Results : We confirmed the importance of the 4 main factors influencing SC : ( 1 ) environmental factors , ( 2 ) genomic factors , ( 3 ) gene-environment interactions , and ( 4 ) evidence -based interventions .
The model demonstrates the complex network of factors influencing SC .
Background : Smoking behaviour is a major public health problem worldwide .
Several sources have confirmed the implication of genomic factors in smoking behaviour .
These factors interact both with environmental factors and interventions to develop a certain behaviour .
Objectives : Describing the environmental and genomic factors as well as the interventions influencing smoking cessation  ( SC ) and developing a working model incorporating the different factors influencing SC were our main objectives .
Pharmacogenetic clinical trial of sustained-release bupropion for smoking cessation.
This r and omized , double-blinded , placebo-controlled trial examined genetic influences on treatment response to sustained-release bupropion for smoking cessation . Smokers of European ancestry ( N = 291 ) , who were r and omized to receive bupropion or placebo ( 12 weeks ) plus counseling , were genotyped for the dopamine D2 receptor ( DRD2-Taq1A ) , dopamine transporter ( SLC6A3 3 ' VNTR ) , and cytochrome P450 2B6 ( CYP2B6 1459 CT ) polymorphisms . Main outcome measures were cotinine-verified point prevalence of abstinence at end of treatment and at 2- , 6- , and 12-month follow-ups post quit date . Using generalized estimating equations , we found that bupropion , compared with placebo , was associated with significantly greater odds of abstinence at all time points ( all p values<.01 ) . We found a significant DRD2 x bupropion interaction ( B = 1.49 , SE = 0.59 , p = .012 ) [ corrected ] and a three-way DRD2 x bupropion x craving interaction on 6-month smoking cessation outcomes ( B = -0.45 , SE = 0.22 , p = .038 ) , such that smokers with the A2/A2 genotype demonstrated the greatest craving reduction and the highest abstinence rates with bupropion . Furthermore , there was a significant DRD2 x CYP2B6 interaction ( B = 1.43 , SE = 0.56 , p = .01 ) , such that individuals with the DRD2-Taq1 A2/A2 genotype demonstrated a higher odds of abstinence only if they possessed the CYP2B6 1459 T/T or C/T genotype . Because the sample size of this study was modest for pharmacogenetic investigations , the results should be interpreted with caution . Although these results require replication , the data suggest preliminarily that the DRD2-Taq1A polymorphism may influence treatment response to bupropion for smoking cessation and , further , that exploration of gene x gene and gene x craving interactions in future , larger studies may provide mechanistic insights into the complex pharmacodynamics of bupropion
Results : We confirmed the importance of the 4 main factors influencing SC : ( 1 ) environmental factors , ( 2 ) genomic factors , ( 3 ) gene-environment interactions , and ( 4 ) evidence -based interventions .
The model demonstrates the complex network of factors influencing SC .
Background : Smoking behaviour is a major public health problem worldwide .
Several sources have confirmed the implication of genomic factors in smoking behaviour .
These factors interact both with environmental factors and interventions to develop a certain behaviour .
Objectives : Describing the environmental and genomic factors as well as the interventions influencing smoking cessation  ( SC ) and developing a working model incorporating the different factors influencing SC were our main objectives .