Genetic variations 'affect nicotine addiction'
Friday, 11 Jul 2008 01:01
Genetic variations can affect nicotine addiction, study says
European Americans who begin smoking before the age of 17 may be more likely to become addicted to nicotine if they have a common genetic variation, a new study has found.
Researchers in the United States found that teenagers with the variation, which affects nicotine receptors in the nervous system, can significantly increase the chance they will struggle with life-long nicotine addiction.
They say their findings highlight the importance of preventing early exposure to tobacco through public health policies.
The team studied 2,827 long-term European American smokers, assessing the level of nicotine dependence for all smokers; recording the age they began smoking daily; 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 the genetic variation known as single nucleotide polymorphisms (SNPs) and haplotypes - a set of SNPs that are statistically linked.
They found that people who began smoking before the age of 17 and possessed two copies of the high-risk haplotype had from a 1.6-fold to almost five-fold increase in risk of heavy smoking as an adult.
For people who began smoking at age 17 or older, presence of the high-risk haplotype did not significantly influence their risk of later addiction.
Although the authors caution that different haplotype frequencies would likely be observed in different ethnic populations, lead author Dr Robert Weiss said: "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."
Commenting on the findings, National Institute on Drug Abuse (NIDA) director Dr Nora Volkow said: "This study adds to recent advances in understanding how genetic variation can affect susceptibility to nicotine addiction, success or failure of smoking cessation treatments, and the risk of disease associated with tobacco use.
"As we learn more about how both genes and environment play a role in smoking, we will be able to better tailor both prevention and cessation programmes to individuals."
The research is published in the journal PLoS Genetics.