Social Work Today E-Zine

Common genetic variations affecting nicotine receptors in the nervous system can significantly increase the chance that European Americans who begin smoking by the age of 17 will struggle with lifelong nicotine addiction, according to a study published in a recent issue of PLoS Genetics. The study highlights the importance of public health efforts to reduce the number of youths who begin smoking.

The researchers studied 2,827 long-term European American smokers. They assessed the level of nicotine dependence for all smokers, and recorded the age they began daily smoking, the number of years they smoked, and the average number of cigarettes smoked per day. DNA samples were taken from all smokers, and the researchers recorded the occurrence of common gene variations, grouped into four haplotypes, which had been identified earlier in a subset of participants.

They found that people who began smoking before the age of 17 and possessed two copies of the high-risk haplotype had a 1.6-fold to almost 5-fold increase in risk of heavy smoking as an adult. For people who began smoking at the age of 17 or older, presence of the high-risk haplotype did not significantly influence their risk of later addiction. The high-risk haplotype is common in the three study populations, and European American populations in general, ranging in frequency from 38% to 41%.

Although the authors caution that different haplotype frequencies would likely be observed in different ethnic populations, Robert Weiss, PhD, professor of human genetics at the University of Utah and lead author of the study explains, “We know that people who begin smoking at a young age are more likely to face severe nicotine dependence later in life. This finding suggests that genetic influences expressed during adolescence contribute to the risk of lifetime addiction severity produced from the early onset of tobacco use.”

— Source: University of Utah Health Sciences