.

Introduction: Exposure to noise might influence risk of Alzheimer's disease (AD) dementia., Methods: Participants of the Chicago Health and Aging Project (≥65 years) underwent triennial cognitive assessments. For the 5 years preceding each assessment, we estimated 5227 participants' residential level of noise from the community using a spatial prediction model, and estimated associations of noise level with prevalent mild cognitive impairment (MCI) and AD, cognitive performance, and rate of cognitive decline., Results: Among these participants, an increment of 10 A-weighted decibels (dBA) in noise corresponded to 36% and 29% higher odds of prevalent MCI (odds ratio [OR] = 1.36; 95% confidence interval [CI], 1.15 to 1.62) and AD (OR = 1.29, 95% CI, 1.08 to 1.55). Noise level was associated with worse global cognitive performance, principally in perceptual speed (-0.09 standard deviation per 10 dBA, 95% CI: -0.16 to -0.03), but not consistently associated with cognitive decline., Discussion: These results join emerging evidence suggesting that noise may influence late-life cognition and risk of dementia., (© 2020 the Alzheimer's Association.)

Background: Having a larger social network has been shown to have beneficial effects on health and survival in adults, but few studies have evaluated the role of network diversity, in addition to network size. We explore whether social network diversity is associated with mortality, cognition and physical function among older black and white adults., Methods: Data are obtained from the Chicago Health and Aging Project, a longitudinal, population-based study of adults aged 65 years and older at baseline. Using Cox proportional hazards regression, we estimate the hazard of mortality by network diversity (n=6497). The association between network diversity and cognition (n=6560) and physical function (n=6561) is determined using generalised estimating equations. Models were adjusted for age, gender, race, socioeconomic status, marital status and health-related variables., Results: In fully adjusted models, elderly with more diverse social networks had a lower risk of mortality (HR=0.93, p<0.01) compared with elderly with less diverse networks. Increased diversity in social networks was also associated with higher global cognitive function (coefficient=0.11, p<0.001) and higher physical function (coefficient=0.53, p<0.001)., Conclusions: Social networks are particularly important for older adults as they face the greatest threats to health and depend on network relationships, more than younger individuals, to meet their needs. Increasing diversity, and not just increasing size, of social networks may be essential for improving health and survival among older adults., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2018. No commercial re-use. See rights and permissions. Published by BMJ.)

We compared trajectories of terminal cognitive decline in older Black (n = 3372) and White (n = 1756) persons from a defined population who completed tests of episodic memory and perceptual speed at 3-year intervals for up to 18 years. During a mean of 9.9 years of observation, 1608 Black persons and 902 White persons died. Preterminal decline of episodic memory did not differ by race. Terminal episodic memory decline began earlier in Black persons (mean of 4.3 years before death) than in White persons (mean = 3.9 years) and progressed more slowly. By contrast, terminal decline of perceptual speed began earlier in White persons (mean = 5.0 years) than in Black persons (mean = 4.5 years). Rate of perceptual speed decline was more rapid in White persons than in Black persons in both the preterminal and terminal periods. The results indicate that terminal cognitive decline occurs in Black persons but suggest that the rate of cognitive decline during the terminal period is less rapid in Black persons than in White persons.

Objective: To characterize secular trends from 1993 to 2012 in cognitive performance using a cohort of older black and white U.S. adults, and compare trends by race., Method: Our data come from 8,906 participants of the Chicago Health and Aging Project (CHAP), a longitudinal, population-based cohort (age ≥ 67, 60% black). Participants underwent cognitive assessments in six 3-year study cycles from 1993 to 1996 through 2010 to 2012. We computed 3 measures of cognitive performance: global cognition, episodic memory, and perceptual speed., Results: Mean performance in terms of global cognitive score followed a secular pattern of modest decline over the 6 study cycles. The trend was most pronounced for perceptual speed. Mean scores among black participants were consistently lower than those for whites; these disparities in mean performance narrowed over time, especially on perceptual speed, but appeared to widen at the last cycle. Global scores among the upper quartile of performers rose slightly, but scores among the lowest quartile of performers dropped precipitously., Discussion: Between 1993 and 2012, secular trends in cognitive performance in this established cohort did not follow a clear pattern of improvement, contrasting with previous research. But patterns differed by cognitive domain, performance level, and race.

Background: US-based studies have reported that older blacks perform worse than older whites on cognitive tests and have higher risk of Alzheimer disease dementia (AD). It is unclear whether these findings reflect differences in cognitive decline., Methods: The Chicago Health and Aging Project followed individuals, 65+ years old (64% black, 36% white), for up to 18 years. Participants underwent triennial cognitive assessments; stratified randomized samples underwent assessments for AD. We compared black and white participants' cognitive performance, cognitive decline rate (N = 7,735), and AD incidence (N = 2,144), adjusting for age and sex., Results: Black participants performed worse than white participants on the cognitive tests; 441 participants developed AD. Black participants' incident AD risk was twice that of whites (RR = 1.9; 95% CI, 1.4, 2.7), with 58 excess cases/1,000 occurring among blacks (95% CI, 28, 88). Among noncarriers of APOE ε4, blacks had 2.3 times the AD risk (95% CI, 1.5, 3.6), but among carriers, race was not associated with risk (RR = 1.1; 95% CI, 0.6, 2.0; Pinteraction = 0.05). However, cognitive decline was not faster among blacks: the black-white difference in 5-year change in global cognitive score was 0.007 standard unit (95% CI, -0.034, 0.047). Years of education accounted for a sizable portion of racial disparities in cognitive level and AD risk, in analyses using a counterfactual approach., Conclusions: The higher risk of AD among blacks may stem from lower level of cognitive test performance persisting throughout the observation period rather than faster rate of late-life cognitive decline. Disparities in educational attainment may contribute to these performance disparities. See video abstract at, http://links.lww.com/EDE/B299.

