Keywords: ADHD; Polygenic scores; Educational attainment
Authors: E. Stergiakouli1, J. Martin2, M. L. Hamshere2, A. Thapar2, D. M. Evans1, N. J. Timpson1, G. Davey Smith1; 1MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, United Kingdom, 2MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University School of Medicine, Cardiff, United Kingdom.
High levels of ADHD symptoms during childhood carry risk of worse academic performance and can impact on employment and earnings in adulthood. Polygenic score analysis was used to show that common risk alleles for clinical ADHD contribute to the risk of having higher ADHD symptoms in the general population (Martin et al. in press). We have used polygenic score analysis to investigate the contribution of common risk variants for clinical ADHD on educational performance and IQ in the general population.
Academic performance was assessed using results from Key Stage 3 national tests and externally marked GCSE examinations in 6,385 children from the Avon Longitudinal Study of Parents and Children (ALSPAC). Polygenic risk scores were calculated for ALSPAC children and their mothers based on the results of an ADHD GWAS (Stergiakouli et al. 2012).
ADHD polygenic scores on the children were associated with worst educational outcomes as represented by both time points and also with lower IQ scores at age 15.5 (see Table). Moreover, ADHD polygenic scores on the mothers were associated with lower IQ in the mothers and worst educational outcomes in the children (see Table).
Our results suggest that the same genetic variants that are relevant for an ADHD diagnosis are also implicated in impaired academic performance in the general population and lower IQ score in both children and adults.