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ObjectivesTo characterize the extent to which brief cognitive assessments administered in the population-representative U.S. Health and Retirement Study (HRS) and its International Partner Studies can be considered to be measuring a single, unidimensional latent cognitive function construct.MethodsCognitive function assessments were administered in face-to-face interviews in 12 studies in 26 countries (N = 155,690), including the U.S. HRS and selected International Partner Studies. We used the time point of the first cognitive assessment for each study to minimize differential practice effects across studies and documented cognitive test item coverage across studies. Using confirmatory factor analysis models, we estimated single-factor general cognitive function models and bifactor models representing memory-specific and nonmemory-specific cognitive domains for each study. We evaluated model fits and factor loadings across studies.ResultsDespite relatively sparse and inconsistent cognitive item coverage across studies, all studies had some cognitive test items in common with other studies. In all studies, the bifactor models with a memory-specific domain fit better than single-factor general cognitive function models. The data fit the models at reasonable thresholds for single-factor models in 6 of the 12 studies and for the bifactor models in all 12 of the 12 studies.DiscussionThe cognitive assessments in the U.S. HRS and its International Partner Studies reflect comparable underlying cognitive constructs. We discuss the assumptions underlying our methods, present alternatives, and future directions for cross-national harmonization of cognitive aging data.

Adverse birth outcomes put children at increased risk of poor future health. They also put families under sudden socioeconomic and psychological strain, which has poorly understood consequences. We tested whether infants experiencing an adverse birth outcome-low birthweight or prematurity, as well as lengthy hospital stays-were more likely to be evicted in early childhood, through age 5 years. We analyzed 5,655 observations contributed by 2,115 participants in the Fragile Families and Child Wellbeing Study-a national, randomly sampled cohort of infants born in large US cities between 1998 and 2000-living in rental housing at baseline. We fitted proportional hazards models using piecewise logistic regression, controlling for an array of confounders and applying inverse probability of selection weights. Having been born low birthweight or preterm was associated with a 1.74-fold increase in children's hazard of eviction (95% confidence interval: 1.02, 2.95), and lengthy neonatal hospital stays were independently associated with a relative hazard of 2.50 (95% confidence interval: 1.15, 5.44) compared with uncomplicated births. Given recent findings that unstable housing during pregnancy is associated with adverse birth outcomes, our results suggest eviction and health may be cyclical and co-constitutive. Children experiencing adverse birth outcomes are vulnerable to eviction and require additional supports.

ObjectiveTo test the hypothesis that life course patterns of employment, marriage, and childrearing influence later-life rate of memory decline among women, we examined the relationship of work-family experiences between ages 16 and 50 years and memory decline after age 55 years among US women.MethodsParticipants were women ages ≥55 years in the Health and Retirement Study. Participants reported employment, marital, and parenthood statuses between ages 16 and 50 years. Sequence analysis was used to group women with similar work-family life histories; we identified 5 profiles characterized by similar timing and transitions of combined work, marital, and parenthood statuses. Memory performance was assessed biennially from 1995 to 2016. We estimated associations between work-family profiles and later-life memory decline with linear mixed-effects models adjusted for practice effects, baseline age, race/ethnicity, birth region, childhood socioeconomic status, and educational attainment.ResultsThere were 6,189 study participants (n = 488 working nonmothers, n = 4,326 working married mothers, n = 530 working single mothers, n = 319 nonworking single mothers, n = 526 nonworking married mothers). Mean baseline age was 57.2 years; average follow-up was 12.3 years. Between ages 55 and 60, memory scores were similar across work-family profiles. After age 60, average rate of memory decline was more than 50% greater among women whose work-family profiles did not include working for pay after childbearing, compared with those who were working mothers.ConclusionsWomen who worked for pay in early adulthood and midlife experienced slower rates of later-life memory decline, regardless of marital and parenthood status, suggesting participation in the paid labor force may protect against later-life memory decline.

RationaleLittle research has evaluated the life course drivers of cognitive aging in South Africa.ObjectivesWe investigated the relationships of self-rated childhood health and father's occupation during childhood with later-life cognitive function score and whether educational attainment mediated these relationships among older South Africans living in a former region of Apartheid-era racial segregation.MethodsData were from baseline assessments of "Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community" (HAALSI), a population-based study of 5059 men and women aged ≥40 years in 2015 in rural Agincourt sub-district, South Africa. Childhood health, father's occupation during childhood, and years of education were self-reported in study interviews. Cognitive measures assessed time orientation, numeracy, and word recall, which were included in a z-standardized latent cognitive function score variable. Linear regression models adjusted for age, sex, and country of birth were used to estimate the total and direct effects of each childhood risk factor, and the indirect effects mediated by years of education.ResultsPoor childhood health predicted lower cognitive scores (total effect = -0.28; 95% CI = -0.35, -0.21, versus good); this effect was not mediated by educational attainment. Having a father in a professional job during childhood, while rare (3% of sample), predicted better cognitive scores (total effect = 0.25; 95% CI = 0.10, 0.40, versus unskilled manual labor, 29% of sample). Half of this effect was mediated by educational attainment. Education was linearly associated with later-life cognitive function score (0.09; 95% CI = 0.09, 0.10 per year achieved).ConclusionIn this post-Apartheid, rural South African context, older adults with poor self-reported childhood health or whose father worked in unskilled manual labor had relatively poor cognitive outcomes. Educational attainment strongly predicted cognitive outcomes, and appeared to be, in part, a mechanism of social stratification in later-life cognitive health in this context.

