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Pioneering tests could improve the assessment of dementia in ageing Africans

1 April 2025 - Wits University

International researchers have introduced two improved tests that could precisely detect cognitive dysfunction in older African adults. 

These new tools, part of a comprehensive set of 29 assessments, improve upon conventional dementia evaluations commonly used in developed regions. 

Experts say the initiative will fill critical gaps in global ageing studies, offering vital insights into dementia prevalence and cognitive health in underrepresented populations.

Dementia rates expected to rise in Africa

Sub-Saharan Africa is projected to have a dramatic rise in dementia prevalence by 2050 owing to an increasing ageing population. In South Africa, in particular, more than one million people could be living with dementia in the upcoming decades, solidifying what is known about the significant community, social, and economic impact of dementia in rural areas.

Specialised tests tailored for the South African context

The highly specialised tests tailored for the South African context will show additional neuropsychological, functional, and biomarker indicators to measure dementia in already cognitively impaired study participants. 

Thus, the extent to which dementia has progressed in people participating in a longitudinal study may be revealed.

Linking African studies to a global research network

In a bid to add to a global network of ageing studies (including the US Health and Retirement Study – HRS), these new, specialised tests form part of the HAALSI Dementia-Harmonised Cognitive Assessment Protocol (HAALSI-HCAP) study, which is nested in the larger HAALSI programme. 

(The more considerable HAALSI study looks at numerous ageing concerns, including cardiometabolic diseases and HIV. HAALSI is Heath and Ageing in Africa Longitudinal Studies).

The urgency for dementia research in Africa

“By 2050, more than 70% of people living with dementia will reside in low-income and middle-income countries – but we have seriously sparse information, on a population level, about the true prevalence of dementia,” says Professor  Director of the SA Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (). 

Agincourt, where the primary research occurs, is a globally significant health and socio-demographic surveillance site in Mpumalanga, in rural northeast South Africa. It comprises 31 villages and about 120,000 people.

Advanced-data collection tools to improve dementia testing

The HAALSI-HCAP sub-study uses advanced research collection techniques, including data-driven algorithms, to improve the precision of the study’s measurements.

Senior research analyst for the HAALSI-HCAP study, Dr Tamara Taporoski, based at the Harvard Center for Development and Population Studies, notes that “although algorithmic estimation of dementia prevalence is widely used in the USA and other high-income countries, HAALSI is the first to blend expert diagnoses with such predictive algorithms. This pioneering approach is a game-changer for regions with limited healthcare resources, where traditional large-scale testing is often impractical due to funding shortages, lack of specialists, and weak infrastructure.”

Understanding dementia risk factors in Africa

Better testing can reveal what causes dementia in Africans and what to do about it. 
Risk factors for dementia include limited educational opportunities, a decline in sensory functions (such as sight or hearing), and poorly controlled cardiovascular health. These are common in the Agincourt study area.

“To minimise or prevent dementia, we need to build ‘cognitive reserve’ – meaningful social connections, being exposed to new experiences, and a solid education throughout life are important,” says Harvard Senior Analyst Dr Paul Kojo Ayernor. 
Ayernor is responsible for managing Agincourt study operations and performing data analysis for the HAALSI Agincourt surveys.

The problem of inconsistent testing methods

Dementia rates in sub-Saharan Africa differ widely, mainly due to inconsistent study methods. There is a lack of standardised and validated data. Expert diagnosis is the most accurate, but it requires significant resources, making it difficult to use on a large scale.

“Fortunately, we have access to the best science. HAALSI, as a population-based study, incorporates longitudinal measurements of cognition and everyday functions to characterise the burden of dementia in sub-Saharan Africa. Excellent testing methods now complement this extensive data. We can harmonise data and, broadly, dementia testing globally,” says Taporoski.

Aligning African research with global efforts

In other words, the study is uniquely designed to capture the nuances of ageing in South Africa while seamlessly aligning with global research efforts, including the US’s HRS and sister studies in India, China, Brazil, and Europe.

Tollman adds that the HAALSI-HCAP study may lead to a national survey across South Africa. “This means we can build a virtually non-existent evidence base. Our efforts could provide a foundation to expand our understanding of dementia epidemiology in a region of the world experiencing rapid population ageing.”

Future steps for the HAALSI-HCAP study

The HAALSI-HCAP is now in its third wave and the new battery of tests were piloted in March. The larger HAALSI study follows 4,500 individuals over 40 years of age. HCAP is then administered to a small group of 680 individuals with signs of cognitive decline. The entire study is nationally representative.

“What is really exciting is that we can get more granular data. We can dig deeper and see how cardiometabolic diseases and HIV interact with dementia,” says Toporoski.

An interdisciplinary team of collaborators leads the study from the following institutions:

•    Harvard T.H. Chan School of Public Health
•    University of the Witwatersrand, Johannesburg (MRC/Wits-Agincourt)
•    University of Cape Town
•    The  Network, a global network of health and demographic surveillance systems, based in Ghana
•    Columbia University, Department of Neurology