Association of cumulative loneliness with all-cause mortality among middle-aged and older adults in the United States, 1996 to 2019.

Loneliness is a growing public health concern worldwide. We characterized the association between cumulative loneliness and subsequent all-cause mortality, using data from 9,032 participants aged 50+ in the population-based US Health and Retirement Study (HRS) from 1996 to 2019. Loneliness status (yes; no) was measured biennially from 1996 to 2004, and we categorized the experience of cumulative loneliness over the 8-y period as never, one time point, two time points, and ≥three time points. A multivariable-adjusted age-stratified Cox proportional hazards regression model was fitted to examine the association between cumulative loneliness from 1996 to 2004 and all-cause mortality from 2004 to 2019. Excess deaths due to each category of cumulative loneliness were calculated. Compared to those who never reported loneliness from 1996 to 2004, participants experiencing loneliness at one time point, two time points, and ≥three time points respectively had 1.05 (95% CI: 0.96 to 1.15), 1.06 (95% CI: 0.95 to 1.19), and 1.16 (95% CI: 1.02 to 1.33) times higher hazards of mortality from 2004 to 2019 (P trend = 0.01). These results correspond to 106 (95% CI: 68 to 144), 202 (95% CI: 146 to 259), and 288 (95% CI: 233 to 343) excess deaths per 10,000 person-years, for those experiencing loneliness at each of one, two, or ≥three time points from 1996 to 2004. Cumulative loneliness in mid-to-later life may thus be a mortality risk factor with a notable impact on excess mortality. Loneliness may be an important target for interventions to improve life expectancy in the United States.

Could differential under-reporting of loneliness between men and women bias the gender-specific association between loneliness duration and rate of memory decline? A probabilistic bias analysis of effect modification.

Gender is an observed effect modifier of the association between loneliness and memory aging. However, this effect modification may be a result of information bias due to differential loneliness under-reporting by gender. We applied probabilistic bias analyses to examine whether effect modification of the loneliness-memory decline relationship by gender is retained under three simulation scenarios with various magnitudes of differential loneliness under-reporting between men and women. Data were from biennial interviews with adults aged 50+ in the US Health and Retirement Study from 1996-2016 (5,646 women and 3,386 men). Loneliness status (yes vs. no) was measured from 1996-2004 using the CES-D loneliness item and memory was measured from 2004-2016. Simulated sensitivity and specificity of the loneliness measure were informed by a validation study using the UCLA Loneliness Scale as a gold standard. The likelihood of observing effect modification by gender was higher than 90% in all simulations, although the likelihood reduced with an increasing difference in magnitude of the loneliness under-reporting between men and women. The gender difference in loneliness under-reporting did not meaningfully affect the observed effect modification by gender in our simulations. Our simulation approach may be promising to quantify potential information bias in effect modification analyses.

Mid-life household food insecurity and subsequent memory function and rate of decline in rural South Africa, 2004-2022.

INTRODUCTION: We aimed to investigate mid-life food insecurity over time in relation to subsequent memory function and rate of decline in Agincourt, rural South Africa. METHODS: Data from the longitudinal Agincourt Health and Socio-Demographic Surveillance System (Agincourt HDSS) were linked to the population-representative Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI). Food insecurity (yes vs. no) and food insecurity intensity (never/rarely/sometimes vs. often/very often) in the past month were assessed every 3 years from 2004-2013 in Agincourt HDSS. Cumulative exposure to each food insecurity measure was operationalized as 0, 1, and ≥2 time points. Episodic memory was assessed from 2014/15-2021/22 in HAALSI. Mixed-effects linear regression models were fitted to investigate the associations of each food insecurity measure with memory function and rate of decline over time. RESULTS: A total of 3,186 participants (mean age [SD] in 2004: 53 [12.87]; range: 30-96) were included and 1,173 (36%) participants experienced food insecurity in 2004, while this figure decreased to 490 (15%) in 2007, 489 (15%) in 2010, and 150 (5%) in 2013. Experiencing food insecurity at one time point (vs. never) from 2004-2013 was associated with lower baseline memory function (ß=-0.095; 95% CI: -0.159 to -0.032) in 2014/15 but not rate of memory decline. Higher intensity of food insecurity at ≥ two time points (vs. never) was associated with lower baseline memory function (ß =-0.154, 95% CI: -0.338 to 0.028), although the estimate was imprecise. Other frequencies of food insecurity and food insecurity intensity were not associated with memory function or decline in the fully adjusted models. CONCLUSION: In this setting, mid-life food insecurity may be a risk factor for lower later-life memory function, but not decline.

