Abstract

Behavior and Genetic: Confounding Effects on Adolescent Body Mass Index

Author(s): Molly Jacobs

Introduction: Persistently high rates of obesity have made understanding the determinants of BMI a research priority. However, the relationship between genetic disposition and behavior remains unclear. This study examines the relationship between genetic risk for body mass index (BMI) and health-related behaviors. Results show that sleep, exercise, screen time, school enrollment and disordered eating mediate heritable genetic influences.
Methods: Using a longitudinal panel, analysis tests the strength of the genetic influence on BMI controlling for demographic attributes and ancestry-specific principle components. Multilevel structural equation models evaluate the mediating/moderating influences of behavior on genetic conditioning.
Results: Sleep, exercise, and school enrollment are associated with lower BMI, while screen time, disordered eating, and age are associated with higher BMI. Polygenic risk score has the largest BMI impact. Behavior not only has a direct BMI impact, but also a mediating influence. Sleep, school enrollment, exercise and reduced screen time serve as partial mediators in the BMI-PGS relationship.
Conclusions: Mediation analysis shows that not only do these behaviors have a direct effect on BMI; they also serve as partial mediators to BMI polygenic risk scores. Sleep, school enrollment, exercise and reduced screen time serve as partial mediators, in the path from polygenic risk score to BMI by reducing the magnitude of the genetic effect on BMI. This suggests that behavioral modifications could be used to offset genetically-influenced weight increases. PDF