~ An Exploration of What We Do ~

~ The Usefulness of General Theories of Addiction ~



Steven L Booker
Department of Psychology
University of Sydney
Synopsis

In recent years health and lifestyle issues have become increasingly topical. Media campaigns centering on changing health related behaviours such as smoking and drug use are frequent, often emphasising quite graphically the results of not adopting healthy lifestyles. One result of this in the community is an increase in anxiety directed toward health issues. This process is examined with reference to the issue of drugs and addiction, and it is argued that it can bias scientific reasoning. "Addiction" is a concept which until recently was only applied to narcotic use that was considered to be out of the addict's control. However, there is a trend in modern Psychological theory to equate behaviour which is descriptively but not functionally similar to drug addiction, as addictive. Many behaviours which are repetitive and toward which persons exhibit loss of control but which do not involve drugs, such as gambling and computer game playing, are currently being reclassified as addictions by some areas of Psychology. In some cases these behaviours are considered to be "addictions", even though the neural mechanisms proposed to underlie them can be shown to be different to the those associated with narcotic use. In other cases no data has been gathered and the behaviours appear to have been assumed to be addictions on the basis of their presenting symptoms, that is, on a descriptive basis alone. In an attempt to clarify the meaning of the term "addiction" , a distinction is made between two types of addiction theory. "Pharmacological" theories focus upon changes in brain structure and function due to repeated ingestion of drugs, which affect brain reward pathways directly. For pharmacological theories, "addiction" refers to the causal role these changes play in individuals susceptible to addiction. Conversely "General" theories of addiction define addiction by describing its behavioural manifestations alone, without reference to its effects upon brain function. It is argued that only substances or behaviours which can be shown to directly affect brain reward pathways should be considered as having addictive potential.

Introduction

Although my focus in this paper is "drugs and addiction", it is necessary for me to provide a background to the discussion. This is because I am writing not only about a matter of Psychological interest, but trying to show how it has been affected by the community as a whole. The issues of drugs and addiction are not purely in the realm of medicine or psychology. They are to a large extent social and political issues. Thus before I begin a detailed analysis of the Literature on addiction, I wish to make some general opening remarks on how I believe society, or the "lay" person is contributing to the Psychological study of addiction.
In recent decades, western nations have exhibited an increasing interest toward health related behaviours. These may be defined as behaviours which have some (usually long-term) adverse effect on a person's health, physical and/or psychological. One area of popular culture in which this is particularly evident is the mass media. Media campaigns have been directed toward health issues including smoking, cholesterol reduction, skin cancer, sexual behaviour, nutrition, and a variety of other behaviours. Popular "talk show" programs often devote entire series to issues like these, and the dramatic nature of these programs has helped to popularise concern over health and lifestyle issues.
In many countries groups like the American Medical Organisation, have been actively working to promote health consciousness in the community. The public has been encouraged to take an active role in the maintenance of their health status, rather than only worrying about it when they become sick.
Partly as a result of these influences, health issues have become topical, being widely and openly discussed in popular culture. People appear to be more aware of the ways in which they are benefiting, and the ways in which they are harming their health. As is to be expected of public, or perhaps any debate, the issues have not been dealt with in a completely rational manner. Peoples' emotions, biases, and life experiences all go together to create their viewpoint about any health issue. Consider tobacco smoking as an example. Smoking a cigarette in a public place has almost become a political statement in the 90's. The issue of smoker's rights vs the evidence for the dangers of passive smoking have caused tension in many work and public places. What is clear is that this debate is not just about the scientific facts surrounding smoking and addiction. It is also about moral and ethical questions such as personal liberty - thus the smoker often invokes his/her right to smoke. Addiction theory is similarly being affected in this way. We can understand this process better by examining these non-scientific influences on the addiction debate.
One example is media campaigns, which often play upon the viewer's emotions as a way of attempting to foster change of health behaviours. In conjunction with this, graphic illustrations of the results of failure to change to a more healthy lifestyle are often used. One example is a recent anti-smoking campaign on Sydney Buses which bears the message : "If you think it's agony to give up smoking, you should see what it's like if you keep going" and the recent anti-alcohol advertisements on Sydney television that show drunken people getting taken to hospital after having lost control over their alcohol consumption, and the drastic effects that this has on their lives. Thus among other strategies, these campaigns are attempting to use fear to change behaviour. As well as including a cognitive component - ie. the information that smoking can cause lung cancer - they also include an evaluative component, or an attitudinal component - ie. the idea of how bad you will feel if a similar type of disaster occurred to you.
Of course, empirical work in Social Psychology to do with attitudes and behaviour change is part of the reason that these campaigns are as they are. It has been demonstrated that people are more likely to change their behaviour if confronted with reasons for changing their feelings and attitudes toward it, rather than just their ideas about it. Nevertheless I argue that as a result of this increased media pressure, and the public concern over health issues that it leads to, many people have begun to exhibit increased anxiety toward their health status. Behaviour which has been unquestioned in relation to its effects on health in the past is in many cases coming under increased scrutiny. Sometimes this scrutiny is warranted, as it may be argued is the case with excessive alcohol consumption which has been proven to lead to damage to many of the body's major organ systems. There are however other examples, where the concern could only be described as "hysterical", or hypercondriac. Video game playing is a good example of this. Questions such as does Video game playing even constitute a health related behaviour aside, it appears that video game playing has recently been the subject of Psychological research whose purpose has been to ask the general question :"Is computer game playing bad for Psychological development". The point is that for many years, computer game playing has been regarded as a recreational activity, not a vice. Yet it seems that now it has been noted that this activity is descriptively similar to addictive behaviours, in that it is repetitive and cause some people to lose control over their playing behaviour, it is being thought of as an addiction.
Why this increase in concern over health issues has occurred is beyond the scope of this paper. As is any quantitative data describing the extent of the increase. But assuming these assertions are an adequate, if somewhat general description of the situation, I wish to move on to an analysis of one effect that this anxiety over health issues is having on psychological theory. The topic I wish to discuss concerns drugs and the concept of "Addiction"