Does education moderate gender disparities in later-life memory function? A cross-national comparison of harmonized cognitive assessment protocols in the United States and India.

INTRODUCTION: We compared gender disparities in later-life memory, overall and by education, in India and the United States (US). METHODS: Data (N = 7443) were from harmonized cognitive assessment protocols (HCAPs) in the Longitudinal Aging Study of India-Diagnostic Assessment of Dementia (LASI-DAD; N = 4096; 2017-19) and US Health and Retirement Study HCAP (HRS-HCAP; N = 3347; 2016-17). We derived harmonized memory factors from each study using confirmatory factor analysis. We used multivariable-adjusted linear regression to compare gender disparities in memory function between countries, overall and by education. RESULTS: In the United States, older women had better memory than older men (0.28 SD-unit difference; 95% CI: 0.22, 0.35). In India, older women had worse memory than older men (-0.15 SD-unit difference; 95% CI: -0.20, -0.10), which attenuated with increasing education and literacy. CONCLUSION: We observed gender disparities in memory in India that were not present in the United States, and which dissipated with education and literacy.

Cross-national comparisons of later-life cognitive function using data from the Harmonized Cognitive Assessment Protocol (HCAP): Considerations and recommended best practices.

The Harmonized Cognitive Assessment Protocol (HCAP) is a major innovation that provides, for the first time, harmonized data for cross-national comparisons of later-life cognitive functions that are sensitive to linguistic, cultural, and educational differences across countries. However, cognitive function does not lend itself to direct comparison across diverse populations without careful consideration of the best practices for such comparisons. This perspective discusses theoretical and methodological considerations and offers a set of recommended best practices for conducting cross-national comparisons of risk factor associations using HCAP data. Because existing and planned HCAP studies provide cognition data representing an estimated 75% of the global population ≥65 years of age, these recommended best practices will support high-quality comparative analyses of cognitive aging around the world. The principles described in this perspective are applicable to any researcher aiming to integrate or compare harmonized data on cognitive outcomes and their risk and protective factors across diverse populations.

Lifetime occupational skill and later-life cognitive function among older adults in the United States, Mexico, India, and South Africa.

INTRODUCTION: We conducted a cross-national comparison of the association between main lifetime occupational skills and later-life cognitive function across four economically and socially distinct countries. METHODS: Data were from population-based studies of aging and their Harmonized Cognitive Assessment Protocols (HCAPs) in the US, South Africa, India, and Mexico (N = 10,037; Age range: 50 to 105 years; 2016 to 2020). Main lifetime occupational skill was classified according to the International Standard Classification of Occupations. Weighted, adjusted regression models estimated pooled and country-specific associations between main lifetime occupational skill and later-life general cognitive function in men and women. RESULTS: We observed positive gradients between occupational skill and later-life cognitive function for men and women in the US and Mexico, a positive gradient for women but not men in India, and no association for men or women in South Africa. DISCUSSION: Main lifetime occupations may be a source of later-life cognitive reserve, with cross-national heterogeneity in this association. HIGHLIGHTS: No studies have examined cross-national differences in the association of occupational skill with cognition. We used data from Harmonized Cognitive Assessment Protocols in the US, Mexico, India, and South Africa. The association of occupational skill with cognitive function varies by country and gender.

