Publications by Author:

Objectives: This study investigates the association between cohort derived dementia and serologically confirmed SARS-CoV-2 infection, an underexplored phenomena in low-and middle-income countries. Examining this relationship in a rural South African community setting offers insights applicable to broader healthcare contexts.

Methods: Data were collected from Black South Africans in the Mpumalanga province who participated in the Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa. Cohort derived dementia was developed using a predictive model for consensus-based dementia diagnosis. Multinomial logistic regression models estimated the association between predicted dementia probability in 2018 and SARS-CoV-2 infection risk in 2021, controlling for demographics, socioeconomic status, and comorbidities.

Results: Fifty-two percent of the tested participants had serologically confirmed SARS-CoV-2 infections. In the fully adjusted model, cohort derived dementia was significantly associated with over twice the risk of serological diagnosis of COVID-19 (RRR = 2.12, p = 0.045).

Conclusion: Complying with COVID-19 prevention recommendations may be difficult for individuals with impaired cognitive functioning due to their symptoms. Results can inform community-based public health initiatives to reduce COVID-19 transmission among South Africa’s rapidly aging population.

{Cash transfers are a promising but understudied intervention that may protect cognitive function in adults by promoting their cognitive reserve. South Africa has a rapidly ageing population, however, less is known about the nature of association between cash transfers and cognitive function in this setting. We leveraged natural experiments from Child Support Grant (CSG) age-eligibility expansions to investigate the association between duration of CSG eligibility and cognitive function among biological mothers of child beneficiaries in South Africa. We analysed 2014/2015 baseline data from 944 women, aged 40 - 59 years with at least one CSG-eligible child, enrolled in the HAALSI cohort in Agincourt, South Africa. Duration of CSG eligibility for each mother was calculated based on the birth dates of all their children and the CSG age eligibility expansion years. Cognitive function was measured using a cognitive battery administered to the mothers at baseline interview. Linear regression was used to estimate the association between duration of CSG eligibility, dichotomized as low (<=10 years) and high (>10 years) eligibility, and cognitive function z-scores of the mothers. Our study finds that high duration of CSG eligibility, compared to low, was associated with higher cognitive function z-scores in the full sample [β: 0.15 SD; 95% CI: 0.04, 0.26; p-value = 0.01]. In mothers with one to four lifetime children, but not five or more, high duration of CSG eligibility, compared to low, was associated with higher cognitive function z-scores [β: 0.19 SD; 95% CI: 0.05, 0.34

To investigate mid-life employment trajectories in relation to later-life memory function and rate of decline in rural South Africa.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.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.Sustained mid-life employment, particularly in higher-skill occupations, may contribute to later-life memory function in this post-Apartheid South African setting.

Background and PurposeBrain arterial diameters are markers of cerebrovascular disease. Demographic and anatomical factors may influence arterial diameters. We hypothesize that age, sex, height, total cranial volume (TCV), and persistent fetal posterior cerebral artery (fPCA) correlate with brain arterial diameters across populations.MethodsParticipants had a time-of-flight MRA from nine international cohorts. Arterial diameters of the cavernous internal carotid arteries (ICA), middle cerebral arteries (MCA), and basilar artery (BA) were measured using LAVA software. Regression models assessed the association between exposures and brain arterial diameters.ResultsWe included 6,518 participants (mean age: 70 ± 9 years; 41% men). Unilateral fPCA was present in 13.2% and bilateral in 3.2%. Larger ICA, MCA, and BA diameters correlated with older age (Weighted average [WA] per 10 years: 0.18 mm, 0.11 mm, and 0.12 mm), male sex (WA: 0.24 mm, 0.13 mm, and 0.21 mm), and TCV (WA: for one TCV standard deviation: 0.24 mm, 0.29 mm, and 0.18 mm). Unilateral and bilateral fPCAs showed a positive correlation with ICA diameters (WA: 0.39 mm and 0.73 mm) and negative correlation with BA diameters (WA: −0.88 mm and −1.73 mm). Regression models including age, sex, TCV, and fPCA explained on average 15%, 13%, and 25% of the ICA, MCA, and BA diameter interindividual variation, respectively. Using height instead of TCV as a surrogate of head size decreased the R-squared by 3% on average.ConclusionBrain arterial diameters correlated with age, sex, TCV, and fPCA. These factors should be considered when defining abnormal diameter cutoffs across populations.

ABSTRACTTwo-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.

