Shared genetic contributions to early-onset drinking and drinking to cope motives

Introduction: Recent evidence from empirical studies indicates that individuals who begin drinking at an early age may be more likely to use alcohol to cope with negative mood states and stress; however, the mechanisms underlying this association are unclear. One possibility is that early drinking directly increases risk for drinking to cope (DTC). Alternatively, the association between early drinking and DTC may be indirect, attributable to overlapping genetic or environmental factors. No prior genetically informative study has investigated the sources of covariation underlying the early-onset drinking-DTC association. Method: Early-onset drinking (before age 15) was assessed using structured clinical interviews in a sample of 7130 male and female participants aged 19-56 years from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders (VATSPSUD, Kendler & Prescott, 2006). DTC was assessed using the mood management scale of the alcohol use inventory (Horn & Wanberg, 1983). The sources of the covariation between early first drink and DTC were estimated using bivariate twin modeling. Results: Early drinking onset was reported by 28% of males and 16% of females and was associated with significantly higher DTC scores (phenotypic correlation: males = .19, females = .22). Results from bivariate twin models indicated that the association between early-onset drinking and DTC was completely attributable to shared genetic factors that contribute to both behaviors. Conclusions: Greater DTC among early-onset drinkers may not reflect a direct causal process, as shared biological pathways may explain vulnerability to stress-related drinking seen among early-onset drinkers. (C) 2012 Elsevier Ltd. All rights reserved.