BackgroundSingle motherhood is associated with poorer health, but whether this association varies between countries is not known. We examine associations between single motherhood and poor later-life health in the USA, England and 13 European countries.MethodsData came from 25 125 women aged 50+ who participated in the US Health and Retirement Study, the English Longitudinal Study of Ageing and Survey of Health, Ageing and Retirement in Europe. We tested whether single motherhood at ages 16-49 was associated with increased risk of limitations with activities of daily living (ADL), instrumental ADL and fair/poor self-rated health in later life.Results33% of American mothers had experienced single motherhood before age 50, versus 22% in England, 38% in Scandinavia, 22% in Western Europe and 10% in Southern Europe. Single mothers had higher risk of poorer health and disability in later life than married mothers, but associations varied between countries. For example, risk ratios for ADL limitations were 1.51 (95% CI 1.29 to 1.98) in England, 1.50 (1.10 to 2.05) in Scandinavia and 1.27 (1.17 to 1.40) in the USA, versus 1.09 (0.80 to 1.47) in Western Europe, 1.13 (0.80 to 1.60) in Southern Europe and 0.93 (0.66 to 1.31) in Eastern Europe. Women who were single mothers before age 20, for 8+ years, or resulting from divorce or non-marital childbearing, were at particular risk.ConclusionsSingle motherhood during early-adulthood or mid-adulthood is associated with poorer health in later life. Risks were greatest in England, the USA and Scandinavia. Selection and causation mechanisms might both explain between-country variation.

ObjectivesWe examined relationships between US women's exposure to midlife work-family demands and subsequent mortality risk.MethodsWe used data from women born 1935 to 1956 in the Health and Retirement Study to calculate employment, marital, and parenthood statuses for each age between 16 and 50 years. We used sequence analysis to identify 7 prototypical work-family trajectories. We calculated age-standardized mortality rates and hazard ratios (HRs) for mortality associated with work-family sequences, with adjustment for covariates and potentially explanatory later-life factors.ResultsMarried women staying home with children briefly before reentering the workforce had the lowest mortality rates. In comparison, after adjustment for age, race/ethnicity, and education, HRs for mortality were 2.14 (95% confidence interval [CI] = 1.58, 2.90) among single nonworking mothers, 1.48 (95% CI = 1.06, 1.98) among single working mothers, and 1.36 (95% CI = 1.02, 1.80) among married nonworking mothers. Adjustment for later-life behavioral and economic factors partially attenuated risks.ConclusionsSequence analysis is a promising exposure assessment tool for life course research. This method permitted identification of certain lifetime work-family profiles associated with mortality risk before age 75 years.

ObjectivesTo assess the association of current and long-term spousal caregiving with risk of depression in a nationally (U.S.) representative sample of older adults.MethodsWe studied married and depression-free Health and Retirement Study respondents aged 50 years and older (n = 9,420) at baseline from 2000 to 2010. Current (≥14 hours per week of help with instrumental/activities of daily living for a spouse in the most recent biennial survey) and long-term caregiving (care at two consecutive surveys) were used to predict onset of elevated depressive symptoms (≥3 on a modified Centers for Epidemiologic Studies Depression scale) with discrete-time hazards models and time-updated exposure and covariate information.ResultsCurrent caregiving was associated with significant elevations in risk of depression onset (hazard ratio: 1.64; Wald χ(2), 1 df: 28.34; p

ObjectivesTo assess the correspondence between self-reported and measured indicators of mobility disability in older adults in six low- and middle-income countries (LMICs).DesignCross-sectional analysis of Study on Global AGEing and Adult Health (SAGE).SettingHousehold surveys in China, India, Russia, South Africa, Ghana, and Mexico.ParticipantsCommunity-dwelling SAGE respondents aged 65 and older (N = 12,215).MeasurementsObjective mobility was assessed according to a 4-m timed walk at normal pace conducted in the respondent's home; slow walking speed was defined according to the Fried frailty criteria (lowest quintile of walking speed, adjusted for age and height). Self-reported mobility difficulty was assessed according to a question about ability to walk 1 km; this response was dichotomized into any versus no self-reported difficulty walking 1 km (reference no difficulty). The age- (5-year groups) and sex-specific probability of self-reporting difficulty walking 1 km was estimated in those with a measured slow walk using logistic regression.ResultsBetween 42% and 76% of people aged 65 and older reported any difficulty walking 1 km. Average walking speed was slowest in Russia (0.61 m/s) and fastest in China (0.88 m/s). The probabilities of reporting any difficulty walking 1 km in women aged 65 to 69, for example, with a slow walk varied (China = 0.35, India = 0.90, Russia = 0.68, South Africa = 0.81, Ghana = 0.91, Mexico = 0.73; test of country differences P < .001). There was significant variation at older ages, albeit smaller in magnitude. Patterns were similar for men.ConclusionAlthough correspondence between an objective and self-reported measure of mobility was generally high, correspondence differed significantly between LMICs. International comparisons of self-reported disability measures for clinical, prevention, and policy guidelines in LMICs should consider that self-reported data may not correspond to objective measures uniformly between countries.