Objective: To examine if incident and preexisting diabetes mellitus (DM) were associated with cognitive decline among African Americans (AAs) and European Americans (EAs)., Methods: Based on a prospective study of 7,740 older adults (mean age 72.3 years, 64% AA, 63% female), DM was ascertained by hypoglycemic medication use and Medicare claims during physician or hospital visits, and cognition by performance on a brief battery for executive functioning, episodic memory, and Mini-Mental State Examination (MMSE). Decline in composite and individual tests among those with incident DM, with preexisting DM, and without DM was studied using a linear mixed effects model with and without change point., Results: At baseline, 737 (15%) AAs and 269 (10%) EAs had preexisting DM. Another 721 (17%) AAs and 289 (12%) EAs had incident DM in old age. Following incident DM, cognitive decline increased by 36% among AAs and by 40% among EAs compared to those without DM. No significant difference was observed between AAs and EAs (p = 0.64). However, cognitive decline increased by 17% among AAs with preexisting DM compared to those without DM, but no increased decline was observed among EAs with preexisting DM. In secondary analyses, faster decline in executive functioning and episodic memory was observed following incident DM., Conclusions: In old age, faster cognitive decline was present among AAs and EAs following incident DM, compared to cognitive decline prior to DM, and among those without DM. This underscores the need for stronger prevention and control of DM in old age., (© 2016 American Academy of Neurology.)

Objective: The study aim was to identify factors associated with racial differences in level of cognitive function in old age., Method: Older Black (n = 5,950) and White (n = 3,469) residents of a geographically defined urban community were randomly split into exploratory and confirmatory subgroups. A global measure of cognition was derived from 4 brief performance tests, and potential correlates of cognition (candidates) were selected from demographic, health-related, and experiential measures. In the exploratory subgroup, using a stepwise search algorithm, we examined the cognitive difference by race and then allowed candidate measures and Race × Candidate Measure interactions to enter the model., Results: The cognitive score in the exploratory subgroup (M = 0.257, SD = 0.714) was a mean of 0.403 unit lower in Black persons than White persons (SE = 0.021, p < .001), and race accounted for 7% of cognitive variability. After the candidate selection process, 16 measures were retained, including 12 candidate measures and the 2-way interactions of race with education, age, reading/cognitive activity, and neuroticism. In this model, which accounted for 45% of the variability in global cognition, race was no longer associated with global cognition (coefficient = 0.012, SE = 0.110, p = .912). Findings were replicated in the confirmatory subgroup., Conclusion: These cross-sectional analyses suggest that consideration of demographic, health-related, and experiential factors greatly attenuates racial differences in late-life level of cognition. (PsycINFO Database Record, ((c) 2016 APA, all rights reserved).)

Purpose: Little research has looked beyond individual factors to consider the influence of the neighborhood environment on cognitive function. A greater density of physical resources (e.g., recreational centers and parks) and institutional resources (e.g., community centers) may buffer cognitive decline by offering opportunities for physical activity and social interaction., Methods: Using data from the Chicago Health and Aging Project (1993-2011), a prospective cohort study of 6518 adults of age 65 years or older, we fit a three-level growth curve model to examine the role of individual and neighborhood factors (objectively observed at the block group level) on trajectories of cognitive function (composite of East Boston Memory Test, symbol digit test, and Mini Mental State Examination) in later life., Results: Net of individual factors, residence in a neighborhood with community resources, proximity to public transit, and public spaces in good condition were associated with slower rates of cognitive decline, possibly by increasing opportunities for social and physical activities or access to destinations that facilitate engagement in activities., Conclusions: These results highlight the role of neighborhood environments in buffering cognitive decline among older adults aging in place., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To examine the relation of performance on brief cognitive tests to development of clinically diagnosed Alzheimer disease (AD) dementia over the following 18 years in a sample of African Americans and European Americans., Methods: A composite cognitive test score based on tests of episodic memory, executive function, and global cognition was constructed in a prospective population-based sample of 2,125 participants (55% African American and 61% female) aged 65 years and older residing in 4 Chicago neighborhoods. Time before AD dementia diagnosis was categorized into 6 groups corresponding to data collection periods: 0.1-0.9, 1.0-3.9, 4.0-6.9, 7.0-9.9, 10.0-12.9, and 13.0-17.9 years., Results: Of 2,125 participants without clinical AD dementia, 442 (21%) developed clinical AD dementia over 18 years of follow-up. Lower composite cognitive test scores were associated with the development of AD dementia over the duration of the study. The magnitude of association between composite cognitive test score and development of AD dementia increased from an odds ratio of 3.39 (95% confidence interval 1.72, 6.67; p < 0.001) at 13.0-17.9 years to 9.84 (95% confidence interval 7.41, 13.06; p < 0.001) at 0.1-0.9 years, per SD increment. These associations were consistently larger among European Americans than among African Americans. Performance on individual cognitive tests of episodic memory, executive function, and global cognition also significantly predicted the development of AD dementia, with associations exhibiting a similar trend over 18 years., Conclusions: Our findings suggest that cognitive impairment may manifest in the preclinical phase of AD dementia substantially earlier than previously established., (© 2015 American Academy of Neurology.)