Objectives. To examine whether workplace interventions to increase workplace flexibility and supervisor support and decrease work–family conflict can reduce cardiometabolic risk. Methods. We randomly assigned employees from information technology (n = 555) and long-term care (n = 973) industries in the United States to the Work, Family and Health Network intervention or usual practice (we collected the data 2009–2013). We calculated a validated cardiometabolic risk score (CRS) based on resting blood pressure, HbA1c (glycated hemoglobin), HDL (high-density lipoprotein) and total cholesterol, height and weight (body mass index), and tobacco consumption. We compared changes in baseline CRS to 12-month follow-up. Results. There was no significant main effect on CRS associated with the intervention in either industry. However, significant interaction effects revealed that the intervention improved CRS at the 12-month follow-up among intervention participants in both industries with a higher baseline CRS. Age also moderated intervention effects: older employees had significantly larger reductions in CRS at 12 months than did younger employees. Conclusions. The intervention benefited employee health by reducing CRS equivalent to 5 to 10 years of age-related changes for those with a higher baseline CRS and for older employees. Trial Registration. ClinicalTrials.gov Identifier: NCT02050204. (Am J Public Health. 2023;113(12):1322–1331. https://doi.org/10.2105/AJPH.2023.307413)

INTRODUCTION We describe the development and feasibility of using an online consensus approach for diagnosing cognitive impairment and dementia in rural South Africa.

METHODS Cognitive assessments, clinical evaluations, and informant interviews from Cognition and Dementia in the Health and Aging in Africa Longitudinal Study (HAALSI Dementia) were reviewed by an expert panel using a web-based platform to assign a diagnosis of cognitively normal, mild cognitive impairment (MCI), or dementia.

RESULTS Six hundred thirty-five participants were assigned a final diagnostic category, with 298 requiring adjudication conference calls. Overall agreement between each rater's independent diagnosis and final diagnosis (via the portal or consensus conference) was 78.3%. A moderate level of agreement between raters’ individual ratings and the final diagnostic outcomes was observed (average κ coefficient = 0.50).

DISCUSSION Findings show initial feasibility in using an online consensus approach for the diagnosis of cognitive impairment and dementia in remote, rural, and low-resource settings.

Cognitive function is an indicator for global physical and mental health, and cognitive impairment has been associated with poorer life outcomes and earlier mortality. A standard cognition test, adapted to a rural-dwelling African community, and the Oxford Cognition Screen-Plus were used to capture cognitive performance as five continuous traits (total cognition score, verbal episodic memory, executive function, language, and visuospatial ability) for 2,246 adults in this population of South Africans. A novel common variant, rs73485231, reached genome-wide significance for association with episodic memory using data for ~14 million markers imputed from the H3Africa genotyping array data. Window-based replication of previously implicated variants and regions of interest support the discovery of African-specific associated variants despite the small population size and low allele frequency. This African genome-wide association study identifies suggestive associations with general cognition and domain-specific cognitive pathways and lays the groundwork for further genomic studies on cognition in Africa.

Objective:More than one in four adults over 40 years with HIV in South Africa are unaware of their status and not receiving antiretroviral therapy (ART). HIV self-testing may offer a powerful approach to closing this gap for aging adults. Here, we report the results of a randomized comparative effectiveness trial of three different home-based HIV testing strategies for middle-aged and older adults in rural South Africa.Design:Two thousand nine hundred and sixty-three individuals in the ‘Health and Ageing in Africa: a Longitudinal Study of an INDEPTH Community in South Africa (HAALSI)’ cohort study were randomized 1 : 1 : 1 to one of three types of home-based and home-delivered HIV testing modalities: rapid testing with counseling; self-testing, and both rapid testing with counselling and self-testing.Method:In OLS regression analyses, we estimated the treatment effects on HIV testing and HIV testing frequency at about 1 year after delivery. Finally, we assessed the potential adverse effects of these strategies on the secondary outcomes of depressive symptom as assessed by the CESD-20, linkage to care, and risky sexual behavior.Results:

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-value<0.0001), self-reported female sex (r=0.13, p-value=0.002), mortality (r=-0.1297, p-value=0.003), diastolic blood pressure (r=0.09, p-value=0.037), pulse pressure (r=-0.09, p-value=0.045), and being a grandparent (r=-0.17, p-value=0.0001). TL was significantly associated with age (β=-0.003; 95% 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 (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.

Background Social capital theory conceptualizes accessed status (the socioeconomic status of social contacts) as interpersonal resources that generate positive health returns, while social cost theory suggests that accessed status can harm health due to the sociopsychological costs of generating and maintaining these relationships. Evidence for both hypotheses has been observed in higher-income countries, but not in more resource-constrained settings. We therefore investigated whether the dual functions of accessed status on health may be patterned by its interaction with network structure and functions among an older population in rural South Africa. Method We used baseline survey data from the HAALSI study (“Health and Aging in Africa: a Longitudinal Study of an INDEPTH Community in South Africa”) among 4,379 adults aged 40 and older. We examined the direct effect of accessed status (measured as network members’ literacy), as well as its interaction with network size and instrumental support, on life satisfaction and self-rated health. Results In models without interactions, accessed status was positively associated with life satisfaction but not self-rated health. Higher accessed status was positively associated with both outcomes for those with fewer personal contacts. Interaction effects were further patterned by gender, being most health-protective for women with a smaller network and most health-damaging for men with a larger network. Conclusions Supporting social capital theory, we find that having higher accessed status is associated with better health and well-being for older adults in a setting with limited formal support resources. However, the explanatory power of both theories appears to depending on other key factors, such as gender and network size, highlighting the importance of contextualizing theories in practice.

