Is addiction that involves psychoactive drug-taking (for example, heroin dependence) the same as addiction that does not involve drug-taking (such as excessive shopping)? How can we distinguish the recurring central activities of daily life from the habitual and repetitive behavior patterns that rise to the level of addiction? In the absence of independent criteria to serve as a guide, making these distinctions can be as difficult as separating twilight from dusk or late winter from early spring. This article will explore the nature and meaning of addiction and consider some of the conceptual confusion often associated with this construct.

From substance abuse to shopping, running, game-playing, working, eating "chips" or carrots), drinking water to intoxication, having sex, and excessive computer use, social observers have applied the notion of addiction to many and varied human activities. Traditionally, however, addiction has most often been applied to substance-using behavior patterns; more recently, social observers began to apply the concept to activities that do not include the use of psychoactive drugs. In both circumstances, when addiction is present, then the consequences of the activity are, in part, adverse. Surprisingly, addiction also provides positive effects for the sufferer, particularly early in the process. For example, an addiction can distract someone from more painful emotional problems or provide an identity that organizes everyday experiences. The combination of positive and negative consequences is one reason why addictive behaviors are very difficult to change.

The negative consequences of addiction typically include social, psychological, and biological harms. The biological consequences often-but not always-include the emergence of neuroadaptation. Neuroadaptation is the technical term for the tendency to increase the dose level of a drug to experience the same subjective effects as with a lower dose before and also to experience a stereotypical pattern of discomfort upon stopping the drug use. For example, heroin users tend to increase their dose to get the same level of intoxication experienced previously at a lower dose, or get sick when they stop using the drug.

Earlier applications of the term "addiction" were less onerous than our current views. When scientists began to consider the matter of behavioral addictions that did not require drug taking, the construct of addiction became more plastic and complex. For example, clinicians have noticed that, in the absence of psychoactive substance use, excessive behavior patterns such as pathological gambling can stimulate the development of tolerance and withdrawal typical of drug dependence. This observation raises important questions about the nature and meaning of addiction.

ON THE MEANING OF ADDICTION

Addiction is a lay term, though it is often used by scientists. "Dependence" is a more scientific construct, occasionally used by lay people. While there are many working definitions of addiction, the essence of the construct has remained elusive. Consequently, addiction remains an imprecise lay concept. Addiction has not yet been welcome in the contemporary diagnostic manuals that organize and define psychiatric and other diseases. Recognizing the semantic problems associated with the addiction construct, Vaillant (1982) suggested that, instead of seeking a strict operational definition, we should think of alcoholism as we do mountains and seasons: you know these things when you see them.

As we approach the twenty-first century, many important addiction-related issues remain unresolved. However, it seems to me that researchers and clinicians alike still are uncertain about what they mean by the concept of "addiction." Absent this understanding, neither scientists nor clinicians will know what to do with either the neurobiological or clinical discoveries of the future. While this may seem like a simplistic conceptual concern, I am quite certain that there is nothing at all simple about it.

Without a clear definition of addiction, researchers will continue finding it very difficult, for example, to determine "addiction" prevalence rates, etiology, or the necessary and sufficient causes that stimulate recovery. Without a precise definition of addiction, clinicians will encounter diagnostic and treatment-matching difficulties. Satisfactory treatment-outcome measures will remain elusive. Without an agreed-upon definition of addiction, social-policy makers will find it difficult to establish regulatory legislation, determine treatment needs, establish health care systems, and promulgate new guidelines for health care reimbursement.

For scientists, the concept of addiction represents a troublesome tautology. This tautology has contributed to keeping an addiction classification from entering the diagnostic nomenclature. Therefore, the notion of addiction remains primarily a lay concept, and a very popular one indeed. The tautology operates like this: when observers notice adverse consequences, stimulated by repetitive behavior patterns, apparently occurring against the actor's better judgment, they often infer the presence of addiction. However, even this inference is not without complexity. For example, "The problem is that there is no independent way to confirm that the 'addict' cannot help himself, and therefore the label is often used as a tautological explanation of the addiction. The habit is called an addiction because it is not under control, but there is no way to distinguish a habit that is uncontrollable from one that is simply not controlled" (Akers, cited in Davies 1996, p. S41).

Scientists and treatment providers are not the only ones with a problem when the meaning of addiction is fuzzy. The average person will find that, without a clear definition of addiction, the distinctions among an array of human characteristics will remain blurred (for instance, interest, dedication, habit, attention to detail, obsession, compulsion, and addiction). Finally, the contemporary conceptual chaos surrounding addiction must be resolved to clarify the similarities and differences-if these exist-between process or activity addictions (such as computer addiction, pathological gambling, excessive sexual behavior) and substance-using addictions (such as heroin or alcohol dependence).

