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Sibling study finds early education boosts brain power

How much does education actually sharpen the mind?

A study in the Journal of Human Capital may help settle this long-standing debate by comparing adult siblings in Indonesia. Led by Yuan Zhang, assistant professor of Sociomedical Sciences in the Robert N. Butler Columbia Aging Center at Columbia University Mailman School of Public Health, the research reveals education's impact on adult cognition—particularly for people from disadvantaged backgrounds.

Key findings

• Each additional year of education completed during the first nine years of schooling nearly doubled adult quantitative and abstract reasoning skills.
• Children of less-educated mothers saw a large cognitive gain from basic schooling compared to peers with more-educated mothers, but the benefits diminished at higher levels of their own education. In contrast, among children of more-educated mothers, the cognitive benefits of education were more consistent across all levels of education.
• These cognitive benefits aren't fleeting. Decades after participants left school, those with more education maintained sharper quantitative skills and abstract reasoning abilities.

"Our study demonstrates education's unique power to disrupt cycles of disadvantage," says Zhang. "This lifelong dividend underscores schooling's role not just in childhood development but in sustaining cognitive health across the adult lifespan. These results are a roadmap for reducing inequality. Early investments in universal basic education pay double dividends—stronger minds today and healthier aging tomorrow."

Sibling study

The team analyzed over 20 years of data from Indonesian families with a remarkably high recontact rate. By comparing brothers and sisters—who share genetics, parents, and childhood environments—researchers isolated education's unique effects on quantitative and abstract reasoning separate from family background factors common to siblings.

"Imagine two siblings raised together," explains Zhang. "If one sister completes high school while her sister only finishes primary school, any cognitive differences between them in adulthood are likely due to those extra years of education—not family background."

To validate this approach, researchers conducted a placebo-type test using height, which schooling doesn't affect. While education initially appeared linked to height when comparing individuals among those studied, this connection vanished when comparing siblings—confirming their method's rigor.

Additional co-authors of the paper, titled "Education and Adult Cognition in a Low-Income Setting: Differences among Adult Siblings," include Elizabeth Frankenberg, University of North Carolina at Chapel Hill; and Duncan Thomas, Duke University.