Material resources owned by households that affect daily living conditions may be salient for cognitive health during aging, especially in low-income settings, but there is scarce evidence on this topic. We investigated relationships between long-term trends in household material resources and cognitive function among older adults in a population-representative study in rural South Africa. Data were from baseline interviews with 4580 adults aged ≥40 in “Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI) in 2014/2015 linked to retrospective records on their household material resources from the Agincourt Health and Socio-Demographic Surveillance System (HDSS) from 2001 to 2013. Household material resources were assessed biennially in the Agincourt HDSS using a five-point index that captured dwelling materials, water and sanitation, sources of power, livestock, and technological amenities. Cognitive function was assessed in HAALSI and analyzed as a z-standardized latent variable capturing time orientation, episodic memory, and numeracy. We evaluated the relationships between quintiles of each of the mean resource index score, volatility in resource index score, and change in resource index score and subsequent cognitive function, overall and by resource type. Higher mean household resources were positively associated with cognitive function (βadj = 0.237 standard deviation [SD] units for the highest vs. lowest quintile of mean resource index score; 95% CI: 0.163–0.312; p-trend<0.0001), as were larger improvements over time in household resources (βadj = 0.122 SD units for the highest vs. lowest quintile of change in resources; 95% CI: 0.040–0.205; p-trend = 0.001). Results were robust to sensitivity analyses assessing heterogeneity by age and restricting to those with formal education. The findings were largely driven by technological amenities including refrigerators, stoves, telephones, televisions, and vehicles. These amenities may support cognitive function through improving nutrition and providing opportunities for cognitive stimulation through transportation and social contact outside of the home.

Background: With aging, many people develop Alzheimer’s disease or related dementias (ADRD) as well as chronic physical health problems. The consequent care needs can be complicated, with heavy demands on families, households and communities, especially in resource-constrained settings with limited formal care services. However, research on ADRD caregiving is largely limited to primary caregivers and high-income countries. Our objectives are to analyse in a rural setting in South Africa: (1) how extended households provide care to people with ADRD; and (2) how the health and wellbeing of all caregivers are affected by care roles.
Methods: The study will take place at the Agincourt health and socio-demographic surveillance system site of the MRC/Wits Rural Public Health and Health Transitions Research Unit in Mpumalanga Province, northeast South Africa. We will recruit 100 index individuals predicted to currently have ADRD or cognitive impairment using data from a recent dementia survey. Quantitative surveys will be conducted with each index person’s nominated primary caregiver, all other household members aged over 12, and caregiving non-resident kin and non-kin to determine how care and health are patterned across household networks. Qualitative data will be generated through participant observation and in-depth interviews with caregivers, select community health workers and key informants. Combining epidemiological, demographic and anthropological methods, we will build a rich picture of households of people with ADRD, focused on caregiving demands and capacity, and of caregiving’s effects on health.
Discussion: Our goal is to identify ways to mitigate the negative impacts of long-term informal caregiving for ADRD when formal supports are largely absent. We expect our findings to inform the development of locally relevant and community-oriented interventions to improve the health of caregivers and recipients, with implications for other resource-constrained settings in both higher- and lower-income countries.

We sought to characterize the relationship between alcohol consumption and sexual risk-taking in an aging population in rural South Africa. A cross-sectional analysis was conducted using baseline data from the Health and Ageing in Africa: a Longitudinal Study of an INDEPTH Community (HAALSI) cohort. We elicited information on sexual risk behavior and self-reported frequency of alcohol consumption among 5059 adults ≥ 40 years old. Multivariable models showed that more frequent alcohol consumption is associated with a higher number of sexual partners (β: 1.38, p < .001) and greater odds of having sex for money (OR: 42.58, p < .001) in older adults in South Africa. Additionally, daily drinkers were more likely to have sex without a condom (OR: 2.67, p = .01). Older adults who drank more alcohol were more likely to engage in sexual risk-taking. Behavioral interventions to reduce alcohol intake should be considered to reduce STI and HIV transmission.

KEY FEATURES: The Health and Aging in Africa Longitudinal Study of an INDEPTH Community in South Africa (HAALSI) is a harmonized sister study to the US Health and Retirement Study (HRS). Established in 2015, it includes 5059 individuals aged 40 and over, in a rural community in Agincourt, South Africa.