In response to the preceding comments, some will argue that they indeed have an explicit definition of addiction. Because these individuals have a model, they incorrectly assume that they also have the truth, that their model is preeminent and precise. In addition, they incorrectly assume that their model will work for the rest of us if only we could see the light. However, this is the problem with worldviews, in general, and scientific paradigms in particular: as a conceptual schema organizes one person's thoughts, simultaneously it blinds that person to alternative considerations. Rigid thinking sets in, and science fails to progress until anomalies challenge the conventional wisdom.

DISTINGUISHING USE, ABUSE, DEPENDENCE, AND ADDICTION

Without a consensual definition of addiction, clinicians and social-policy makers often are left to debate whether people who use drugs also "abuse" drugs. Treatment programs regularly mistake drug users for "abusers"; both of these groups are readily mistaken for those who are drug dependent. Too often the result is unnecessary hospitalization, increased medical costs, and patients who learn to distrust health care providers. Alternatively, without a precise definition of addiction, some people fail to receive the care they require. As a result of these complex conditions, practice guidelines in the addictions are equivocal, and health care systems fall into management and reimbursement chaos.

Even under most established constructions of addiction, not all drug-dependent patients evidence addictive behavior. (Although a full discussion of this matter is beyond the scope of this article, it also is important to note that not all people with addiction are impaired in every aspect of their daily lives.) For example, in most civilized countries, under nearly every traditional circumstance, people who are nicotine-dependent do not evidence addiction. When tobacco is recast as a socially or legally illicit substance, however, addictive behavior patterns have emerged. Complicating matters, physical dependence is not always necessary for the notion of addiction to apply. For example, upon stopping, pathological gamblers who do not use alcohol or other psychoactive drugs often show physical symptoms that appear to be very similar to either narcotics, stimulant, or poly-substance withdrawal. Perhaps the patterns and experience of excessive behaviors are more important than the object of these acts.

ADDICTION WITH AND WITHOUT DEPENDENCE: SUBSTANCES & PROCESS

If addiction can exist with or without physical dependence, then the concept of addiction must be sufficiently broad to include human predicaments that are related to either substances or activities (that is, process addiction). Although it is possible to debate whether we should include substance or process addictions within the kingdom of addiction, technically there is little choice. Just as ingested substances precipitate impostor molecules vying for receptor sites within the brain, human activities stimulate naturally occurring neurotransmitters. The activity of these naturally occurring psychoactive substances probably will be determined as the mediating cause of many process addictions.

THE NEUROCHEMISTRY OF ADDICTION: SHIFTING SUBJECTIVE STATES

If addiction can exist both with and without physical dependence, then we may be able to advance the field by considering the objects of addiction to be those things that can reliably and robustly shift subjective experience. The most reliable and robust "shifters" hold the greatest potential to stimulate the development of addictive disorders. In addition, because the strength and consistency of these activities to shift subjective states vary among individuals, scientists have been unable to predict with accuracy who will become addicted. Nevertheless, psychoactive drugs and certain activities correlate highly with shifting subjective states because these activities reliably influence and change emotional experiences. Consequently, psychoactive drug use and certain other behaviors (for example, gambling) tend to be ranked high among the activities often associated with addictive behaviors.

The most common conceptual error committed by clinicians, researchers, and social-policy makers is to think that addiction resides as a latent property of an object (for instance, a drug or game of chance). Conventional wisdom, for example, refers to "addictive drugs" or "addictive gambling." However, addiction is not the product of a substance, game, or technology, though each of these things has the capacity to influence human experience. Experience is the currency of addiction. Therefore, when a particular pattern of behavior can reliably and robustly change emotional experience, the potential for addiction emerges. Addiction is the description of a relationship between organisms and objects within their environment; it is not simply the result of an object's attributes, Consequently, the causes of addiction are multifactorial.

OBJECTS OF ADDICTION: CAUSE, CONSEQUENCE, OR RELATIONSHIP

To this point, I have implied that simply using drugs or engaging in certain activities does not cause addiction. Now let me be more explicit: from a logical perspective, the objects of addiction cannot cause addictive behavior patterns. This is a form of teleological thinking that contributes much to contemporary conceptual chaos in addiction theory. To illustrate, if psychoactive-drug using were a necessary and sufficient cause for addiction, then addiction would occur every time this pattern of drug using was present. Similarly, if drug using were the only necessary and sufficient cause for addiction, addictive behaviors would be absent every time drug using was missing. However, as I have already explained, tolerance, withdrawal, and adverse consequences of excessive behaviors are often present when drug using is absent. In addition, people often exceed their drug-using limits and lose a modicum of self-control without experiencing addiction. Therefore, drug using is neither a necessary nor a sufficient cause of addiction.

Furthermore, as I have suggested, drug using may not even be the primary cause of addiction. Even though drug using is highly correlated with addiction because psychoactive substances reliably shift subjective experience and alter neurochemistry, drug taking does not cause addiction. As in the case of pathological gambling and excessive sexual behaviors-which do not fall within the domain of obsessive-compulsive disorders-addiction can exist without the presence of drug taking. This observation provides insight into the necessity of considering a more complex relationship between people who might develop addiction and the object of their dependence.

