Causal effects of schooling on memory at older ages in six lowand-middle-income countries : nonparametric evidence with harmonized datasets

Higher schooling attainment is associated with better cognitive function at older ages, but it remains unclear whether the relationship is causal. We estimate 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. 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 partialidentification approach that bounds causal effects of increasing schooling attainment at different parts of the schooling distributions under relatively weak assumptions. We find that an additional year of schooling, moving from none into primary school, increased word-recall scores by between 0.01-0.13 standard deviations (SDs) in China, 0.01-0.06SDs in Ghana, 0.02-0.09SDs in India, 0.02-0.12SDs in Mexico, and 0-0.07SDs in South Africa. 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. 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 five diverse low-and-middle-income countries.