GENETIC INFLUENCES ON MEMORY PERFORMANCE IN ADULTHOOD - COMPARISON OFMINNESOTA AND SWEDISH TWIN DATA

Results from 2 twin studies of aging differ concerning the heritabilit y of memory performance in adulthood. Heritability estimates from the Minnesota Twin Study of Adult Development and Aging (MTSADA; D. Finkel & M. McGue, 1993) are larger than estimates from the Swedish data (N. L. Pedersen, R. Plomin, J. R. Nesselroade, & G. E. McClearn, 1992). M emory data were available from MTSADA on a sample of 112 monozygotic ( MZ) twin pairs and 111 dizygotic (DZ) twin pairs ages 27 to 88 years a nd from the Swedish study on a sample of 86 MZ and 110 DZ twin pairs w ho were reared together and were ages 27 to 85 years. Univariate and m ultivariate behavior genetic analyses were conducted to determine the significance and source of differences in heritability across studies. No significant age differences were found in either study. Study diff erences were found at the level of specific memory measures, but not a t the level of a general memory factor.