Relative Addictiveness of Drugs
By Philip J. Hilts, New York Times, Aug. 2, 1994 Is Nicotine Addictive? It Depends on Whose Criteria You Use. Experts say the definition of addiction is evolving.
WASHINGTON - When heavily dependent users of cocaine are asked to compare the urge to take cocaine with the urge to smoke cigarettes, about 45 percent say the urge to smoke is as strong or stronger than that for cocaine.
Among heroin' addicts, about 3 percent rank the urge to smoke as equal to or stronger than the urge to take heroin. Among those addicted to alcohol, about 50 percent say the urge to smoke is at least as strong as the urge to drink.
Yet seven chief executives of tobacco companies testified under oath before a Congressional subcommittee in April that nicotine was not addictive. Experts in addiction disagree with that assessment, hut they say that the definition of addiction is evolving, and that they can see how such a statement might be made. <3>Hearings on Smoking This week, the Food and Drug Administration is holding hearings to consider whether cigarettes fit in the array of addictive drugs and whether the Government should regulate them.
The standard definition of addiction comes from the American Psychiatric Association and the World Health Organization, which list nine criteria for determining addiction. The two groups, which prefer the term drug dependence, base their definition on research done since the 1960's, which has determined that multiple traits must be considered in determining whether a substance is addictive. Thus although cigarettes do not offer as intense an effect as drugs like heroin and cocaine, they rank higher in a number of other factors. They not only create dependence among users but also elicit a high degree of tolerance, the need for more and more of drug to satisfy a craving. When all the factors are added up, the consensus among scientists is that nicotine is strongly addictive.
In smoking, it is not the nicotine addiction that is most harmful, but other toxic chemicals produced by burning tobacco, which cause most of the 400,000 deaths each year that are attributed to smoking.
Dr. Lynn T. Koslowski, an addiction expert at Pennsylvania State University, said addiction could generally be defined as "the repeated use of a psychoactive drug which is difficult to stop." He added that there might be many explanations for why it was hard to stop, including withdrawal that was too disturbing, or a high that was too enticing.
A diagnosis of mild dependence on a psychoactive drug is determined by meeting three of the nine criteria. Five items show moderate dependence and seven items indicate a strong dependence. (Not all nine items apply to each drug. For example, time and effort spent acquiring a drug are a significant feature of heroin addiction, but have no meaning in nicotine addiction.) <3>Criteria of Addiction
- Taking the drug more often or in larger amounts than intended.
- Unsuccessful attempts to quit; persistent desire, craving.
- Excessive time spent in drug seeking.
- Feeling intoxicated at inappropriate times, or feeling withdrawal symptoms from a drug at such times.
- Giving up other things for it.
- Continued use, despite knowledge of harm to oneself and others.
- Marked tolerance in which the amount needed to satisfy increases at first before leveling off.
- Characteristic withdrawal symptoms for particular drugs.
- Taking the drug to relieve or avoid withdrawal.
Before applying a test of the nine criteria, the expert first determines if the symptoms have persisted for at least a month or have occurred repeatedly over a longer period of time.
Asked about the tobacco executives' testimony on addiction, Dr. Kozlowski said, "In a way, I can see how they could say that. It has to do with a mistaken image of what addiction is, and I have many well-educated, intelligent people say something like that to me. People often think of a person taking one injection of heroin and becoming hopelessly addicted for the rest of their lives. That is wrong."
In addition, he said, when people tend to think of the high that heroin produces, one that is about as intense as cocaine and alcohol, they cannot believe cigarettes are in the same category. And they are not. Even though in large doses nicotine can cause a strong high and hallucinations, the doses used in cigarettes produce only a very mild high.
But researchers now know, says Dr. Jack Henningfield, chief of clinical pharmacology at the Addiction Research Center of the Government's National Institute on Drug Abuse, that many qualities are related to a drug's addictiveness, and the level of intoxication it produces may be one of the least important.
If one merely asks how much pleasure the drugs produce, as researchers used to do and tobacco companies still do, then heroin or cocaine and nicotine do not seem to be in the same category. Dr. Kozlowki said, "It's not that cigarettes are without pleasure, but the pleasure is not in the same ball park with heroin."
