INTELLIGENCE AND EDUCATION AS PREDICTORS OF COGNITIVE STATE IN LATE-LIFE - A 50-YEAR FOLLOW-UP

We evaluated the relation of education and intelligence in early adult life to cognitive function in a group of elderly male twins. The Army General Classification Test (AGCT) was administered to US armed force s inductees in the early 1940s. Fifty years later, as part of a study of dementia in twins, we tested the cognitive status of 930 of these m en using the modified Telephone Interview for Cognitive Status (TICS-m ). TICS-m scores obtained in later Life were correlated with AGCT scor es (r = 0.457) and with years of education (r = 0.408). Thus, in univa riate analyses, the AGCT score accounted for 20.6% and education accou nted for 16.7% of variance in cognitive status. However, these two eff ects mere not fully independent. A multivariable model using AGCT scor e, education, and the interaction of the two variables as predictors o f the TICS-m score explained 24.8% of the variance, a slightly but sig nificantly greater proportion than was explained by either factor alon e. In a separate analysis based on 604 pairs of twins who took the AGC T, heritability of intelligence (estimated by AGCT score) was 0.503. A lthough this study does not address the issue of education and premorb id IQ as risk factors for dementia, the findings suggest that basic co gnitive abilities in late life are related to cognitive performance me asures from early adult life tie, education and IQ).