Association between dopamine beta hydroxylase rs5320 polymorphism and smoking behaviour in elderly Japanese

The dopaminergic brain pathway is involved in many addictive behaviours, hence represents a good candidate in the study of smoking behaviour and nicotine addiction. Dopamine beta hydroxylase (DBH) is an enzyme that catalyses the conversion of dopamine into noradrenaline. This study, the first of its kind, was done to investigate the role of DBH rs5320 polymorphism in smoking behaviour of elderly Japanese. This was done by collecting blood samples from 2521 subjects with various smoking habits to genotype the DBH rs5320 polymorphism. Participants also had to fill out a questionnaire containing questions regarding their lifestyles. Some of the questions were from the Fagerström Test for Nicotine Dependence (FTND) and the Tobacco Dependence Screener (TDS). It was found that male ever-smokers with AA genotype smoked less cigarettes per day than those with GG and AG genotypes. FTND scores were also lowest in male ever-smokers with AA genotype and in female ever-smokers with AG genotype. There was no correlation detected between the TDS scores and any of the genotypes. This study shows that DBH rs5320 polymorphism influences nicotine dependence.