An international team of researchers has identified 74 areas of the human genome associated with educational attainment. It is well known that social and other environmental factors influence education, but these findings, reported by the Social Science Genetics Association Consortium (SSGAC) and supported in part by the National Institutes of Health, suggest that large genetics analyses may be able to help discover biological pathways as well.
The genome-wide association study (GWAS) was supported by the National Institute on Aging (NIA) and the Office of Behavioral and Social Sciences Research, both part of NIH, and appears in the May 11, 2016, issue of Nature.
"This is an interesting development in behavior genetics," said NIA Director Richard J. Hodes, M.D. "It extends our understanding of the connection between the genetic components of cognition and years of formal education."
The SSGAC, led by Daniel J. Benjamin, Ph.D., of the University of Southern California, found 74 separate areas (loci) on human chromosomes that are associated with more years of education. These loci are also associated with other areas that correlate with increased cognitive performance and intracranial volume, decreased levels of emotional instability (neuroticism) and decreased risk of Alzheimer's disease.
The researchers conducted the GWAS on almost 294,000 people, of primarily European descent, from research across the globe. Genetic samples were obtained from several ongoing studies, including many funded by NIA: the Health and Retirement Study, the Age, Gene/Environment Susceptibility Reykjavic Study, and the SardiNIA Study of Aging, as well as dozens of other cohorts. Crucially, the team then replicated these findings in an independent sample of more than 111,000 people from the UK BioBank study.
Previous research has shown that genetic factors account for about 20 percent of variation in educational attainment. In this study, 74 single nucleotide polymorphisms (SNPs) were identified. The investigators note that, as a group, these SNPs only account for a very small portion (0.43 percent) of the variation across individuals in the sample; individually, each SNP has a very small influence.
The study team regards this study as preliminary and exploratory. Because educational attainment is a complex phenomenon, there are many additional sources of molecular genetic variation to be discovered. Other genetic and environmental effects and their interactions are important topics for future research.
"These study results will enable us to ask more refined questions about the genetic and environmental underpinnings of educational attainment and their health consequences," said Jonathan W. King, Ph.D., program director in NIA's Division of Behavioral and Social Research, which supports the SSGAC. "For example, we've known for quite a while that education appears to be a protective factor against Alzheimer's. But, education is itself a very complicated outcome. It depends on genetic contributions to cognitive ability and other characteristics that motivate individuals to continue education, as well as substantial environmental contributions to educational success.
"The results of this study and future work will enable us to better understand how these pathways interact," King continued. "Perhaps ultimately, we'll be able to learn why and how educational attainment seems to be protective of cognition in later life."
The size of the study made it possible to answer questions not able to be addressed previously. For example, the researchers were able to identify many more loci that appear to contribute to cognitive ability than had been previously known because of the large number of participants.
The study has implications for future research, where these links can be further explored. Data on the level of education attained by participants is routinely collected. With that information and a DNA sample, investigators can conduct additional GWAS of other racial and ethnic groups, which could allow identification of new variants and genetic pathways associated with educational attainment and further validate the contribution of loci from the study reported today.
The research was coordinated by SSGAC. Funded by the NIA, the SSGAC is a cooperative enterprise among biomedical researchers and social scientists that coordinates genetic association studies for social science outcomes and provides a platform for interdisciplinary collaboration.