Immediate Communication

Molecular Psychiatry (2011) 16, 996–1005; doi:10.1038/mp.2011.85; published online 9 August 2011

Genome-wide association studies establish that human intelligence is highly heritable and polygenic

G Davies1, A Tenesa2,3, A Payton4, J Yang5, S E Harris6,7, D Liewald1,7, X Ke8, S Le Hellard9, A Christoforou9, M Luciano1,7, K McGhee1, L Lopez1,7, A J Gow1,7, J Corley1, P Redmond1, H C Fox10, P Haggarty11, L J Whalley10, G McNeill10, M E Goddard12,13, T Espeseth14, A J Lundervold15, I Reinvang14, A Pickles16, V M Steen9,17, W Ollier4, D J Porteous6,7, M Horan18, J M Starr7,19, N Pendleton18, P M Visscher5,7,20 and I J Deary1,7,20

  1. 1Department of Psychology, University of Edinburgh, Edinburgh, UK
  2. 2Institute of Genetics and Molecular Medicine, MRC Human Genetics Unit, Western General Hospital, University of Edinburgh, Edinburgh, UK
  3. 3The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, UK
  4. 4Centre for Integrated Genomic Medical Research, University of Manchester, Manchester, UK
  5. 5Queensland Institute of Medical Research, Brisbane, QLD, Australia
  6. 6Medical Genetics Section, University of Edinburgh Molecular Medicine Centre, Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, UK
  7. 7Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
  8. 8Institute of Child Health, University College London, London, UK
  9. 9Dr Einar Martens Research Group for Biological Psychiatry, Department of Clinical Medicine, University of Bergen, Bergen, Norway
  10. 10Institute of Applied Health Sciences, University of Aberdeen, Aberdeen, UK
  11. 11Nutrition and Epigenetics Group, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
  12. 12Department of Food and Agricultural Systems, University of Melbourne, Parkville, VIC, Australia
  13. 13Biosciences Research Division, Department of Primary Industries, Bundoora, VIC, Australia
  14. 14Department of Psychology, Center for the Study of Human Cognition, University of Oslo, Oslo, Norway
  15. 15Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
  16. 16Department of Medicine, School of Epidemiology and Health Science, University of Manchester, Manchester, UK
  17. 17Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
  18. 18School of Community-Based Medicine, Neurodegeneration Research Group, University of Manchester, Salford Royal NHS Foundation Trust, Salford, UK
  19. 19Geriatric Medicine Unit, University of Edinburgh, Royal Victoria Hospital, Edinburgh, UK

Correspondence: Dr PM Visscher (regarding statistical methods) or Dr IJ Deary (regarding phenotypes, cohorts and materials), Department of Psychology, University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh EH8 9JZ, Scotland, UK. E-mail: peter.visscher@qimr.edu.au or ian.deary@ed.ac.uk

20These authors contributed equally to this work.

Received 19 January 2011; Revised 17 May 2011; Accepted 13 June 2011; Published online 9 August 2011.

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Abstract

General intelligence is an important human quantitative trait that accounts for much of the variation in diverse cognitive abilities. Individual differences in intelligence are strongly associated with many important life outcomes, including educational and occupational attainments, income, health and lifespan. Data from twin and family studies are consistent with a high heritability of intelligence, but this inference has been controversial. We conducted a genome-wide analysis of 3511 unrelated adults with data on 549692 single nucleotide polymorphisms (SNPs) and detailed phenotypes on cognitive traits. We estimate that 40% of the variation in crystallized-type intelligence and 51% of the variation in fluid-type intelligence between individuals is accounted for by linkage disequilibrium between genotyped common SNP markers and unknown causal variants. These estimates provide lower bounds for the narrow-sense heritability of the traits. We partitioned genetic variation on individual chromosomes and found that, on average, longer chromosomes explain more variation. Finally, using just SNP data we predicted ~1% of the variance of crystallized and fluid cognitive phenotypes in an independent sample (P=0.009 and 0.028, respectively). Our results unequivocally confirm that a substantial proportion of individual differences in human intelligence is due to genetic variation, and are consistent with many genes of small effects underlying the additive genetic influences on intelligence.

Keywords:

genetics; GWAS; intelligence; quantitative trait