Here's an excerpt about the term "addiction" from *Drugs, Society, and Human Behavior*, by Ray and Ksir: [excerpt begins] DRUG ADDICTION Problems of Definition ...There have been many definitions offered over the years for the term _drug addiction_, and this term has been so widely used and discussed that is has passed into that group of terms that elude precise definition... Discussions of addiction usually include some mixture of three more definable concepts: *tolerance*, *physical dependence*, and *psychological dependence*. Tolerance Tolerance refers to a phenomenon seen with most drugs in which repeated exposure to the same dose of the drug results in a diminishing effect. There are many ways in which this diminished effect can occur, and some examples will be given in Chapter 6. For now, it is enough for us to think of the body as developing ways to compensate for the unbalancing actions of these drugs. In many cases, as the individual experiences less and less of a desired effect, it is possible to increase the dose of the drug so as to counteract the tolerance. Since tolerance usually also develops to the dangerous effects of these drugs, some regular drug users may eventually build up to taking much more of the drug than it would take to kill a non-tolerant individual. Physical Dependence Suppose a person has begun to take a drug and a tolerance has developed. The person increases the amount of drug taken and continues to take these higher doses so regularly that his system is continuously exposed to the drug for days or weeks. With some drugs, if the person stops taking it abruptly, as the drug level in the system drops a set of symptoms begin to appear. For example, as the level of heroin drops in a heroin addict, his nose may run and he may begin to experience chills and fever, diarrhea, and so on. When we have a drug that produces a consistent set of these symptoms in different individuals, we refer to the collection of symptoms as a *withdrawal syndrome*. The withdrawal syndrome from all narcotics is similar to the heroin withdrawal syndrome, but different from the withdrawal syndrome produced by sedatives and sleeping pills. Our model for why these withdrawal symptoms appear is that the individual's nervous system has compensated for the presence of the drug and that some of these compensating mechanisms produce an imbalance when the drug is removed. An obvious example occurs among users of narcotic drugs, which tend to slow intestinal movement and produce constipation. After many days of constant narcotic use, other mechanisms in the body tend to counteract this effect and get the intestine moving again. If the narcotic is suddenly stopped, diarrhea is one of the most reliable and dramatic withdrawal symptoms. Because of the presumed involvement of these compensating mechanisms, the presence of a withdrawal syndrome is said to reflect physical dependence on the drug. In other words, the individual has come to depend on the presence of some amount of that drug to maintain a balance; removing the drug leads to an imbalance, which is slowly corrected over a period of a few days. Psychological Dependence *Psychological dependence* or sometimes "behavioral dependence" can also be defined or described in many ways. Some approaches to this have referred to the amount of effort an individual exerts in "drug-seeking" behavior, some to the frequency or regularity of drug taking, some to a stated craving for the drug. A major contribution of behavioral psychology has been to point out the scientific value of the concept of *reinforcement* in this context. It appears that some drugs have an ability to reinforce the behaviors that led up to the drug's presence in the system, in the same way that food pellets can reinforce lever-pressing behavior in hungry rats. Those drugs that have powerful reinforcing properties are the ones that we will consider to have a greater potential for producing psychological dependence. If a person takes a drug and the drug reinforces the drug-taking behavior, that means that if drug availability and the availability of other behaviors and other reinforcers remain relatively constant, the drug-taking behavior is likely to occur again. The Changing Views of Addiction Whether or not a drug is considered to be addicting may depend more on the definition of addiction than on the drug. Since the generally accepted view of addiction has shifted somewhat over the past 20 years, this has meant that some drugs once considered nonaddicting are now considered addicting. Although we don't want to imply that one view is now wrong and the other right or that everyone has changed his or her viewpoint in this time period, it is probably fair to distinguish an older and a more recent view of addiction.