Association of cancer history with structural brain aging markers of Alzheimer's disease and related dementias risk.

INTRODUCTION: Cancer survivors are less likely than comparably aged individuals without a cancer history to develop Alzheimer's disease and related dementias (ADRD). METHODS: In the UK Biobank, we investigated associations between cancer history and five structural magnetic resonance imaging (MRI) markers for ADRD risk, using linear mixed-effects models to assess differences in mean values and quantile regression to examine whether associations varied across the distribution of MRI markers. RESULTS: Cancer history was associated with smaller mean hippocampal volume (b = -19 mm3 , 95% CI = -36, -1) and lower mean cortical thickness in the Alzheimer's disease signature region (b = -0.004 mm, 95% CI = -0.007, -0.000). Quantile regressions indicated individuals most vulnerable to ADRD were more affected by cancer history. DISCUSSION: Some brain MRI markers associated with ADRD risk were elevated in adults with a history of cancer. The magnitude of the adverse associations varied across quantiles of neuroimaging markers, and the pattern suggests possible harmful associations for individuals already at high ADRD risk. HIGHLIGHTS: We found no evidence of an inverse association between cancer history and ADRD-related neurodegeneration. Cancer history was associated with smaller mean hippocampal volume and lower mean cortical thickness in the Alzheimer's disease signature region. Quantile regressions indicated individuals most vulnerable to ADRD were more affected by cancer history.

Association between cancer and dementia risk in the UK Biobank: evidence of diagnostic bias.

Epidemiological studies have identified an inverse association between cancer and dementia. Underlying methodological biases have been postulated, yet no studies have systematically investigated the potential for each source of bias within a single dataset. We used the UK Biobank to compare estimates for the cancer-dementia association using different analytical specifications designed to sequentially address multiple sources of bias, including competing risk of death, selective survival, confounding bias, and diagnostic bias. We included 140,959 UK Biobank participants aged ≥ 55 without dementia before enrollment and with linked primary care data. We used cancer registry data to identify cancer cases prevalent before UK Biobank enrollment and incident cancer diagnosed after enrollment. We used Cox models to evaluate associations of prevalent and incident cancer with all-cause dementia, Alzheimer's disease (AD), and vascular dementia. We used time-varying models to evaluate diagnostic bias. Over a median follow-up of 12.3 years, 3,310 dementia cases were diagnosed. All-site incident cancer was positively associated with all-cause dementia incidence (hazard ratio [HR] = 1.14, 95% CI: 1.02-1.29), but prevalent cancer was not (HR = 1.04, 95% CI: 0.92-1.17). Results were similar for vascular dementia. AD was not associated with prevalent or incident cancer. Dementia diagnosis was substantially elevated in the first year after cancer diagnosis (HR = 1.83, 95% CI: 1.42-2.36), after which the association attenuated to null, suggesting diagnostic bias. Following a cancer diagnosis, health care utilization or cognitive consequences of diagnosis or treatment may increase chance of receiving a dementia diagnosis, creating potential diagnostic bias in electronic health records-based studies.

Rural/urban differences in mental health and social well-being among older US adults in the early months of the COVID-19 pandemic.

OBJECTIVES: This study seeks to identify differences in mental health and social well-being during the early months of the COVID-19 pandemic among older adults by rural/urban location. METHODS: We use data from the COVID-19 Coping Study, a nation-wide online study of U.S. adults aged 55 and older (n = 6,873) fielded during April-May, 2020. We investigated rural/urban differences in mental health (depressive symptoms and anxiety symptoms) and social well-being (loneliness and social isolation); concern about COVID-19; and types of social participation (e.g. phone/video calls, visits). We also used multivariable logistic regression models to assess the relationship of rurality with mental health, adjusting for socio-demographic correlates, COVID-19 history, and COVID-19 concern. RESULTS: We found similar prevalence of mental health and social well-being outcomes for rural and urban respondents. Rural respondents reported lower concern about COVID-19 and more frequent use of social media than urban respondents. CONCLUSION: Mental health and social well-being did not differ by rural/urban location in the early months of the COVID-19 pandemic. However, rural residents reported less concern about COVID-19 and more use of social media, potentially leading to greater risk of illness from the pandemic in later months.