Aim To investigate mid-life employment trajectories in relation to later-life memory function and rate of decline in rural South Africa. Methods Data from the Agincourt Health and Socio-Demographic Surveillance System were linked to the 'Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa' (HAALSI) in rural Agincourt, South Africa (N  =   3133). Employment was assessed every 4 years over 2000–12 as being employed (0, 1, 2 and ≥3 time points), being employed in a higher-skill occupation (0, 1, 2 and ≥3 time points) and dynamic employment trajectories identified using sequence analysis. Latent memory z-scores were assessed over 2014–22. Mixed-effects linear regression models were fitted to examine the associations of interest. Results Sustained mid-life employment from 2000–12 (β = 0.052, 95% CI: -0.028 to 0.132, 1 vs 0 time points; β = 0.163, 95% CI: 0.077 to 0.250, 2 vs 0 time points; β = 0.212, 95% CI: 0.128 to 0.296, ≥3 vs 0 time points) and greater time spent in a higher-skill occupation (β = 0.077, 95% CI: -0.020 to 0.175, 1 vs 0 time points; β = 0.241, 95% CI: 0.070 to 0.412, 2 vs 0 time points; β = 0.361, 95% CI: 0.201 to 0.520, ≥3 vs 0 time points) were associated with higher memory scores in 2014/15, but not subsequent rate of memory decline. Moving from a lower-skill to higher-skill occupation was associated with higher memory function, but a faster rate of decline over 2014–22. Conclusions Sustained mid-life employment, particularly in higher-skill occupations, may contribute to later-life memory function in this post-Apartheid South African setting. [ABSTRACT FROM AUTHOR]

In this commentary, invited for the 100th anniversary of the Journal , we discuss the addition of randomized experiments, along with natural experiments that emulate randomized trials using observational data, as designs in the social epidemiologist's toolbox. These approaches transform the way we define and ask questions about social exposures. They compel us to ask questions about how well-defined interventions change a social exposure that might lead to changes in health. As such, experiments are of unique public health and policy significance. We argue that they are a powerful approach to advance our understanding of how well-defined changes in social exposures impact health, and how credible social policy reforms may be instrumental to address health inequalities. We focus on two research designs. The first is a "pure" randomized controlled trial (RCT) in which the investigator defines and randomly assigns the intervention. The second is a natural experiment, which exploits the fact that policies or interventions in the real world often involve an element of random assignment, emulating an RCT. To give the reader our bottom line: While acknowledging their limits, we continue to be very excited about the promise of RCTs and natural experiments to advance social epidemiology. [ABSTRACT FROM AUTHOR]

Telomere length (TL) may be a biomarker of aging processes as well as age-related diseases. However, most studies of TL and aging are conducted in high-income countries. Less is known in low- and middle-income countries (LMICs) such as South Africa, where life expectancy remains lower despite population aging. We conducted a descriptive analysis of TL in a cohort of older adults in rural South Africa. TL was assayed from venous blood draws using quantitative polymerase chain reaction (T/S ratio). We examined the correlation between TL and biomarkers, demographic characteristics, mental/cognitive health measures, and physical performance measures in a subsample of the Wave 1 2014–2015 "Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI) cohort (n = 510). We used logistic regression to measure the association between TL and mortality through Wave 3 (2021–2022). In bivariate analyses, TL was significantly correlated with age (r = −0.29, p <.0001), self-reported female sex (r = 0.13, p =.002), mortality (r = −0.1297, p =.003), diastolic blood pressure (r = 0.09, p =.037), pulse pressure (r = −0.09, p =.045), and being a grandparent (r = −0.17, p =.0001). TL was significantly associated with age (β = −0.003; 95% confidence interval [CI] = −0.005, −0.003). TL was significantly associated in unadjusted multivariate analyses with mortality, but the relationship between TL and mortality was attenuated after adjusting for age (odds ratio [OR] = 0.19; 95% CI = 0.03, 1.27) and other covariates (OR = 0.17; 95% CI = 0.02, 1.19). Our study is the first analysis of TL in an older adult South African population. Our results corroborate existing relationships between TL and age, sex, cardiometabolic disease, and mortality found in higher-income countries. [ABSTRACT FROM AUTHOR]