(9) When experts first began studying and defining addiction, the primary data with which they worked were the experiences of people addicted to heroin or other narcotic drugs. In fact, for many years concern about drug abuse was so focused on narcotics that all illegal drugs, including marijuana and cocaine, were referred to as narcotics in federal laws. Users of true narcotics sometimes show remarkable levels of tolerance and the withdrawal symptoms may be quite dramatic, and it was these on which the experts naturally focused in their definitions of addiction. Thus, addiction was usually defined largely in terms of physical dependence. It began to become a public issue in the 1960s that some drugs, particularly marijuana, were not really narcotics and did not produce the typical dramatic withdrawal syndromes. It became popular among the growing group of interested scientists to refer to drugs like marijuana, amphetamines, and cocaine as producing psychological dependence, whereas heroin produced a true addiction, including physical dependence. The idea seemed to be that psychological dependence was merely mental, whereas with physical dependence real bodily processes were involved, subject to physiological and biochemical analysis and possibly to improved medical treatments for addiction. Let us refer to this as the older view of addiction, the one held by most enlightened experts in the late 1960s. At about this time a remarkable series of experiments began to appear in the scientific literature; experiments in which laboratory monkeys and rates were given intravenous *catheters* connected to motorized syringes and controlling equipment in such a way that pressing a lever would produce a single brief injection of morphine, a heroinlike narcotic. As these scientists began to publish their results and as more experiments like this were done, they pointed out some interesting facts. First, it was not necessary to select monkeys with "addictive personalities" or rats born on the wrong side of the cage -- virtually every animal given the opportunity to press for morphine injections did so. Second was the degree to which results using morphine as a reinforcer could build on the vast literature of results using food or water reinforcers with animals: by requiring first 2 presses, then 5, then 10, then 30 per injection the animals could be made to display a large amount of behavior leading up to each injection. Just as with food, there was a point at which too large a response requirement would produce erratic responding or failure to respond at all. If you wanted maximum performance from a rat pressing a lever for food, you don't fill its cage with rat chow for each press nor do you give the rat small specks of food for each press. The same with drugs: you can draw a nice curve showing how the rate of responding first increases and then decreases as you systematically increase either the dose of drug per press or the amount of food per press. Thus, the idea spread that drugs can act as reinforcers of behavior and that this might be the basis of what has been called psychological dependence.(10) Drugs like amphetamines and cocaine could easily be used as reinforcers in these experiments, and they were known to produce strong psychological dependence in humans. These results seemed to indicate that psychological dependence might be more important than physical dependence in narcotic addiction, and led people to examine the lives of addicts from a different perspective. (9) Stories were told of addicts who occasionally stopped taking heroin, voluntarily going through withdrawal so as to reduce their tolerance level and get back to the lower doses of drug they could more easily afford. When we examine the total daily narcotic intake of most current addicts, we se that they do not have large habits and that the agonies of withdrawal they experience are probably more like a mild case of intestinal flu. We have known for a long time that heroin addicts who go through either rapid or slow withdrawal in treatment programs have a high probability of returning to active heroin use. In other words, if all we had to worry about was addicts avoiding withdrawal symptoms, the problem would be a much smaller one than it actually is. Psychological dependence, based on reinforcement, is apparently the real driving force behind even narcotic addiction, and tolerance and physical dependence are less important contributors to the basic problem. This is what we will refer to as the more recent view of addiction. In this text we have not gone so far as to redefine the word addiction itself in terms of psychological dependence, because that might simply lead to more confusion at this point. For now it is probably better to leave addiction undefined and to use the more specific terms as defined. Now that we have a better understanding of some of the basic forces driving addiction, it is clear that addiction is a muddy term, in part because it doesn't describe a single process. There is no such thing as "the" basis for addiction, because addiction is just a convenient term for the fact that some people (and other animals) develop strong patterns of behavior that are motivated by drugs. However, not all people who are exposed to narcotics or to alcohol do develop such strong drug-motivated behavior patterns. We can again turn to animal experiments to give us an idea of one type of controlling variable. In the standard drug self-administration experiment, the rats or monkeys are housed in a small cage with nothing much to do except press the drug- producing lever. Under those circumstances it is easy to demonstrate that some drugs are powerful reinforcers. But what if there are other, more "natural" reinforcers available? In one series of experiments, rats were allowed to drink a morphine solution, either when they were isolated in a small cage or when they were living in a large, complex "Rat Park" with other rats of both sexes. The rats in Rat Park did not increase their morphine consumption very much, whereas the isolated rats did drink more and more morphine as the days went by.