Cumulative loneliness and subsequent memory function and rate of decline among adults aged ≥50 in the United States, 1996 to 2016

INTRODUCTION: The study objective was to investigate the association between loneliness duration and memory function over a 20-year period. METHODS: Data were from 9032 adults aged ≥50 in the Health and Retirement Study. Loneliness status (yes vs. no) was assessed biennially from 1996 to 2004 and its duration was categorized as never, 1 time point, 2 time points, and ≥3 time points. Episodic memory was assessed from 2004 to 2016 as a composite of immediate and delayed recall trials combined with proxy-reported memory. Mixed-effects linear regression models were fitted. RESULTS: A longer duration of loneliness was associated with lower memory scores (P < 0.001) and a faster rate of decline (P < 0.001). The association was stronger among adults aged ≥65 than those aged <65 (three-way interaction P = 0.013) and was stronger among women than men (three-way interaction P = 0.002). DISCUSSION: Cumulative loneliness may be a salient risk factor for accelerated memory aging, especially among women aged ≥65. HIGHLIGHT: A longer duration of loneliness was associated with accelerated memory aging. The association was stronger among women than men and among older adults than the younger. Reducing loneliness in mid- to late life may help maintain memory function.

Effects of Pension Eligibility Expansion on Men's Cognitive Function: Findings from Rural South Africa.

Two-thirds of people living with Alzheimer's disease and related dementias (ADRD) live in low- and middle-income countries, and this figure is expected to rise as these populations are rapidly aging. Since evidence demonstrates links between socioeconomic status and slower rates of cognitive decline, protecting older adults' cognitive function in resource-limited countries that lack the infrastructure to cope with ADRD is crucial to reduce the burden it places on these populations and their health systems. While cash transfers are a promising intervention to promote healthy cognitive aging, factors such as household wealth and level of education often confound the ability to make causal inferences on the impact of cash transfers and cognitive function. This study uses a quasi-experimental design, leveraging an exogenous expansion to the Old Age Pension for men in South Africa, to approximate causal associations with cognitive function. We found evidence that there is a potential benefit of cash transfers at an earlier age for older individuals. As such, transfers such as pensions or other forms of direct basic income transfers may hold promise as potential interventions to promote healthy cognitive aging.

Changes in Life Expectancy and Disability-Free Life Expectancy in Successive Birth Cohorts of Older Cancer Survivors: A Longitudinal Modeling Analysis of the US Health and Retirement Study.

The population of older cancer survivors in the United States is rapidly growing. However, little is currently known about how the health of older cancer survivors has changed over time and across successive birth cohorts. Using data from the US Health and Retirement Study, we parameterized a demographic microsimulation model to compare partial cohort life expectancy (LE) and disability-free LE for US men and women without cancer and with prevalent and incident cancer diagnoses for 4 successive 10-year birth cohorts, born 1918-1927 to 1948-1957. Disability was defined as being disabled in ≥1 activity of daily living. These cohorts had midpoint ages of 55-64, 65-74, and 75-84 years during the periods 1998-2008 (the "early" period) and 2008-2018 (the "later" period). Across all cohorts and periods, those with incident cancer had the lowest LE, followed by those with prevalent cancer and cancer-free individuals. We observed declines in partial LE and an expansion of life spent disabled among more recent birth cohorts of prevalent-cancer survivors. Our findings suggest that advances in treatments that prolong life for individual cancer patients may have led to population-level declines in conditional LE and disability-free LE across successive cohorts of older cancer survivors.

New directions in cancer and aging: State of the science and recommendations to improve the quality of evidence on the intersection of aging with cancer control.

