Date of Award

Spring 1-1-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology & Neuroscience

First Advisor

Michael C. Stallings

Second Advisor

John K. Hewitt

Third Advisor

Kelly L. Klump

Abstract

Prior studies have shown that eating disorders and disordered eating characteristics have similar contributions of genetic and environmental influences. However, few studies have identified specific genetic variants that influence these phenotypes. It is possible that the lack of replication studies is due to the focus on one particular polymorphism rather than a more comprehensive approach that includes multiple polymorphisms at a given locus. In addition, little information is known about common risk factors for eating disorders and co-occurring traits, such as substance use and personality. This dissertation uses adolescent and young adult twins and their family members from the community sample of the Colorado Center for Antisocial Drug Dependence (CADD) to investigate risk factors for disordered eating, substance use, and specific personality traits. Findings from the research examining risk factors for disordered eating provide insight into whether putative genetic variants, such as those in the serotonin transporter gene (SLC6A4), are associated with these characteristics. First, extended twin analyses were used to investigate genetic and environmental influences on two disordered eating characteristics identified from the CADD. Second, a family-based association test examined whether specific genetic variants in and near SLC6A4 were associated with disordered eating. Finally, phenotypic correlations among disordered eating, substance use, and personality traits were examined. Results from the first study suggested that individual differences in disordered eating characteristics could be explained by additive genetic and non-shared environmental influences. Findings from the second study suggested that a genetic variant upstream of the 5' region of SLC6A4 was associated with a measure of weight and shape concerns and behaviors, even after controlling for multiple genetic variant testing. The final study found small phenotypic correlations between disordered eating and multiple substance use measures, and between disordered eating and specific personality traits. Implications for these findings are discussed.

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