Genetic instrumental-variable analysis supports a causal negative effect of higher BMI in childhood and adolescence on GCSE attainment and school absence (ALSPAC cohort)¶

Claim · All claims
Evidence · 1 study · causal r2 · q3
Currency · newest study 2021 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i? Using the BMI polygenic score as an instrument, each unit increase in BMI z-score at 10 predicted 16.79 lower GCSE points and 8.73% greater absence; estimates were similar for BMI at 13. → Hughes 2021

Evidence¶

Hughes 2021¶

Hughes, A., Wade, K. H., Dickson, M., Rice, F., Davies, A., Davies, N. M. & Howe, L. D. (2021). Common health conditions in childhood and adolescence, school absence, and educational attainment: Mendelian randomization study. npj Science of Learning 6:1. https://doi.org/10.1038/s41539-020-00080-6

q3 · i? · causal · r2

One-sample Mendelian randomization in ALSPAC (N=6113), the only PGS strong enough to be an instrumental variable. The article states "GCSE points scores were 16.79 lower" per unit BMI z-score, with absences 8.73% greater; no standardised effect size is printed for this IV estimate.

"Using the BMI PGS as an instrumental variable showed that, for each unit increase in BMI z-score at age 10, GCSE points scores were 16.79 lower (95% CI: −24.38, −9.19) and absences were 8.73% greater (95% CI: 1.82, 16.12)."

Discussion¶

Related Claims¶

• In multivariate-adjusted phenotypic models, all measured child/adolescent health conditions except migraine and asthma are associated with poorer GCSE attainment at 16 (ALSPAC cohort) — related
• School absence mediates health–attainment associations, least for ADHD (7.1%) and most for migraine (72.0%) and BMI (39.9%) (ALSPAC cohort) — related
• Two-sample Mendelian randomization in independent adult samples supports negative effects of BMI (and, secondarily, asthma) on years of schooling, with little evidence for migraine — related
• Genetic liability for ADHD predicts lower GCSE attainment but not greater school absence (ALSPAC cohort) — related
• All measured health conditions are associated with greater school absence at 14–16, and depressive symptoms at 10 show a considerably stronger association with GCSEs than at 13 (ALSPAC cohort) — related
• After controlling for selection factors and EduYears GPS, genetic differences between school types disappear and school type explains less than 1% of GCSE variance (down from 7%) — related