Psicologia

ORIGINAL ARTICLE

Changes in Genetic and Environmental Influences on Disordered Eating Across Adolescence
A Longitudinal Twin Study
Kelly L. Klump, PhD; S. Alexandra Burt, PhD; Matt McGue, PhD; William G. Iacono, PhD

Context: Previous research suggests substantial in-

creases in genetic effects on disordered eating across adolescence. Unfortunately, these studies were crosssectional andfocused primarily on early (age 11 years) vs late (age 17 years) adolescence.
Objective: To examine longitudinal changes in ge-

sessed with the total score from the Minnesota Eating Behavior Survey.
Results: Biometric model-fitting indicated significant

netic and environmental influences on disordered eating across early, mid, and late adolescence.
Design and Setting: Population-basedstudy of fe-

changes in genetic and shared environmental effects across early to mid adolescence. Although genetic factors accounted for a negligible proportion (6%) of variance at age 11 years, genes increased in importance and accounted for roughly half of the variance (46%) in disordered eating at ages 14 and 18 years. Shared environmental influences decreased substantially across these sameages.
Conclusions: Findings highlight the transition from early to mid adolescence as a critical time for the emergence of a genetic diathesis for disordered eating. The increase in genetic effects during this developmental stage corroborates previous research implicating puberty in the genetic etiology of eating disorders.

male same-sex twins.
Participants: Seven hundred seventy-two femaleado-

lescent twins from the Minnesota Twin Family Study assessed at ages 11, 14, and 18 years.
Main Outcome Measures: Disordered eating symptoms (ie, body dissatisfaction, weight preoccupation, binge eating, and the use of compensatory behaviors) were as-

Arch Gen Psychiatry. 2007;64(12):1409-1415 We have previously examined developmental differences in genetic and environmental influences onDE using crosssectional data from the Minnesota Twin Family Study (MTFS).7,10,11 Findings were striking in suggesting substantial differences in genetic effects across development. We found essentially no genetic influence on overall levels of DE (ie, levels of body dissatisfaction, weight preoccupation, binge eating, and the use of compensatory behaviors) in 11-year-old twins but foundsignificant genetic effects ( 50%) in 17-year-old twins.7 Importantly, however, genetic influences did contribute to DE ( 50%) in 11-year-old twins who had begun puberty.10 These findings collectively imply that puberty may play a role in the genetic diathesis for DE. A subsequent study of the twins at age 14 years offered additional support for this hypothesis; results indicated that pubertal developmentmoderates genetic effects on DE (ie, genetic influences were

Author Affiliations: Department of Psychology, Michigan State University, East Lansing (Drs Klump and Burt); and Department of Psychology, University of Minnesota, Minneapolis (Drs McGue and Iacono).

past 20 years has demonstratedthatanorexianervosa (AN),1-4 bulimia nervosa (BN),5,6 and disordered eating (DE)7,8 exhibit significantgenetic effects in adults. Heritabilities tend to be greater than 50% with the remaining variance due to nonshared rather than shared environmental influences. These findings clearly underscore the importance of genetic factors for eating disorders in adulthood. However, they tell us little about genetic influences on DE during adolescence, the peak period of risk for eating disorders.9 Moreover,they ignore potential developmental changes in genetic influences that may provide important clues as to the mechanisms of genetic effects. Indeed, identifying periods during which genetic influences become prominent can inform neurobiological and molecular genetic research about the systems and genes that may contribute to the genetic diathesis of the disorders.

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