Exploring the relationship between genetic and environmental influences on initiation and progression of substance use

Abstract

Aims To examine the genetic and environmental contributions to the initiation of use and progression to more serious use of alcohol, cigarettes and marijuana during adolescence, and to examine the relationship between initiation and progression of substance use. Design The study used a twin-based design and a new theoretical model, the causal-common-contingent (CCC) model. This allows modelling of the relationship between initiation of use and progression to heavier use as a two-stage model and the examination of genetic and environmental influences on both stages, while taking into account their relationship. Participants The participants consisted of 1214 twin pairs (69% response rate) aged 11-19 years sampled from the UK population-based Cardiff Study of All Wales and North-west of England Twins (CaStANET). Measurements Data on adolescent initiation and progression to more serious use of alcohol, cigarettes and marijuana were obtained using self-report questionnaires. Findings Initiation of alcohol and progression to heavier alcohol use had separate but related underlying aetiologies. For cigarette and marijuana use the relation between initiation and progression to heavier use was stronger, suggesting greater overlap in aetiologies. For all three substances, environmental influences that make twins more similar (common environment) tended to be greater for initiation, while genetic influences were stronger for heavier use. Conclusions These findings have implications for policy decisions aimed at an adolescent and early adult age group. Specifically, these findings suggest that it may be more efficacious to focus alcohol interventions on risk factors for the development of heavier use rather than initiation of use. In contrast, interventions aimed at reducing the initiation of cigarettes and marijuana use may be more appropriate.

Gene-Environment Correlation and Interaction in Peer Effects on Adolescent Alcohol and Tobacco Use

“…Previous research, however, has suggested that there may be qualitatively different risk factors for initiation versus progression of substance use, particularly for alcohol (Fowler et al 2007a;Heath et al 1991). Therefore, our results do not characterize etiological processes that are specific to initiation alone.…”

Psychiatric and familial predictors of transition times between smoking stages: Results from an offspring-of-twins study

“…An increase from early to later stage transitions in the overlap of variance in genetic risk for ND and AD with variance in alcohol and cannabis use would also explain this finding. Evidence for changes in the source of genetic contributions to smoking outcomes across stages (i.e., heritability of smoking initiation is not perfectly correlated with heritability for progression to heavier use [Fowler et al, 2006] or ND [Kendler et al, 1999;Maes et al, 2004]) lends support to this interpretation of the results.…”

Interaction between dopamine D2 receptor genotype and parental rule-setting in adolescent alcohol use: evidence for a gene-parenting interaction

“…3 Behavioral genetic studies with twin designs have shown a significant genetic component not only in alcohol dependence (explained variance 58% 4 ), but also in regular alcohol use (43% 5 ) and alcohol-related problems (38.5% 6 ). In addition, a genetic component of approximately 30% has also been identified for initiation of drinking 7,8 (see for an overview Poelen et al ).…”

“…Adolescence is a developmental period in which complex environmental influences within and outside the family codetermine the initiation and use of alcohol. 7,8 In other words, certain genetic polymorphisms may increase the likelihood that a person will develop alcohol dependence or will start using alcohol very early, but the actual manifestation of the disorder or habit might depend on environmental factors, 24,25 a so-called gene-environment (G Â E) interaction.…”