It is the relationship of the addicted person with the object of his or her excessive behavior that defines addiction. It is the confluence of psychological, social, and biological forces that determines addiction. No single set of factors can define addiction precisely. Unfortunately, the concept of relationship also is difficult to define. Therefore, until experience provides more insight into the synergistic nature of these factors and helps us determine the interactive threshold(s) that may apply, we are forced to operationalize addiction so that researchers, clinicians, and policy makers can share a common perspective.

GUIDELINES FOR IDENTIFYING CONTEMPORARY ADDICTIONS

In spite of the conceptual complexities associated with the construct of addiction, a variety of devices can help people determine if they might require a more thorough and professional evaluation. These screening instruments can help researchers and clinicians avoid confusion by offering a handy scheme for identifying the potential presence of addiction. Perhaps the simplest scheme for identifying the possible existence of addiction is the 3 Cs:

*Behavior that is motivated by emotions ranging along the Craving to Compulsion spectrum; craving can range from a mild desire to an overwhelming impulse to act. A compulsive behavior is a powerful repeating pattern of action.

*Continued involvement with the drug or activity in spite of adverse social, psychological, or biological consequences;

*Loss of Control, that is, a subjective sense that one no longer can control one's behavior.

While these three characteristics can provide effective tools for clinicians or others who are screening for an addictive disorder, they provide a blunt instrument rather than a precise guide to the diagnosis of addiction. More precise screening and diagnostic tools also are available (for example, the Addiction Severity Index and the Michigan Alcoholism Screening Test) to clinicians. However, these standards remain underused, perhaps because clinicians remain uncertain of, and ambivalent toward, the construct they want to measure.

Addictive behaviors also tend to be ego-syntonic, particularly early in the development of the addiction. Ego-syntonic behaviors are experienced as consistent with a sense of self and are not perceived to be the cause of personal problems. In fact, most addictions emerge from a positive experience (winning a bet, relieving psychological or physical discomfort by ingesting drugs). Other psychiatric illnesses tend to be experienced as ego-dystonic, or ego-alien. Ego-dystonic states are experienced as an "otherness," as if a renegade part of oneself were taking control against one's will or directing behaviors toward undesirable ends. Clinicians often can distinguish obsessive-compulsive disorders from addiction by the presence of ego-dystonic thoughts and subjective states (Shaffer 1994).

CONCLUSIONS

If addiction can exist both with and without ingesting exogenous drugs-as is the case with gambling-then the concept of addiction must be sufficiently broad to include human predicaments that are related to either substances or activities (process addiction). Although it is possible to debate whether we should include both excessive substance and process disorders within the conceptual domain of addiction, technically there is little choice. Just as exogenous substances precipitate impostor molecules vying for receptor sites within the brain, other activities (that is, not related to drug taking) also can stimulate the activity of naturally occurring neurotransmitters. As neuroscience researchers improve our understanding of the biochemistry of the brain, the effects of these naturally occurring psychoactive substances probably will be determined as the mediating cause of many process addictions.

Finally, if the concept of addiction is to inform scientific research and clinical treatment programs, then it must be reliable and valid. Clinicians and scientists must learn to predict the onset and development of addiction from independent factors. Absent these developments, addiction will remain a fuzzy concept that can confuse policy makers and perplex the criminal justice system. Without clear criteria, addiction will be invoked to provide a ready excuse for excessive behaviors that people are unwilling to change. Further, addiction will not be applied when it should be used. Precisely because observers fear that they will provide an excuse for unacceptable behaviors, people who indeed are struggling against overwhelming impulses to act will not be considered suffering with an addiction. Without more clarity and precision, it will remain difficult to distinguish between someone experiencing an over-whelming impulse to act in a self-destructive way and someone who is simply unwilling to control his or her destructive impulses to act. As a result, clinicians and the criminal justice system alike will punish some people who need treatment and treat some people who really need censure.
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Howard J. Shaffer, Ph.D., is an associate professor and the Director of the Division on Addictions at Harvard Medical School. In addition to research and private practice activities, he consults internationally to a variety of organizations in business, education, human services, and government. His major research interests include the social perception of addiction and disease, the philosophy of science, impulse control, as well as compulsive behaviors, adolescent gambling, and the natural history of addictive behaviors. Dr. Shaffer's books include Quitting Cocaine: The Struggle Against Impulse with Dr. Stephanie Jones, and Compulsive Gambling: Theory, Research & Practice, edited with Dr. Blase Gambino, Sharon Stein, and Thomas N. Cummings. This article was adapted from several recent works by Shaffer (Shaffer 1996; Shaffer l997a; Shaffer 1999).

The preparation of this article was supported, in part, by a Center for Substance Abuse Treatment grant (#1U98TI00846) and a grant from the National Center for Responsible Gaming.
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References provided in the original paper may be obtained from National Forum, Fall 1999 v79 i4 p9.

Also, see
Futures at Stake: Youth, Gambling, and Society (The Gambling Series)
by Howard J. Shaffer (Editor), et al (Hardcover - September 2003)