But now, he said, there are more questions to ask. "If the question is How hard is it to stop? then nicotine a very impressive drug," he said. "Its urges are very similar to heroin."
Among the properties of a psychoactive drug - how much craving it can cause, how severe is the withdrawal, how intense a high it brings - each addicting drug has its own profile.
Heroin has a painful. powerful withdrawal, as does alcohol. But cocaine has little or no withdrawal. On the other hand, cocaine is more habit-forming in some respects, it is more reinforcing in the scientific terminology, meaning that animals and humans will seek to use it frequently in short periods of time, even over food and water.
Drugs rank differently on the scale of how difficult they are to quit as well, with nicotine rated by most experts as the most difficult to quit.
Moreover, it is not merely the drug that determines addiction, says Dr. john R. Hughes, an addiction expert at the University of Vermont. It is also the person, and the circumstances in the person's life. A user may be able to resist dependence at one time and not at another.
A central property of addiction is the user's control over the substance. With all drugs. including heroin, many are occasional users. The addictive property of the substance can be measured by how many users maintain a casual habit and how many are persistent, regular users.
According to large Government surveys of alcohol users, only about 15 percent are regular. dependent drinkers. Among cocaine users, about 8 percent become dependent. For cigarettes, the percentage is reversed. About 90 percent of smokers are persistent daily users, and 55 percent become dependent by official American Psychiatric Association criteria, according to a study by Dr. Naomi Breslau of the Henry Ford Health Sciences Center in Detroit. Only 10 percent are occasional users.
Surveys also indicate that two-thirds to four-fifths of smokers want to quit but cannot, even after a number of attempts. Dr. John Robinson, a psychologist who works for the R. J. Reynolds Tobacco Company, contests the consensus view of nicotine as addictive. Using the current standard definition of addiction, he said at a recent meeting on nicotine addiction, he could not distinguish "crack smoking from coffee drinking, glue sniffing from jogging. heroin from carrots and cocaine from colas."
It is not that Dr. Robinson and other scientists supported by tobacco companies disagree with the main points made by mainstream scientists. but that they define addiction differently. Dr. Robinson says intoxication that is psychologically debilitating is the major defining trait of an addicting substance. It is a feature that was part of standard definitions of the 1950's, and is still linked to popular ideas about addiction, but which experts now say is too simplistic and has been left behind as scientific evidence accumulates.
Experts Rate Problem Substances
Dr. Jack E. Henningfield of the National Institute on Drug Abuse and Dr. Neal L. Benowitz of the University of California at San Francisco ranked six substances based on five problem areas. - Withdrawal: Presence and severity of characteristic withdrawal symptoms.
- Reinforcement: A measure of the substance's ability, in human and animal tests, to get users to take it again and again, and in preference to other substances.
- Tolerance: How much of the substance is needed to satisfy increasing cravings for it, and the level of stable need that is eventually reached.
- Dependence: How difficult it is for the user to quit, the relapse rate, the percentage of people who eventually become dependent, the rating users give their own need for the substance and the degree to which the substance will be used in the face of evidence that it causes harm.
- Intoxication: Though not usually counted as a measure of addiction in itself, the level of intoxication is associated with addiction and increases the personal and socIal damage a substance may do.
1 = Most serious 6 = Least serious HENNINGFIELD RATINGS Substance Withdrawal Reinforcemt Tolerance Dependnce Intoxictn ----------- ---------- ----------- --------- --------- --------- Nicotine 3 4 2 1 5 Heroin 2 2 1 2 2 Cocaine 4 1 4 3 3 Alcohol 1 3 3 4 1 Caffeine 5 6 5 5 6 Marijuana 6 5 6 6 4 BENOWITZ RATINGS Substance Withdrawal Reinforcemt Tolerance Dependnce Intoxictn ----------- ---------- ----------- --------- --------- --------- Nicotine 3* 4 4 1 6 Heroin 2 2 2 2 2 Cocaine 3* 1 1 3 3 Alcohol 1 3 4 4 1 Caffeine 4 5 3 5 5 Marijuana 5 6 5 6 4 *equal ratings
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