Mapping the Social Environment: Assessing Environmental Predictors in Gene-Environment Research On Addiction

Introduction. There has been increased interest in integrating genetic and environmental data to better understand gene-environment interplay in the development of addiction and related outcomes.  However, in most G-E studies to date, the environment component has consistently been represented simplistically. Much has been learned in prevention science about the environmental factors influencing substance use and related outcomes that can inform this effort. The last 20 years of etiological research on addiction has identified important risk and protective factors in the family, school, peer, and neighborhood domains. However, one of the big challenges in this endeavor is to determine how to summarize environmental influence sufficiently to capture what has been leaned in developmental studies of health behavior, but simply enough to be of use in more complex G-E models.

Method.  The approach taken summarizes environmental contributions to addiction into eight measures:  4 domains (family, peer, school, neighborhood) x 2 dimensions (general functioning & drug specific characteristics). The study consists of two parts. We first organize the items from the 32 scales of the Communities that Care (CTC) youth survey into these 8 measures, and create the scales using the publicly available CTC Normative Database consisting of over 320,000 youth respondents assessed from 2000 to 2002. Reliability and cross-sectional validity are calculated for these 8 measures using this normative database.  The second part of the study draws on longitudinal data from the Seattle Social Development Project to create the same 8 measures of general and drug-specific environmental influence in adolescence, and then tests their capacity to predict prospectively adult substance use disorder. 

Results.  Reliabilities of the 8 general and drug-specific environmental domain scales tested in the CTC normative database ranged from .79 to .92. Furthermore, these 8 factors were strongly associated with adolescent alcohol, tobacco and marijuana use cross-sectionally. When created in the SSDP longitudinal sample, again these 8 general and drug-specific environmental domains scales were reliable (alpha from .70 to .85), and were prospectively strongly predictive of adult alcohol use disorder, daily smoking and tobacco dependence, marijuana abuse and dependence, and related outcomes.

Conclusions. Results suggest that conceptualizing the environment in terms of general functioning and risk behavior-specific components would provide an informative approach to prevention planning. For example, smoking prevention programs may consider including both components that improve general family functioning and components that address family smoking environment specifically.