Defining Behaviours as Addictions

Drug use both legal and illegal has Shared this increase in popular attention, especially since the 1940's. Although recreational drug use has existed for many thousands of years, wide scale attempts to regulate and stop this practice are a relatively new phenomena. Billions of dollars have been spent by law enforcement agencies to stop the production and distribution of drugs, and drug use is often considered as one of the major sociological problems that confronts many societies throughout the world. It is not surprising, therefore, that this is one health issue that is commonly discussed in popular culture. Associated with discussions of drug use, and whether it is a good or bad thing, one usually finds some reference to the notion of "Addiction".
The term "addiction" is not neutral - it has connotations of sickness, or abnormality. Even when used in a purely Psychological sense it implies some type of disorder - as do the terms that are associated with it (ie "substance abuse") . In fact this is why arguments against drug use, or drug legalisation often invoke the idea that "drugs are bad because they are addictive." Addiction is seen to be a bad thing, and drugs, which can produce addiction, are thus also considered to be bad.
The problem for Psychology arises when the general anxiety toward health related behaviours noted above, leads to comparisons between drug addiction and other types of repetitive behaviour which resemble drug addiction. One area where this has occurred is gambling. As far as DSM IV is concerned, gambling is an addiction,, and the criteria used to diagnose gambling, match many of those used to define addictive behaviour. These include withdrawal, tolerance, and loss of control. (Walker 1988)
To some extent, our society, and some elements of Psychology are becoming what might be described as hypochondriac, for lack of a better term. Considering people who play video games, or gamble compulsively as "addicts", and their behaviour as "addiction" is to reclassify them as "sick" or "disordered". There is no doubt that a compulsive gambler who has lost large amounts of money, or their house, and who is facing recrimination from a spouse or family, is not completely Psychologically "healthy". Yet calling this behaviour gambling seems to serve no purpose other than to ostracise the gambler. It also raises questions such as if gambling is an addiction, where is the line to be drawn? As I describe below, some Psychologists have argued that dependent love styles can be considered addictive. If we follow this line will it not be long before we are forced to accept ideas like "breathing is addictive"?
More importantly, considering gambling (for example) to be addictive is to ignore scientific definitions and understanding of what addiction is. It is to favour description over explanation. The term "addiction", as it is understood by neuroscience and pharmacology, means more than just a process which is descriptively similar to drug addiction. In fact, it means that the processes involved in causing this repetitive behaviour are of the same nature. Equating gambling with drug addiction seems to be to ignore the fact that studies of brain function during gambling, and drug use produce two quite different sets of data (see below).
This move toward describing repetitive behaviours as "addictive" seems to come, partly, out of a desire to classify and thus better understand these behaviours. Certainly, when one looks at the way in which clinical psychology attempts to classify and describe the presenting symptoms that clients manifest in treatment sessions, it becomes clearer why this move should be occurring in Psychology. Consider the DSM IV. Diagnosis of client problems occurs by cross referencing the presenting symptoms with a list which describes all the symptoms that have been manifested by other clients experiencing a similar problem. By being able to classify clients as having disorder A, or disorder B, the clinician feels that he/she has an idea of where to start, of how to help this client, and treatment strategies can begin. Thus treating problem gamblers, or video game players, for example, as though they would benefit from the same types of therapy used to help drug addicts- ie. using techniques such as cue-exposure or various types of cognitive training to increase self-control, allows the therapist to have a measure of control over these problems, and to begin to help the client. I should note at this point that I realise the picture I have given above of clinical psychology is greatly oversimplified, and perhaps unjust. Rather than being a criticism of this area of Psychology, it is meant to serve as an example of the types of human process (ie. the desire to help clients in need) which can sometimes bias scientific reasoning.
By examining the historical development of the concept of "addiction", I will show how it has progressed from a moral to a scientific model of certain behaviours. Then I will argue that Psychological theories which regard behaviours that do not involve drug use, as addictions, are really a return to moral concepts of addiction. Such "General" theories of addiction threaten the usefulness of the term and should be rejected. In order to make this discussion more meaningful I should briefly make some remarks about terminology. When I write of the "Medical" or "scientific" or "pharmacological" view of addiction, I am talking about "addiction" as it is viewed from a scientific viewpoint. A viewpoint which considers empirical data from comparative studies using laboratory animals, and human data. Conversely, when I refer to the "Moral" or "General" view of "addiction" I am talking about addiction as it is viewed from a "common sense" or "lay" viewpoint- a viewpoint which is primarily concerned with categorising and describing behaviour which appear similar under the term "addiction" without being concerned about the causes of this behaviour.