(11) This indicates that the reinforcing effect of a drug may have to compete with other reinforcers in most natural settings and may help to explain why many people who are exposed to addicting drugs do not become addicted. An interesting book _The Meaning of Addiction_, examines historic views of addiction and reviews information that points to the fact that these compulsive behaviors that we call addiction, far from being easily characterized, uniform patterns of behavior, reflect much of the variety that is seen with other forms of human behavior.(12) The exact manner in which addiction does or does not appear in each individual depends on that person's history, personality, and the social and economic setting, just as with other behaviors. The closest thing to an "official" definition of these problems comes from the American Psychiatric Association's Diagnostic and Statistical Manual (DSM III-R). This manual describes "psychoactive substance dependence," which includes tolerance and physical dependence among its criteria, and "psychoactive substance abuse," which is based principally on behavioral symptoms (see box). These definitions are meant to be applied to patterns of use once called "drug addiction" and to another controversial term, "alcoholism." In other words, the "disorders" are considered the same, whether the substance is alcohol, heroin, cocaine, tobacco, or some other psychoactive substance. [Box:] Diagnostic criteria for psychoactive substance dependence A. At least three of the following: 1. substance often taken in larger amounts or over a longer period than the person intended 2. persistent desire or one or more unsuccessful efforts to cut down or control substance use 3. a great deal of time spent in activities necessary to get the substance (e.g., theft) taking the substance (e.g., chain smoking), or recovering from its effects 4. frequent intoxication or withdrawal symptoms when expected to fulfill major role obligations at work, school, or home (e.g., does not go to work because hung over, goes to school or work "high," intoxicated while taking care of his or her children), or when substance use is physically hazardous (e.g. drives when intoxicated) 5. important social, occupational, or recreational activities given up or reduced because of substance use 6. continued substance use despite knowledge of having a persistent or recurrent social, psychological, or physical problem that is caused or exacerbated by the use of the substance (e.g., keeps using heroin despite family arguments about it, cocaine- induced depression, or having an ulcer made worse by drinking) 7. marked tolerance: need for markedly increased amounts of the substance (i.e., at least 50% increase) in order to achieve intoxication or desired effect, or markedly diminished effect with continued use of the same amount. NOTE: the following items may not apply, to cannabis, hallucinogens, or phencyclidine (PCP): 8. characteristic withdrawal symptoms (see specific withdrawal syndromes under Psychoactive Substance-Induced Organic Mental Disorders) 9. substance often taken to relieve or avoid withdrawal symptoms B. Some symptoms of the disturbance have persisted for at least one month or have occurred repeatedly over a longer period of time. Diagnostic criteria for psychoactive substance abuse A. A maladaptive pattern of psychoactive substance use indicated by at least one of the following: 1. continued use despite knowledge of having a persistent or recurring social, occupational, psychological, or physical problem that is caused or exacerbated by use of the psychoactive substance 2. recurrent use in situations in which use is physically hazardous (e.g., driving while intoxicated) B. Some symptoms of the disturbance have persisted for at least one month, or have occurred repeatedly over a longer period of time. C. Never met the criteria for Psychoactive Substance Dependence for this substance. Adapted from the Diagnostic and Statistical Manual, third edition, revised 1987 by the American Psychiatric Association [close box] References: (9) NIDA Research Issues No 26, Guide to Drug Abuse Research Terminology, DHHS Publication No (ADM) 82-1237, Washington DC, 1982, US Government Printing Office. (10) Kelleher RT and Goldberg RS: Control of drug taking behavior by schedules of reinforcement, Pharmacological Reviews 27:291-299, 1976. (11) Alexander BK and Hadaway PF: Opiate addiction: the case for an adaptive orientation, Psychological Bulletin 92:367-381, 1982. (12) Peele S: The meaning of addiction, Lexington, Mass. 1985, DC Heath & Co. [excerpt ends] From: DRUGS, SOCIETY, AND HUMAN BEHAVIOR, Oakley Ray and Charles Ksir. Saint Louis: Times Mirror/Mosby College Publishing, 1993.