Gene–environment interactions in addictive disorders: epidemiological and methodological aspects

The gene–environment interactions' approach could explain some epidemiological and clinical factors associated with addictive behaviours. Twin studies first help to disentangle the respective roles of environment and genetic effects, finding convincing evidence for common genetic vulnerability in several addictive behaviours, and helping to delimit what syndrome could belong to the addictive disorder spectrum. Assessing gene × environment interaction ( G × E ) needs specifically designed studies, using multiplicative or additive approaches. Focusing on this G × E interaction already showed its relevancy in many recent studies, using both epidemiological and molecular approaches. For example, in a non-human primate model of alcohol dependence assessing the respective role of genetic vulnerability (having the short allele located in the promoter region of the gene coding for the serotonin transporter) and severe fostering conditions (as locked up in a cage with other inmates for the first six months of life), the only group of monkeys that has a significant risk of using spontaneously alcohol is the one that gathers both risk factors, i.e. being peer-raised and having the short allele. Such approach could help to more accurately select specific candidate genes, to identify more homogenous subgroups of patients (as sharing the same genetic vulnerability), to understand how genetic factors mediate the risk of associated psychiatric disorders, and ultimately, may lead to more focused, i.e. more efficient, prevention strategies. To cite this article: P. Gorwood et al., C. R. Biologies 330 (2007). L'approche des interactions gène–environnement pourrait expliquer quelques-uns des facteurs épidémiques et cliniques associés aux comportements addictifs. Les études de jumeaux aident d'abord à déconvoluer les rôles respectifs de l'environnement et des effets génétiques, car elles aboutissent à une preuve convaincante d'une vulnérabilité génétique commune dans plusieurs addictions, et permettent de définir quel syndrome pourrait appartenir au spectre du désordre addictif. Mettre en évidence l'interaction gène × environnement ( G × E ) demande des études conçues spécifiquement, faisant appel à des approches multiplicatives ou additives. De nombreux travaux récents s'intéressant à cette interaction G × E , utilisant à la fois des approches épidémiologiques et moléculaires, ont déjà établi sa pertinence. Par exemple, dans un modèle de dépendance à l'alcool chez un primate