Genetic Contributions in Intelligence

An intelligence study spanning eight decades confirms that genetics partially determines how well an individual’s cognitive abilities last into old age.

Deary et al (2012) provide an estimate of the genetic and environmental contributions to stability and change in intelligence across most of the human lifetime. They used genome-wide single nucleotide polymorphism (SNP) data from 1,940 unrelated individuals whose intelligence was measured in childhood (age 11 years) and again in old age (age 65, 70 or 79 years). 

A statistical method that allows genetic (co)variance to be estimated from SNP data on unrelated individuals was used. They estimate that causal genetic variants in linkage disequilibrium with common SNPs account for 0.24 of the variation in cognitive ability change from childhood to old age. Using bivariate analysis, they estimate a genetic correlation between intelligence at age 11 years and in old age of 0.62. These estimates, derived from rarely available data on lifetime cognitive measures, warrant the search for genetic causes of cognitive stability and change.

Result showed that genetic variants accounted for approximately 25 percent of the differences in the participants’ cognitive stabilities.

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Deary, I.J., et al. (2012). Genetic contributions to stability and change in intelligence from childhood to old age. Nature January 18. DOI: 10.1038/nature10781