HERITABILITY OF COGNITIVE-ABILITIES IN ADULT TWINS - COMPARISON OF MINNESOTA AND SWEDISH DATA

Cross-sectional reports suggest heritability of cognitive ability incr eases throughout adulthood. To investigate this hypothesis, quantitati ve genetic analyses were conducted on four measures of cognitive abili ty (verbal, spatial, perceptual speed, memory). Data from Minnesota an d Swedish twin studies of aging were compared. Heritability estimates and the factor structure of cognitive abilities could be equated acros s younger twins (age, 27-50) and middle-aged twins (age, 50-65) from b oth studies, suggesting stability of heritability during adulthood. Th e heritability of 81% for a general cognitive factor confirmed earlier findings of high heritability in younger and middle-aged samples. Old er Swedish twins (age, 65-85) demonstrated significantly lower heritab ility estimates for cognitive abilities (54%) and a significantly diff erent factor structure of cognitive ability.