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 .
Genetic variation in the dopamine D4 receptor (DRD4) gene and smoking cessation: follow-up of a randomised clinical trial of transdermal nicotine patch
Smokers of European ancestry ( n=720 ) who participated in a double-blind , r and omised , placebo-controlled trial of transdermal nicotine replacement therapy  , were genotyped for two functional polymorphisms ( variable number of t and em repeats ( VNTR ) and a C to T transition at position –521 ( C-521 T ) ) in the dopamine D4 receptor gene ( DRD4 ) gene . Logistic regression models of abstinence at 12- and 26-week follow-ups were carried out separately for each polymorphism . For the DRD4 VNTR models , the main effect of treatment was significant at both 12-week ( P=0.001 ) and 26-week ( P=0.006 ) follow-ups , indicating an increased likelihood of successful cessation on active nicotine replacement therapy transdermal patch relative to placebo . The main effect of DRD4 VNTR genotype was associated with abstinence at 12-week follow-up ( P=0.034 ) , with possession of one or more copies of the long allele associated with reduced likelihood of cessation ( 17 vs 23 % ) , but this effect was not observed at 26-week follow-up . For the DRD4 C-521 T models , no main effect or interaction terms involving genotype were retained in the models at either 12- or 26-week follow-up . These data are consistent with observations from studies of the DRD2 gene that genetic variants related to relatively decreased dopaminergic tone in the mesocorticolimbic system are associated with increased risk for relapse to smoking following a cessation attempt
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 .