Why smoking's a drag
Suba, a trendy Latin restaurant on the lower East Side, serves a mean Nicotini, a nicotine-infused concoction of Kahlua and Stoli. Suba's owner, Yann De Rochefort, describes the drink as strong and spicy and says the restaurant introduced it last summer,
The citywide smoking ban has resulted in a spate of creative menu items and prevented people from lighting up in public spaces but it probably hasn't convinced many people to stop smoking. Despite legal, social and medical pressure, fewer than 25% of smokers succeed in quitting permanently.
Now a study has found that kicking the habit may be more than simply a matter of mind over Marlboro. It could be that genes are responsible for keeping some people addicted to cigarettes.
Researchers from the University of Pennsylvania's Transdisciplinary Tobacco Use Research Center examined 418 smokers enrolled in a clinical trial using the antidepressant bupropion (also marketed under the names Zyban and Wellbutrin) plus psychological counseling as an aid to ceasing smoking. At the end of six months, the researchers found that participants with variants of two genes, a dopamine transporter gene known as SLC6A3 and a dopamine receptor gene known as DRD2, had higher abstinence rates and were able to hold off from lighting up longer than smokers carrying Âother gene variants. According to Caryn Lerman, Ph.D., the study's lead author, this provides the first evidence that genes may influence a person's ability to quit.
"Some smokers may have an easier time quitting than others and this may be due in part to inherited predispositions to nicotine dependence," Lerman theorizes.
DNA from blood samples was taken at the beginning of the trial to determine which variants of the two genes the smokers had. Each smoker's smoking status, withdrawal symptoms and side effects were monitored every week during the ten weeks they received treatment and for six months thereafter.
More than half 53% of smokers with a specific combination of the two genes, had managed to abstain from smoking by the end of the treatment phase of the study, compared with only 39% of the others. They also lasted longer before ultimately giving into nicotine cravings. However, at the six-month follow up, the majority of the subjects, regardless of which gene variants they possessed, were unable to control their urges and were once again puffing away.
In the future, Lerman says, "it may be possible to select a particular treatment for a smoker based on his or her genetic background," Lerman says.
Dr. Marc K. Siegel, an internist at New York University Medical Center, isn't convinced that there is a "stop smoking gene" per se, or that the addictiveness of nicotine can be wholly explained away with genetics, but is intrigued by the possibiÂlity. "We advise our patients to try this or try that and it can be hit or miss," Siegel says. "Sincet about 70% of smokers make at least one quit attempt a year and that only 3-8% are successful, having a way to specifically target therapy to the individual would be extremely useful."
Other preliminary research supports the University of Pennsylvania's findings.
Similar genetic testing done at Oxford University in England allowed researchers to predict which subjects would respond well to a nicotine patch and which wouldn't.
Counseling helps in quitting
Nicotine, the active ingredient in tobacco, is highly addictive. There are numerous products and smoking cessation programs but currently the three most commonly prescribed anti-smoking aids are the nicotine patch, Zyban and hypnosis.
The patch, which is worn directly against the skin, delivers ever-diminishing doses of nicotine into the bloodstream in order to slowly wean the wearer from nicotine. Zyban, an antidepressant, helps by cutting back on cravings and easing withdrawal symptoms. It's not clearly understood why hypnosis works for some people though Siegel suspects it may help by allowing the individual to create a nonsmoker self-image.
You double your chances of quitting with any of these methods as opposed to going cold turkey, which has a less than 5% quit rate. Success of all cessation methods Âdoubles when combined with some type of psychological counseling.
Siegel says he's found that different people seem to respond to different therapies. "The patch seems to work best for people who are really nicotine addicted while people who need the smoking rituals, like tapping the pack on their wrist and lighting up a certain way, seem to do better with the pill," he says. "Hypnosis seems to be the most effective with Âintractable smokers."
In the past few years, medical experts have begun pairing two different cessation methods and this does seem to increase their effectiveness. A 1999 study published in the New England Journal of Medicine found that about 35% of people abstained from smoking for up to one year when they wore a nicotine patch in combination with taking Zyban.
An anti-nicotine vaccine is also in development. The vaccine, TA-NIC, is administered via intramuscular injection and acts by preventing nicotine from crossing the blood-brain barrier.
The immune system normally ignores small molecules like nicotine, so scientists have linked it to a larger molecule. Once the immune system makes antibodies to the combination, it will later recognize the naked drug, binding to it and keeping it from reaching the brain. Clinical trials began in Europe about two years ago and if all goes well, the vaccine will be on the market in about three years. Some scientists say that it may not only help people quit smoking but may also be used to prevent them from ever starting in the first place.
Cutting back doesn't cut risk
Those who aren't ready to give up cigarettes entirely often strive to cut back, a strategy Dorothy Hatsukami, Ph.D., a professor and researcher in department of psychiatry at the University of Minnesota, says may not be all that effective. "Damage from nicotine is only one of the negative effects from smoking," she explains. "There are dozens of other carcinogens in the smoke itself."
Hatsukami and her colleges have found that even when smokers reduce their cigarette intake by as much as 70% they only reduce the carcinogenic effects of smoking by about 30%.
"When smokers smoke fewer cigarettes they compensate by taking longer drags, more puffs, and by holding the smoke in their lungs longer," Hatsukami says.
Contrary to popular belief, "light" and "ultralights" are also no safer than conventional cigarettes. They contain the full dose of nicotine and though the filtered tips are supposed to dilute smoke byproducts with air, Hatsukami notes that, once again, most smokers compensate by covering the filter with their fingertips or lips, or by finding ways to maximize each puff.
New cigarettes, old dangers
While admitting that there is no such thing as a safe cigarette, tobacco companies are now seriously engaged in trying to design cigarettes that pose less of a health risk than the standard. Virginia-based Star Scientific markets Advance, which is made with a tobacco processing technology that prevents, or substantially reduces, the formation of tobacco specific nitrosamines (TSNAs). TSNAs are believed to be the most potent and abundant cancer-causing toxins in tobacco and tobacco smoke.
RJ Reynolds developed Eclipse, a smokeless brand in which the tobacco is superheated rather than burned. Among other things, the company claims this reduces secondhand smoke by up to 80%. And cigarette manufacturer Vector recently introduced reduced-nicotine and nicotine-free Quest cigarettes made from a genetically modified tobacco.
These products have received mixed reviews from the public health and medical communities. Many experts feel that they may prevent people from trying to quit and that, without eliminating the habit entirely, you can never reduce health risks to an acceptable level.
Others reject the products on more scientific grounds. For instance, Thomas Eisenberg, Ph.D., of the University of Virginia Commonwealth observes that the superheated tobacco approach taken by Eclipse releases a great deal of carbon monoxide into the air.
Independent studies have also found that Eclipse produced approximately equal or higher amounts of several potent carcinogenic chemicals as compared to "ultralight" brands.