Causal Effects of Schooling on Memory at Older Ages in Six Low- and Middle-Income Countries: Nonparametric Evidence With Harmonized Datasets.

Objectives: Higher schooling attainment is associated with better cognitive function at older ages, but it remains unclear whether the relationship is causal. We estimated causal effects of schooling on performances on the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) word-recall (memory) test at older ages in China, Ghana, India, Mexico, Russia, and South Africa.

Methods: We used harmonized data (n = 30,896) on older adults (≥50 years) from the World Health Organization Study on Global Ageing and Adult Health. We applied an established nonparametric partial identification approach that bounds causal effects of increasing schooling attainment at different parts of the schooling distributions under relatively weak assumptions.

Results: An additional year of schooling increased word-recall scores by between 0.01 and 0.13 SDs in China, 0.01 and 0.06 SDs in Ghana, 0.02 and 0.09 SDs in India, 0.02 and 0.12 SDs in Mexico, and 0 and 0.07 SDs in South Africa when increasing schooling from never attended to primary. No results were obtained for Russia at this margin due to the low proportion of older adults with primary schooling or lower. At higher parts of the schooling distributions (e.g., high school or university completion), the bounds cannot statistically reject null effects.

Discussion: Our results indicate that increasing schooling from never attended to primary had long-lasting effects on memory decades later in life for older adults in 5 diverse low- and middle-income countries.