| Summary: | The aim of this doctoral thesis is to provide a better understanding of the effects of prenatal cigarette smoke exposure (PCSE) and of the combined effects between PCSE and catecholaminergic, serotonergic and metabolic genes on externalizing behaviours at school age in a sample of Inuit children from Nunavik. The association between PCSE and externalizing behaviours is first explored in a sample of children (N = 271) at 11 years of age who took part in a prospective study. Interactions between PCSE, lead (Pb) and mercury (Hg), two contaminants associated with behavioral problems, were also explored. Analysis of PCSE effects (Article 1) suggests that PCSE is associated with externalizing behaviours and with attention problems on the Teacher Report Form (TRF), and PCSE is also associated with a higher prevalence of attention deficit hyperactivity disorder (ADHD) assessed on the Disruptive Behavior Disorders (DBD). No interactions were found with contaminants. Then, the analysis of the combined effects between PCSE and catecholaminergic, serotonergic, and metabolic genetic polymorphisms (Article 2) suggests an interaction between PCSE and genotypes CC/TC of the cytochrome P-450 1A1 (CYP1A1) gene. Unexposed children with genotypes CC or TC have significantly lower scores for externalizing behaviours. Combination of an environment without PCSE and with genotypes CC/TC seems to offer protection regarding the development of externalizing problems. These results partly support the differential susceptibility model and reject the diathese stress model. This thesis suggests that PCSE is a risk factor in the development of externalizing problems and those genetic variations can modify this relation. Results indicate the importance of including different theoretical frameworks in the investigation of gene-environment interactions. L’objectif de cette thèse doctorale est de contribuer à une meilleure compréhension des effets de l’exposition prénatale au tabac (EPT) et des effets de l’interaction GxE entre l’EPT et des ...
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