The Harvard Center for Population and Development Studies, in partnership with the MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt) of the University of the Witwatersrand, and SALDRU, were recently granted funding from the United States’ National Institute on Aging (NIA) for a 5-year extension of The Health and Aging in Africa: A Longitudinal Study in South Africa (HAALSI). This program comprises several work streams and includes data collection on two sub-populations: two further rounds of an existing longitudinal study on health and aging in Agincourt; and the first round of a new national South African longitudinal sister study on health and aging, whose implementation will be led by SALDRU. This new national study will be the first national study of its kind in Africa.
The importance of the program
Like many low- and middle-income countries (LMICs), South Africa has experienced complex demographic and epidemiologic transitions in the last few decades, with uneven declines in mortality related to both infectious diseases (primarily HIV-related) and non-communicable diseases. Adults in South Africa are surviving to older ages, yet the burden and risk factors of aging-related diseases, particularly dementia and Alzheimer’s disease, remains poorly defined in general.
By 2050, the majority of global dementia cases are projected to occur in LMICs; however, little is known about the biological, social, and economic factors that shape patterns of dementia risk or resilience in these populations, since most evidence comes from high-income countries.
Building on an existing body of work
In 2013, The Harvard Center for Population and Development Studies, in partnership with the MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt) were awarded a grant from the NIA to study the drivers and consequences of HIV and non-communicable diseases in an aging population in the Agincourt health and socio-demographic surveillance system (HDSS) study area. The Agincourt HDSS is a node of the South African Population Research Infrastructure Network (SAPRIN), and is situated in Mpumalanga, close to the border with Mozambique. In 2014–2015, a first wave of interview and biomarker data were collected from a sample of men and women aged 40 and older in Agincourt. Two additional waves of data collection took place in 2018 and 2021, under a 2017 grant renewal.
The 2023 grant renewal involves a major expansion of the project with a focus on dementia and cognitive decline, alongside the major diseases and disorders (cardiometabolic disease and HIV) that impact cognitive function and their relationships to aging and socio-economic status. A 4th and 5th survey wave of the community-representative Agincourt cohort will be funded. In addition, this grant will support the introduction of a similar nationally representative longitudinal survey across South Africa, and a pilot of the extension of the survey to additional communities in SAPRIN, both urban and rural. This national study will be a sister study to the Agincourt HAALSI study, and its implementation will be led by SALDRU.
The national study will enable the estimation of the prevalence of dementia and other aging-related conditions, and their associations with socioeconomic, behavioural, and health utilization exposures. The program team also aims to use innovative comparative methods to assess the alignment of diseases in the rural Agincourt HAALSI community with the national level.
The studies’ design is finely tuned to capture characteristics specific to the aging process in South Africa, as well as to harmonize with the Health and Retirement Study (HRS) and sister studies in India, China, Brazil, Europe, and the United States. The South African national study will join these studies as the first national HRS sister study in Africa. Both the Agincourt and national surveys include an in-depth cognitive assessment on a sub-sample of participants using the Harmonized Cognitive Assessment Protocol (HCAP). In this way, the project data will provide a unique opportunity to compare the biological, social, and economic determinants of chronic diseases and dementia, and their effects on functional and health outcomes in aging populations in South Africa.
Collaborators on the program
The HAALSI Agincourt and national sister study program is led by an interdisciplinary team of collaborators from the following institutions:
- Harvard T.H. Chan School of Public Health
- University of Witwatersrand
- University of Cape Town
- The INDEPTH Network, a global network of health and demographic surveillance systems based in Ghana
- Columbia University Department of Neurology
The broader program team is currently preparing for the fourth round of data collection of the HAALSI Agincourt study, which is due to take place in 2024.
While data collection for the national study is only due to take place in a few years’ time, the team has begun engaging with stakeholders and has started work towards planning the national study.
The new program will be formally launched, with relevant stakeholders, in February 2024.