The causal effects of education on adult health, mortality and income: Evidence from Mendelian randomization and the raising of the school leaving age

Neil M. Davies*, Matt Dickson, George Davey Smith, Frank Windmeijer, Gerard J. Van Den Berg

*Corresponding author for this work

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Background: On average, educated people are healthier, wealthier and have higher life expectancy than those with less education. Numerous studies have attempted to determine whether education causes differences in later health outcomes or whether another factor ultimately causes differences in education and subsequent outcomes. Previous studies have used a range of natural experiments to provide causal evidence. Here we compare two natural experiments: A policy reform, raising the school leaving age in the UK in 1972; and Mendelian randomization. Methods: We used data from 334-974 participants of the UK Biobank, sampled between 2006 and 2010. We estimated the effect of an additional year of education on 25 outcomes, including mortality, measures of morbidity and health, ageing and income, using multivariable adjustment, the policy reform and Mendelian randomization. We used a range of sensitivity analyses and specification tests to assess the plausibility of each method's assumptions. Results: The three different estimates of the effects of educational attainment were largely consistent in direction for diabetes, stroke and heart attack, mortality, smoking, income, grip strength, height, body mass index (BMI), intelligence, alcohol consumption and sedentary behaviour. However, there was evidence that education reduced rates of moderate exercise and increased alcohol consumption. Our sensitivity analyses suggest that confounding by genotypic or phenotypic confounders or specific forms of pleiotropy are unlikely to explain our results. Conclusions: Previous studies have suggested that the differences in outcomes associated with education may be due to confounding. However, the two independent sources of exogenous variation we exploit largely imply consistent causal effects of education on outcomes later in life.

Original languageEnglish
Pages (from-to)1878-1886
Number of pages9
JournalInternational Journal of Epidemiology
Issue number6
Publication statusPublished - Dec-2023


  • education
  • genomic confounding
  • instrumental variable analysis
  • Raising Of School Leaving Age (ROSLA)

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