PROJECT SUMMARY
By 2050, 75% of Alzheimer’s disease and related dementias (ADRD) cases will occur in low- and middle-income
regions, like rural South Africa, which are severely under-represented in ADRD research. There is a critical
evidence gap on the role of socioeconomic status (SES) in ADRD etiology in low-income settings, and how SES
can best be targeted by interventions to prevent and/or delay ADRD onset. Our long-term goal is to inform the
design of gender-equitable SES interventions to prevent and/or delay ADRD onset in low-income settings. The
objective of this proposal is to identify how SES affects ADRD risk, using longitudinal exposures (household
assets, food security, and employment) and randomized and quasi-randomized cash transfer exposures
accumulated over time in mid-to-later-life in rural South Africa. Our central hypothesis is that greater cumulative
exposure to advantageous socioeconomic conditions will protect against ADRD, with differential effects for men
and women for household-level SES resources that may not be equally allocated between genders. To test this
central hypothesis, we will leverage a unique opportunity to create one of the first longitudinal data platforms to
study ADRD risk in Africa: we will link high-quality memory and ADRD outcome data collected from 2015-21 in
the population-representative “Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in
South Africa” (HAALSI; N=5059) to detailed SES exposure data collected since 2000 in the “Agincourt Health
and Sociodemographic Surveillance System” (AHDSS; a census with 100% population coverage) and the HPTN
068 randomized controlled trial of cash transfers to households from 2011-15 (N=863 households in both HPTN
068 and HAALSI). These three datasets can be linked because the AHDSS census is the sampling frame for
HAALSI and HPTN 068; we have confirmed linkage feasibility in our preliminary data. Specifically, we aim to: 1)
Determine the roles of mid-to-later life cumulative household assets, employment, and food security (2000-13;
AHDSS) in memory decline and ADRD risk (2015-21; HAALSI); 2) Determine whether exposure to cash transfer
interventions affect memory decline and ADRD by leveraging 2a) randomized cash transfers in HPTN 068; 2b)
expansion of the South African Old Age Pension for men; 2c) expansion of the South African Child Support Grant
for mothers; and 3) Determine how gender modifies the effects of household-level SES exposures in Aims 1 &
2a. This proposal is innovative because the study population of older, rural Black South African adults improves
representation of understudied groups in ADRD research; our longitudinal assessments of SES exposures over
14 years improve upon the status quo of SES measured retrospectively or at single points in time; and our
linkage of the HAALSI cohort to a randomized controlled cash transfer trial and data on national social protection
policies allows causal inference about income and ADRD risk. This proposal is a major opportunity for life course
research in a rapidly aging, low-income population that can provide insights into ADRD etiology and strategies
to prevent and/or delay ADRD onset in global low-income settings, where there is little data outside this study.
