Monthly cash payments of approximately $20 preserved cognitive function and reduced dementia risk among adults aged 40-79 in rural South Africa, according to longitudinal research tracking participants over multiple years. The intervention showed measurable improvements in memory tasks and delayed onset of cognitive impairment compared to control groups. This finding adds compelling evidence to the growing body of research linking financial security with brain health throughout aging. Chronic economic stress triggers sustained cortisol release and inflammatory cascades that accelerate neurodegeneration, particularly in regions critical for memory formation. The South African results align with similar cognitive benefits observed in Finland's universal basic income trials and Kenya's GiveDirectly programs, suggesting that alleviating financial anxiety may be a surprisingly effective neuroprotective strategy. The mechanism likely involves reduced chronic stress, improved nutrition access, and enhanced social engagement when basic needs are met. For aging populations worldwide, these findings suggest that addressing economic insecurity could complement traditional dementia prevention approaches like exercise and cognitive training. However, the study's focus on rural populations with limited healthcare access may limit generalizability to developed nations where baseline cognitive decline rates and stressors differ substantially.