BACKGROUND: The global population of older cancer survivors is growing. However, the intersections of aging-related health risks across the cancer control continuum are poorly understood, limiting the integration of aging into cancer control research and practice. The objective of this study was to review the state of science and provide future directions to improve the quality of evidence in 6 priority research areas in cancer and aging. METHODS: The authors identified priority research areas in cancer and aging through an evidence-based Research Jam process involving 32 investigators and trainees from multiple disciplines and research centers in aging and cancer; then, they conducted a narrative review of the state of the science and future directions to improve the quality of evidence in these research areas. Priority research areas were defined as those in which gaps in scientific evidence or clinical practice limit the health and well-being of older adults with cancer. RESULTS: Six priority research areas were identified: cognitive and physical functional outcomes of older cancer survivors, sampling issues in studies of older cancer survivors, risk and resilience across the lifespan, caregiver support and well-being, quality of care for older patients with cancer, and health disparities. Evidence in these areas could be improved through the incorporation of bias reduction techniques into longitudinal studies of older cancer survivors, novel data linkage, and improved representation of older adults in cancer research. CONCLUSIONS: The priority research areas and methodologies identified here may be used to guide interdisciplinary research and improve the quality of evidence on cancer and aging.

Does a Cancer Diagnosis in Mid-to-Later Life Modify Racial Disparities in Memory Aging?

BACKGROUND: It is unknown whether an incident cancer diagnosis differentially impacts acute and long-term memory aging between older White and Black Americans. METHODS: Incident cancer diagnoses and memory (immediate and delayed recall, combined with proxy-reported memory) were assessed at biennial study interviews in the US Health and Retirement Study (N=14,235, 1998-2016). We used multivariable segmented linear mixed-effects models to evaluate the rate of change in standardized memory score (SD/decade) in the years before, acutely at the time of, and in the years following an incident cancer diagnosis, compared to cancer-free adults, by race. RESULTS: Black participants experienced faster memory decline than White participants (cancer-free group: -1.211 vs. -1.077; P<0.0001). An incident cancer diagnosis was associated with an acute memory drop in White, but not Black participants (-0.065 vs. 0.024; P<0.0001). However, White cancer survivors experienced slower memory decline than cancer-free White adults before and after diagnosis, but this memory advantage was not observed among Black cancer survivors. CONCLUSIONS: Racial disparities in memory aging are not modified by an incident cancer diagnosis. The acute cancer-related memory decline and long-term memory advantage experienced by White, but not Black, cancer survivors relative to cancer-free older adults, requires further investigation.

Caregiver-reported household food insecurity and child-reported food insecurity in relation to eating disorder risk factors and symptoms among preadolescent children.

OBJECTIVE: To examine the relation of caregiver-reported household food insecurity (FI) and child-reported FI with eating disorder (ED) risk factors and symptoms, including effect modification by gender, in preadolescent children. METHOD: Data were from the Family Food Study, a cross-sectional study of households with incomes ≤200% of the federal poverty line in southeastern Michigan. Children aged 8-10 years (n = 194) and their female primary caregivers reported separately on FI status. Children reported ED risk factors/symptoms via the 24-item Children's Eating Attitudes Test (ChEAT-24), with higher scores indicating more ED risk factors/symptoms. Linear mixed models were used to examine associations between FI measures with the ChEAT-24 total score, plus subscale scores for dieting, food preoccupation, weight preoccupation, vomiting, and social pressure to eat/gain weight. Models were adjusted for child age, child gender, caregiver race/ethnicity, caregiver education, and household income. RESULTS: Among all children, child-reported FI, but not caregiver-reported household FI, was associated with more ED risk factors/symptoms. Child-reported FI (vs. no FI) was associated with higher average ChEAT-24 total score (ß = 2.41, 95% CI: 0.57, 4.25). Child-reported FI was also associated with more food preoccupation, more weight preoccupation, and more social pressure to eat. Caregiver-reported household FI was marginally associated with less dieting in girls, and child-reported FI was associated with more dieting in boys. DISCUSSION: Child-reported FI may be more salient than caregiver-reported household FI as a risk factor for ED-related outcomes in preadolescent children. Gender may modify the association between FI and dieting behavior. PUBLIC SIGNIFICANCE STATEMENT: More child-reported food insecurity, but not parent-reported household food insecurity, was associated with more eating disorder risk factors and symptoms among preadolescent boys and girls. These findings emphasize the need for future studies that investigate the role of food insecurity in the development of eating disorders, especially studies that measure child-reported experience of food insecurity.

