Quit Smoking - Research Annual Report 2005

Rachel Tyndale: A new approach to help people quit smoking

Although we all know the dangers of tobacco smoking, our efforts to help people quit have been only partly successful.

Dr. Rachel Tyndale, Head of the Pharmacogenetics Research Section at CAMH, is tackling the serious public health issue of smoking by trying to better understand why some people smoke more than  others, and why some find it easier to quit.

One answer may lie in our genes. We know that variations in genes can account for why some people respond to drugs differently than others. Understanding the role such  variations play in why and how we become addicted to smoking can give us a new approach to individualized medicine. Dr. Tyndale's  goal is to use genetic information to personalize treatment for people who want to quit smoking.
At CAMH, her work has already evolved from very basic studies in the test tube to  clinical drug trials, based on her scientific findings, in people who are dependent on nicotine (the substance in tobacco responsible for dependence).

Dr. Tyndale's laboratory investigations initially focused on the genetic differences among people who smoke, in the enzyme that breaks down nicotine.

She discovered that some people have  a genetic variation in this enzyme that causes them to break down, or metabolize, nicotine slowly. These people are less likely to smoke, smoke less each day if they do smoke and have greater success in quitting smoking.  A different variant of the same gene has the opposite effect in other people: their bodies break down nicotine faster. These people are more likely to smoke heavily, have greater problems quitting and have more smoking-related health problems, such as lung cancer.

Dr. Tyndale's hope is that, in future, when people seek help for nicotine dependence, clinicians will be able to look first at the person's genetic makeup to see whether that person will metabolize nicotine quickly or slowly and then tailor treatment accordingly.

In clinical trials, Dr. Tyndale found  that people who metabolize nicotine slowly are able to quit smoking more efficiently,  and that their efforts to quit are enhanced  by smoking cessation drugs.

Preliminary data from other clinical  studies suggest that drugs that can block  the metabolism of nicotine can reduce daily smoking. These studies show great promise, and her group is preparing for larger-scale clinical trials.

"The really exciting part of my research is the possibility of using genetic information, for the first time, to individualize treatment to help smokers quit this highly addictive drug."- Dr. Rachel Tyndale.

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