GENETIC AND ENVIRONMENTAL-INFLUENCES ON FUNCTIONAL AGE - A TWIN STUDY

Twin analyses were conducted to determine the relative influence of ge netic and environmental factors on functional aging. As part of the on going Minnesota Twin Study of Adult Development and Aging (MTSADA), me asures of 30 demographic, cognitive, physiological, personality, and b ehavioral variables were available from 140 monozygotic twin pairs and 97 dizygotic twin pairs ranging in age from 27 to 88 years. Functiona l age was based on a general linear regression model with chronologica l age as the dependent variable. Stepwise regression determined the su bset of variables by MTSADA providing the best prediction of chronolog ical age. Factor analysis of these 12 variables resulted in three fact ors: physiological measures, cognitive abilities, and processing speed . When entered into, a regression equation, the three factors accounte d for 66% of the variance in chronological age. Analysis of twin simil arity for components of functional age suggested the relative influenc e of genetic and environmental factors varies greatly for different co mponents of functional aging. In addition, the genetic and shared envi ronmental influences on the three components were common to all three, while the nonshared environmental influences were specific to each co mponent.