Using HAALSI data, this study will determine how cumulative, randomized, and quasi-randomized socioeconomic exposures in mid-to-later-life affect memory decline and ADRD risk in later-life, by linking three unique population data sources in South Africa that cover a 22-year period (2000 to 2021). These contributions will provide robust evidence on ADRD etiology and will serve as sentinel findings for prevention strategies not only in sub-Saharan Africa, where there is currently little data outside of this study, but also for guiding interventions in ADRD prevention programs globally.