Genes May Influence Quitting Success
The authors say their findings support the idea there should be more individualized treatments to help people quit smoking. The study also suggests there may be a need to use genetic screening to identify those whose genes may make them more susceptible to nicotine addiction.
For their study the researchers investigated the CHRNA5-CHRNA3-CHRNB4 cluster of nicotine receptor genes that are already known to play an important role in nicotine dependence and heavy smoking.
They used data from two studies that had investigated these genes: one was a a community-based, cross-sectional study involving over 5,000 participants, and the other was a randomized comparative effectiveness smoking cessation trial involving over 1,000 people.
Using statistical tools they tested the relationship between measures of smoking cessation (focusing on age at cessation and relapse) and the presence of the high risk form of the gene cluster.
They found that individuals carrying the high-risk form of the gene cluster were more likely to quit when they were older: they reported a 2-year median delay in quit age compared to participants who had the low-risk form of the genes.
There was also a pattern of heavier smoking among the high-risk gene carriers.
The clinical trial data showed that participants with the high-risk versions of the genes who were taking placebo versions of quitting drugs, were more likely to fail attempts to quit compared to low-risk gene carriers.
But, those in the high risk gene group who took medications approved for nicotine cessation, such as bupropion and nicotine replacement therapies, had a higher chance of staying off tobacco than their high risk counterparts who took placebo.
First author Li-Shiun Chen, of the Washington University School of Medicine, St. Louis, told the press:
"We found that the effects of smoking cessation medications depend on a person's genes."
The participants with the highest risk showed a three-fold increase in their chance of staying off tobacco to the end of active treatment compared to those on placebo, suggesting this was the group that most benefited from these smoking cessation medications.
"If smokers have the risk genes, they don't quit easily on their own and will benefit greatly from the medications. If smokers don't have the risk genes, they are likely to quit successfully without the help of medications such as nicotine replacement or bupropion," explained Chen.
Figures from the US Centers for Disease Control and Prevention (CDC) show that smoking or exposure to secondhand smoke is responsible for 1 in 5 deaths in the US every year (amounting to 440,000 preventable deaths) and 8.6 million people live with a serious illness caused by smoking.
In spite these well-reported figures, over 46 million adult Americans continue to smoke.
Thursday is World No Tobacco Day. Observed around the world every year on 31 May, the date is intended to encourage a 24-hour period of abstinence from all forms of tobacco consumption.
This year, the World Health Organization (WHO) has chosen to focus on on the need to expose the tobacco industry's "attempts to undermine global tobacco control efforts".
Others have chosen to mark the occasion differently: for instance, the Dubai authorities have banned the sale of tobacco products for 24 hours, according to a report in The Times of India.
Written by Catharine Paddock PhD