Physical isolation and mental health among older US adults during the COVID-19 pandemic: longitudinal findings from the COVID-19 Coping Study.

PURPOSE: We investigated the relationships between physical isolation at home during the period when many US states had shelter-in-place orders and subsequent longitudinal trajectories of depression, anxiety, and loneliness in older adults over a 6 month follow-up. METHODS: Data were from monthly online questionnaires with US adults aged ≥ 55 in the nation-wide COVID-19 Coping Study (April through October 2020, N = 3978). Physical isolation was defined as not leaving home except for essential purposes (0, 1-3, 4-6, and 7 days in the past week), measured at baseline (April-May). Outcomes were depressive symptoms (8-item Center for Epidemiological Studies Depression Scale), anxiety symptoms (5-item Beck Anxiety Inventory), and loneliness (3-item UCLA loneliness scale), measured monthly (April-October). Multivariable, population- and attrition-weighted linear mixed-effects models assessed the relationships between baseline physical isolation with mental health symptoms at baseline and over time. RESULTS: Physical isolation (7 days versus 0 days in the past week) was associated with elevated depressive symptoms (adjusted ß = 0.85; 95% CI 0.10-1.60), anxiety symptoms (adjusted ß = 1.22; 95% CI 0.45-1.98), and loneliness (adjusted ß = 1.06; 95% CI 0.51-1.61) at baseline, but not with meaningful rate of change in these mental health outcomes over time. The symptom burden of each mental health outcome increased with increasing past-week frequency of physical isolation. CONCLUSION: During the early COVID-19 pandemic, physical isolation was associated with elevated depressive symptoms, anxiety symptoms, and loneliness, which persisted over time. These findings highlight the unique and persistent mental health risks of physical isolation at home under pandemic control measures.

Vaccine Hesitancy During the COVID-19 Pandemic: A Latent Class Analysis of Middle-Aged and Older US Adults.

It is important to distinguish between apprehensions that lead to vaccine rejection and those that do not. In this study, we (1) identifed latent classes of individuals by vaccination attitudes, and (2) compared classes of individuals by sociodemographic characteristics COVID-19 vaccination, and risk reduction behaviors. The COVID-19 Coping Study is a longitudinal cohort of US adults aged ≥ 55 years (n = 2358). We categorized individuals into three classes based on the adult Vaccine Hesitancy Scale using latent class analysis (LCA). The associations between class membership and sociodemographic characteristics, COVID-19 vaccination, and other behaviors were assessed using chi-square tests. In total, 88.9% were Vaccine Acceptors, 8.6% were Vaccine Ambivalent, and 2.5% Vaccine Rejectors. At the end, 90.7% of Acceptors, 62.4% of the Ambivalent, and 30.7% of the Rejectors had been vaccinated. The Ambivalent were more likely to be Black or Hispanic, and adopted social distancing and mask wearing behaviors intermediate to that of the Acceptors and Rejectors. Targeting the Vaccine Ambivalent may be an efficient way of increasing vaccination coverage. Controlling the spread of disease during a pandemic requires tailoring vaccine messaging to their concerns, e.g., through working with trusted community leaders, while promoting other risk reduction behaviors.

Teaching Epidemiology Online (Pandemic Edition).