In light of the projected rise of dementia burden in sub-Saharan Africa, the HAALSI Dementia study was launched in 2019 to investigate the prevalence, incidence and risk factors of cognitive decline and dementia in South Africa.

The HAALSI Dementia sample includes 635 individuals, 50 years and older, of whom 99 also participated in an ancillary magnetic resonance imaging (MRI) sub-study.
The HAALSI Dementia study encompasses a comprehensive, culturally sensitive cognitive battery with multidomain psychometric scales, informant interviews and neurological evaluations, and has sufficient overlap with international Harmonized Cognitive Assessment Protocol (HCAP) and HRS studies to enable cross-calibration.

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.

Objectives Multimorbidity is associated with mortality in high-income countries. Our objective was to investigate the relationship between multimorbidity (>=2 of the following chronic medical conditions: hypertension, diabetes, dyslipidaemia, anaemia, HIV, angina, depression, post-traumatic stress disorder, alcohol dependence) and all-cause mortality in an older, rural black South African population. We further investigated the relationship between HIV multimorbidity (HIV as part of the multimorbidity cluster) and mortality, while testing for the effect of frailty in all models.Design Population cohort study.Setting Agincourt subdistrict of Mpumalanga province, South Africa.Participants 4455 individuals (54.7% female), aged >=40 years (median age 61 years, IQR 52–71) and resident in the study area.Primary and secondary outcome measures The primary outcome measure was time to death and the secondary outcome measure was likelihood of death within 2 years of the initial study visit. Mortality was determined during annual population surveillance updates.Results 3157 individuals (70.9%) had multimorbidity; 29% of these had HIV. In models adjusted for age and sociodemographic factors, multimorbidity was associated with greater risk of death (women: HR 1.72; 95% CI: 1.18 to 2.50; men: HR 1.46; 95% CI: 1.09 to 1.95) and greater odds of dying within 2 years (women: OR 2.34; 95% CI: 1.32 to 4.16; men: OR 1.51; 95% CI: 1.02 to 2.24). HIV multimorbidity was associated with increased risk of death compared with non-HIV multimorbidity in men (HR 1.93; 95% CI: 1.05 to 3.54), but was not statistically significant in women (HR 1.85; 95% CI: 0.85 to 4.04); when detectable, HIV viral loads were higher in men (p=0.021). Further adjustment for frailty slightly attenuated the associations between multimorbidity and mortality risk (women: HR 1.55; 95% CI: 1.06 to 2.26; men: HR 1.36; 95% CI: 1.01 to 1.82), but slightly increased associations between HIV multimorbidity and mortality risk.Conclusions Multimorbidity is associated with mortality in this older black South African population. Health systems which currently focus on HIV should be reorganised to optimise identification and management of other prevalent chronic diseases.Data are available in a public, open access repository. Data are available upon reasonable request. The HAALSI baseline data are publicly available at the Harvard Centre for Population and Development Studies (HCPDS) programme website [www.haalsi.org]. Data are also accessible through the Inter-university Consortium for Political and Social Research (ICPSR) at the University of Michigan [www.icpsr.umich.edu] and the INDEPTH Data Repository [http://www.indepth-ishare.org/index.php/catalog/113]. Mortality data are available upon request.

Perceptions of HIV acquisition risk and prevalence shape sexual behavior in sub-Saharan Africa (SSA). We used data from the Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa baseline survey. Data were collected through home-based interviews of 5059 people ≥ 40 years old. We elicited information on perceived risk of HIV acquisition and HIV prevalence among adults ≥ 15 and ≥ 50 years old. We first describe these perceptions in key subgroups and then compared them to actual estimates for this cohort. We then evaluated the relationship between sociodemographic characteristics and accurate perceptions of prevalence in regression models. Finally, we explored differences in behavioral characteristics among those who overestimated risk compared to those who underestimated or accurately estimated risk. Compared to the actual HIV acquisition risk of < 1%, respondents vastly overestimated this risk: 35% (95% CI: 32–37) and 34% (95% CI: 32–36) for men and women, respectively. Respondents overestimated HIV prevalence at 53% (95% CI: 52–53) for those ≥ 15 years old and 48% (95% CI: 48–49) for those ≥ 50 years old. True values were less than half of these estimates. There were few significant associations between demographic characteristics and accuracy. Finally, high overestimators of HIV prevalence tested themselves less for HIV compared to mild overestimators and accurate reporters. More than 30 years into the HIV epidemic, older people in a community with hyperendemic HIV in SSA vastly overestimate both HIV acquisition risk and prevalence. These misperceptions may lead to fatalism and reduced motivation for prevention efforts, possibly explaining the continued high HIV incidence in this community.