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

doi:10.1093/ije/dyad104

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

Int J Epidemiol. 2023 Dec 25;52(6):1878-1886. doi: 10.1093/ije/dyad104.

Authors

Neil M Davies^{1

2

3

4}, Matt Dickson⁵, George Davey Smith^{4

6}, Frank Windmeijer^{4

7}, Gerard J van den Berg^{8

9}

Affiliations

¹ Division of Psychiatry, University College London, London, UK.
² Department of Statistical Sciences, University College London, London, UK.
³ K.G. Jebsen Center for Genetic Epidemiology, Department of Public Health and Nursing, Norwegian University of Science and Technology, Tronheim, Norway.
⁴ Medical Research Council Integrative Epidemiology Unit, University of Bristol, Bristol, UK.
⁵ Institute for Policy Research, University of Bath, Bath, UK.
⁶ Population Health Sciences, University of Bristol, Bristol, UK.
⁷ Department of Statistics and Nuffield College, University of Oxford, Oxford, UK.
⁸ Department of Economics, University of Groningen, Groningen, The Netherlands.
⁹ Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands.

Abstract

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.

Keywords: Raising Of School Leaving Age (ROSLA); education; genomic confounding; instrumental variable analysis.

MeSH terms

Adult
Causality
Educational Status
Genome-Wide Association Study
Genotype
Humans
Mendelian Randomization Analysis* / methods
Schools*

Abstract

MeSH terms

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