Moderation of Genetic Influences on Alcohol Involvement by Rural Residency among Adolescents: Results from the 1962 National Merit Twin Study

Abstract

Adolescents in rural and urban areas may experience different levels of environmental restrictions on alcohol use, with those in rural areas experiencing greater monitoring and less access to alcohol. Such restrictions may limit expression of genetic vulnerability for alcohol use, resulting in a gene–environment interaction (G × E). This phenomenon has previously been reported in Finnish and Minnesota adolescents. The current study used data from 839 same-sex twin pairs from the 1962 National Merit Scholarship Qualifying Test to determine whether the G × E interaction would be evident in this earlier time period. We also assessed whether the G × E interaction would be moderated by sex, and whether family socioeconomic status (SES; income and parental education) may mediate the G × E interaction. Findings showed the expected interaction among females, with a weaker contribution of genes (2 vs. 44%) and greater contribution of shared environment (62 vs. 29%) to variation in alcohol involvement among rural as compared to urban residents. The G × E interaction was not observed among males, and operated independently from differences in family SES among rural and urban adolescents. This study represents a partial replication in a novel setting of the moderation of the genetic contribution to alcohol use by rural/urban residency, and suggests that SES differences may not explain this effect.

Socioeconomic Status and Adolescent Alcohol Involvement: Evidence for a Gene–Environment Interaction

“…In prior research using the current sample, differences in family SES did not explain rural moderation of genetic influences on alcohol use among adolescent females (Davis et al, 2017). Genetic influences on alcohol involvement were lower for females in rural areas compared with females living in urban areas.…”

Neighborhood alcohol outlet density and genetic influences on alcohol use: evidence for gene–environment interaction

“…The modest sample size also made it necessary to combine the data from men and women in the analyses. Although the bulk of the evidence suggests that the contribution of genetic and environmental factors to alcohol use and disorder among men and women is similar (Salvatore et al ., 2017), there may be important differences in how they are moderated by neighborhood environmental characteristics (Dick et al , 2001; Davis et al , 2017). Similarly, although our sample was racially diverse, it was necessary to combine the data from individuals from different racial/ethnic groups in the analyses.…”

The Pennsylvania Longitudinal Study of Parents and Children (PALSPAC) Twin Registry

“…Thus, a PA-based twin registry will have substantial numbers of urban and rural twin-pairsfacilitating examination of life influences on developmental processes across these critically different environments. This is especially important as there has been very little genetically informed research on rural populations to date (e.g., Connolly et al, 2017;Davis et al, 2017;Dick et al, 2009;Legrand et al, 2008). Second, PA's level of out-migration is among the lowest in the USA, with approximately 72% of the residents being born in PA (U.S. Census Bureau, 2010Bureau, , 2017.…”