In response to the threat posed by the coronavirus disease 2019 (COVID-19) pandemic, many universities are encouraging or requiring online instruction. Teaching an epidemiology course online is different in many respects from teaching in person. In this article, we review specific approaches and strategies related to teaching epidemiology online during the pandemic and beyond, including a discussion of options for course format, grading and assessment approaches, pandemic-related contingencies, and the use of technology. Throughout this article we present practical, epidemiology-specific teaching examples. Moreover, we also examine 1) how the lessons learned about the practice of epidemiology during the pandemic can be integrated into the didactic content of epidemiology training programs and 2) whether epidemiologic pedagogy and teaching strategies should change in the long term, beyond the COVID-19 pandemic. The pandemic has served to heighten our awareness of concerns related to student health and safety, as well as issues of accessibility, equity, and inclusion. Our goal is to present a practical overview connecting pandemic-era online teaching with thoughts about the future of epidemiologic instruction.

Adverse Childhood Experiences and Rate of Memory Decline From Mid to Later Life: Evidence From the English Longitudinal Study of Ageing.

Evidence on the role of early-life adversity in later-life memory decline is conflicting. We investigated the relationships between adverse childhood experiences (ACEs) and memory performance and rate of decline over a 10-year follow-up among middle-aged and older adults in England. Data were from biennial interviews with 5,223 participants aged 54 years or older in the population-representative English Longitudinal Study of Ageing from 2006/2007 to 2016/2017. We examined self-reports of 9 ACEs prior to age 16 years that related to abuse, household dysfunction, and separation from family. Memory was assessed at each time point as immediate and delayed recall of 10 words. Using linear mixed-effects models with person-specific random intercepts and slopes and adjusted for baseline age, participants' baseline age squared, sex, ethnicity, and childhood socioeconomic factors, we observed that most individual and cumulative ACE exposures had null to weakly negative associations with memory function and rate of decline over the 10-year follow-up. Having lived in residential or foster care was associated with lower baseline memory (adjusted ß = -0.124 standard deviation units; 95% confidence interval: -0.273, -0.025) but not memory decline. Our findings suggest potential long-term impacts of residential or foster care on memory and highlight the need for accurate and detailed exposure measures when studying ACEs in relation to later-life cognitive outcomes.

Incidence of Cognitive Impairment during Aging in Rural South Africa: Evidence from HAALSI, 2014 to 2019.

INTRODUCTION: Despite rapid population aging, there are currently limited data on the incidence of aging-related cognitive impairment in sub-Saharan Africa. We aimed to determine the incidence of cognitive impairment and its distribution across key demographic, social, and health-related factors among older adults in rural South Africa. METHODS: Data were from in-person interviews with 3,856 adults aged ≥40 who were free from cognitive impairment at baseline in the population-representative cohort, "Health and Aging in Africa: a Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI), in Agincourt sub-district, Mpumalanga province, South Africa (2014-19). Cognitive impairment was defined as scoring <1.5 standard deviations below the mean of the baseline distribution of orientation and episodic memory scores. Incidence rates and rate ratios for cognitive impairment were estimated according to key demographic, social, and health-related factors, adjusted for age, sex/gender, and country of birth. RESULTS: The incidence of cognitive impairment was 25.7/1,000 person-years (PY; 95% confidence interval [CI]: 23.0-28.8), weighted for mortality (12%) and attrition (6%) over the 3.5-year mean follow-up (range: 1.5-4.8 years). Incidence increased with age, from 8.9/1,000 PY (95% CI: 5.2-16.8) among those aged 40-44 to 93.5/1,000 PY (95% CI: 75.9-116.3) among those aged 80+, and age-specific risks were similar by sex/gender. Incidence was strongly associated with formal education and literacy, as well as marital status, household assets, employment, and alcohol consumption but not with history of smoking, hypertension, stroke, angina, heart attack, diabetes, or prevalent HIV. CONCLUSIONS: This study presents some of the first incidence rate estimates for aging-related cognitive impairment in rural South Africa. Social disparities in incident cognitive impairment rates were apparent in patterns similar to those observed in many high-income countries.