Twin studies suggest that propensity to smoke and ability to quit smoking are influenced by genetic factors. As a means of investigating the risk of smoking associated with genetic polymorphisms in the dopamine transporter (SLC6A3) and the D2 dopamine receptor (DRD2) genes, a case-control study of 289 smokers and 233 nonsmoking controls and a case series analysis of smokers were conducted. A significant effect for SLC6A3 and a significant gene-gene interaction were found in a logistic regression model, indicating that individuals with SLC6A3-9 genotypes were significantly less likely to be smokers, especially if they also had DRD2-A2 genotypes. Smokers with SLC6A3-9 genotypes were also significantly less likely to have started smoking before 16 years of age and had prior smoking histories indicating a longer period of prior smoking cessation. This study provides preliminary evidence that the SLC6A3 gene may influence smoking initiation and nicotine dependence.

OBJECTIVES. A randomized trial (the Birmingham Trial II) was conducted to evaluate the behavioral impact of health education methods among 814 female smokers at four public health maternity clinics. METHODS. Four hundred patients were randomly assigned to an Experimental (E) Group, and 414 were assigned to a Control (C) Group. Self-reports and saliva cotinine tests confirmed smoking status at the first visit, at midpregnancy, and at end of pregnancy. RESULTS. The E Group exhibited a 14.3% quit rate and the C Group an 8.5% quit rate. A Historical Comparison (C) Group exhibited a 3.0% quit rate. Black E and C Group patients had higher quit rates than White E and C Group patients. A cost-benefit analysis found cost-to-benefit ratios of $1:$6.72 (low estimate) and $1:$17.18 (high estimate) and an estimated savings of $247,296 (low estimate) and $699,240 (high estimate). CONCLUSION. Health education methods are efficacious and cost beneficial for pregnant smokers in public health maternity clinics.

In this article the authors report on the short-term impact of incorporating biomarker feedback about exposure and genetic susceptibility into minimal-contact quit-smoking counseling (QSC). Four hundred and twenty-seven smokers were randomized to 1 of 3 treatments: (a) QSC, (b) QSC + exposure biomarker feedback (EBF) about carbon monoxide in exhaled breath, or (b) QSC + EBF + biomarker feedback about genetic susceptibility to lung cancer (SBF). We observed significant immediate positive effects of SBF, compared with EBF and QSC on perceived risk, perceived quitting benefits, and fear arousal. However, at the 2-month follow-up, there were no group differences in quit rates. SBF did lead to significant reductions in the number of cigarettes smoked for smokers who were in the preparation stage. Smokers in the EBF and QSC conditions showed reductions in depressive symptoms by 2 months, but smokers in the SBF condition did not. In the context of QSC, genetic feedback may heighten vulnerability and possibly promote distress, but may not immediately enhance quitting in most smokers.

This study evaluated whether there are genetic subgroups of depressed individuals who are more or less predisposed to engage in self-medication smoking practices. Smokers (N = 231) completed self-report questionnaires of depression and smoking practices and were genotyped for the dopamine D4 receptor (DRD4) gene. A significant interaction (DRD4 Genotype x Depression) was found for stimulation smoking and negative-affect reduction smoking. Specifically, these smoking practices were significantly heightened in depressed smokers homozygous for the short alleles of DRD4 but not in those heterozygous or homozygous for the long alleles of DRD4. These preliminary results suggest that the rewarding effects of smoking and the beneficial effects of nicotine replacement therapy for depressed smokers may depend, in part, on genetic factors involved in dopamine transmission.

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