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Statement on Nicotine before the Committee on Labor and Human Resources, U.S. Senate

Alan I. Leshner, Ph.D.
Director
National Institute on Drug Abuse
National Institutes of Health
Department of Health and Human Services

February 10, 1998

 

Statement of the Director

Mr. Chairman and Members of the Committee, I am pleased to be here with my distinguished colleagues to discuss current research findings and future research directions on one of the Nation's deadliest and most costly health problems--use of tobacco products. It is addiction to nicotine that is at the root of this enormous burden.

Scientific research has determined that nicotine is in fact a highly addictive drug. Nicotine addiction, like other drug addictions, is characterized by compulsive drug seeking and use, even in the face of negative health consequences. A testimony to this fact is that most smokers identify smoking as harmful and nearly 35 million of them attempt to quit each year. Yet only a very small fraction of them actually succeed.

Emerging basic research is reinforcing what earlier studies have indicated about the highly addictive nature of nicotine. Let me share with you a sampling of some of our most recent and interesting research findings.

Recently we have been able to prove what has been only inferred from earlier research, that some of nicotine's most important effects are exerted through the very same brain circuits as those of other drugs of abuse. Researchers found nicotine, just like cocaine, heroin and marijuana, activates dopamine containing neurons in the critical brain pathways that control reward and pleasure. This finding supports a convergence of data pointing toward at least one major commonality among all drugs of abuse: they all elevate levels of the neurotransmitter dopamine. It is this change in dopamine that is believed to be a fundamental root of all addictions.

Another new and exciting finding published just last month, scientists pinpointed a particular protein, the beta 2 subunit of the nicotinic cholinergic receptor as being essential to the process of nicotine addiction. Using sophisticated bioengineering tools, these researchers produced a new strain of knockout mice which lack this important protein. Mice without this receptor would not self administer nicotine, whereas those who had the receptor readily sought to give themselves nicotine infusions. This clearly demonstrates that this beta 2 subunit is an important mediator of nicotine's addictive properties.

Nicotine may not be the only psychoactive ingredient in tobacco, however. Using advanced neuroimaging (PET) technology we are now actually able to see what tobacco smoking is doing to the brain of an awake and behaving human being. This poster shows one dramatic effect that cigarette smoking has on the brain. Here you can see a tremendous decrease in the levels of an important enzyme known to be responsible for breaking down dopamine, called monoamine oxidase- B (MAO-B). The net effect of this reduction in MAO-B is an increase in dopamine levels. Importantly, this particular effect is not caused by nicotine but by some additional, unknown compound in cigarette smoke. Nicotine itself does not alter MAO-B levels; it affects dopamine through other mechanisms. Thus there may be multiple routes by which smoking alters the neurotransmitter dopamine, and, again, this neurochemical is centrally implicated in the effects of all addictive substances.

Through studies like this we are unraveling the mysteries of not only smoking as an addiction, but these findings are giving us new information that may be relevant to other addictions as well.

Through NIDA's leadership, the world now has a variety of effective pharmacological and behavioral treatments to select from to help people conquer their smoking addiction, but we need more. Addiction researchers have developed a number of new pharmacological weapons to combat nicotine addiction. For example, several nicotine-replacement therapies, including the patch and gum are now readily available in local drug stores and supermarkets. In addition our scientists are working on a number of non-nicotine replacement therapies as well. The preeminent compound in this line is Buproprion, which you may know as Zyban®. Originally marketed as Welbutrin®, an anti-depressant, this compound is showing promising results in treating nicotine addiction as well.

While we have a number of treatments that have proven to be effective for many people, we still do not have enough in our clinical toolbox. NIDA will continue to build upon its basic addiction research portfolio to identify and develop innovative approaches to treat nicotine addiction.

Of course, recognizing that smoking is a complex behavioral as well as a pharmacological problem, it needs to be approached as such. Thus behavioral interventions play an integral role in nicotine addiction treatment. To further improve the efficacy of these combined approaches, we must better understand the antecedents of tobacco use, and learn how to change behavior patterns. Both research and extensive clinical experiences have taught us that treating the addiction with just medications is not nearly as effective as when we couple the medication with a behavioral approach.

We know that more than 90 percent of the people who try to quit smoking, relapse or return to smoking within one year. The majority of them relapse within a week. There are however, two and-a-half to five percent, who do in fact succeed on their own. It has been shown that pharmacological treatments can double the odds of their success. However, a combination of pharmacological and behavioral treatments can even further improve their odds. For example when use of the nicotine patch is combined with a behavioral approach, such as group therapy or social support networks, the efficacy of treatment is enhanced.

Just as with other drugs, ultimately our best treatment is prevention. Twenty years of prevention research has given us the tools that we need to develop effective programs to prevent people from beginning to smoke, even young people.

This holds for other drugs of abuse as well. The time of common sense approaches and intuition in preventing drug use is over. We have a science base for prevention and we need to use it. Toward this end, NIDA has produced the first ever research-based guide for preventing drug use. The very same principles espoused in this red book, "Preventing Drug Use Among Children and Adolescents, " hold for all drugs of abuse, including nicotine. These principles can be applied by families, schools and communities to ensure the health and well being of future generations.

We are not stopping here however. We are forging ahead to identify risk factors that may make an individual more vulnerable to addiction. Understanding what makes a person vulnerable, and how they progress from their first drug exposure to abusing drugs to addiction will enable us to effectively target our prevention efforts to those who are most at risk. Just as important, however, is the identification of protective factors, those behaviors, environments, activities, etc. that seem to enable a person to avoid drug use altogether. Both risk and protective factors may be genetic, biological, environmental, social or cultural in nature, for nicotine, as well as for all other addictive drugs.

It is only through the recognition of tobacco use as an addiction that we will be able to eliminate many of its detrimental health effects. As with all other disorders, it is research on addiction that provides hope for even more effective prevention and treatment approaches.

The President stressed that the following five key elements must be at the heart of any national tobacco legislation:

  1. A comprehensive plan to reduce teen smoking, including a combination of penalties and price increases that raise cigarette prices up to $1.50 per pack over the next 10 years as necessary to meet youth smoking targets;
  2. Express reaffirmation that the FDA has full authority to regulate tobacco products;
  3. Changes in the way the tobacco industry does business;
  4. Progress toward other critical public health goals, such as the expansion of smoking cessation and prevention programs and the reduction of secondhand smoke; and
  5. Protection for tobacco farmers and their communities.

Never before has the momentum for addressing this public health crisis been greater. There are tremendous scientific opportunities, based on at least two decades of scientific accomplishments. We must seize the scientific opportunities that now present themselves to ensure that no more lives are lost to what is ultimately both a preventable and, if not prevented, a treatable disease.

Mr. Chairman, I would be pleased to answer any questions you may have. Thank you.

[Testimony Index]



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