Genetic mediation in the relationship of education to cognitive function in older people.

We used data from 136 monozygotic and 125 dizygotic human, male twin pairs (M age = 64 years, range = 59 to 70 years) to test whether the previously observed association (r = .30, p < .01) between cognitive performance and education in this sample is genetically mediated. Biometric genetic modeling found that a common genetic latent variable accounted for 44% of the total variance in the Mini-Mental State Exam (MMSE: M. F. Folstein, S. E. Folstein, & P. R. McHugh, 1975), 40% of the variance in the Iowa Screening Battery for Mental Decline (P. J. Eslinger, A. R. Damasio, & A. L. Benton, 1984), and 21% of the variance in educational attainment. In addition, specific genetic and environmental variables contributed significantly to individual differences in education and cognitive performance of the participants.