Grant Title: Neighborhood and genetic influences on alcohol misuse in a sample of twins
Principal Investigator: Isaac Rhew, PhD, MPH
Sponsor: University of Washington Royalty Research Fund
Project Period: 7/1/15-6/30/16
Grant Number: A101837

The goal of this research is to understand how neighborhood environments and genetic factors jointly influence risk for alcohol misuse. Greater insight into macro-environmental factors such as those occurring at the neighborhood-level could lead to ecologic prevention strategies with the potential for substantial population-level impact. While some evidence has emerged suggesting effects of neighborhood factors such as socioeconomic deprivation and alcohol outlet density on alcohol misuse, inference remains hindered because of challenges in accounting for “structural” confounding due to self-selection into neighborhoods. Further, as it has become recognized that genetic factors contribute significantly to alcohol misuse, it will be important to understand the particular environments where genetic susceptibility is greatest. Evidence for gene x environment interactions has increased, but little is known about how neighborhood-level environments modify genetic susceptibility to alcohol misuse. Such discoveries will advance our knowledge of the etiology of alcohol misuse and potentially guide neighborhood-level prevention strategies and identification of high-risk individuals. For this study, we capitalize on existing data from a community sample of approximately 4,000 adult twin pairs. The first aim of the study is to examine our hypothesis that alcohol misuse is associated with higher neighborhood deprivation and higher alcohol outlet density independent of individual-level socio-demographic characteristics. Using the co-twin design, we can address this question in an innovative way that allows us to control for genetic and shared environmental factors and thus reduce threats to validity from structural confounding. The unique characteristics of twin data will also allow us to conduct our second aim: to examine the relative contributions of additive genetic, shared environmental and unique environmental factors to alcohol misuse, and to examine whether genetic heritability will be stronger in neighborhoods with greater deprivation and higher alcohol outlet density.