History of the addiction concept.

Scientific models usually follow the Zeitgeist rather closely. As we have seen, the public image of mankind has been changing from one that emphasised free will and morality to more deterministic, non-moral formulations. (Krivanek 1988 p46)

In the above quote, Krivanek, who is speculating about the possible causes of the change from the moral to the medical model of addiction, has hit upon an important trend. Historically, addiction models have been largely moral. They regarded any behaviour or substance which a person repeatedly indulged in as "addictive". The causes of addiction were held to be a weakness of will on the part of the addict. Thus Sonnedecker (p18 in Peele 1990 p207) writes:

Earlier, although some theorists described narcotic addiction this does not mean they ..... held any conception distinguishing addiction to opium from, say, sugar plums.....In this period between the late 16th and the early 19th centuries......'to addict' commonly meant 'to devote, give up, or apply habitually to a practice' such as to a vice......[those using the term] meant: it's a bad habit.
(brackets added by Peele 1990)

What is important to note here is that because the causes of addiction under this view were completely intra-individual, any habit, any behaviour which was repetitive could be called addictive.
Now as Krivanek notes, philosophical theories of behaviour have been changing from free-will to deterministic conceptions. And concomitant with this change, medical models of addiction from the 1900's onwards began to regard addiction as a deterministic process. A process which resulted from neuroadaptions (ie. changes in receptor frequency and/or distribution) caused by repeated self administration of narcotics. Although the medical model assumes that there are individual differences in susceptibility to addiction, it places emphasis on the properties of drugs themselves in producing addiction. As a result, only certain substances which can be shown to lead to neuroadaption, have been considered "addictive" by the medical model.
In recent decades, general theories of addiction have become increasingly popular in Psychology. The moral model of addiction described above may be seen as an historical precursor to these general theories, because both attempt to explain addiction in psychological rather than physiological terms, and both consider addiction to be caused by intra-individual factors alone. General theories of addiction (eg. Peele 1975, Jacobs 1987) although not essentially moral in nature, argue that for certain people who are predisposed to addiction, any activity - even gardening - can be addictive. I will consider the medical model, and the general model of addiction in turn, and argue that:
  1. The medical model regards addiction as much more than simply repetitive behaviour, and therefore makes the term "addiction" useful;
  2. The general theory of addiction although not solely the idea that addiction is repetitive behaviour, is much closer to this idea than the medical model. All it adds is the idea that the addict has become psychologically dependant upon the behaviour for positive affect, or escape from stress;
  3. Attempting to conceive of repetitive behaviours that produce psychological dependency as addictive weakens the usefulness of the term "addiction", because psychological dependency is qualitatively different from addiction;
  4. And therefore, a line should be drawn such that only addiction to substances which can be explained by the medical model should be thought of as addictions.

The Pharmacological Model of Addiction

Since the beginning of the twentieth century, the concept of "addiction" has become focused on explaining the repeated self administration of drugs. I must first define exactly what the term "drugs" means. It is unclear because it contains moral overtones. Its everyday usage sometimes equates with "narcotic substances which are illegal", and this has prompted some to argue that nicotine and alcohol for example, are not "drugs". Further, general theories of addiction argue that substances such as chocolate and spicy foods should be considered as drugs capable of producing addiction. In order to avoid these inconsistencies, we will adopt Walker's (1992) distinction between drugs and pleasurable activities/substances. Walker (p 177) notes that:

.....drugs act centrally on the reward system in the brain whereas all other pleasurable activities....work through the sensory organs and....through significant areas of the neocortex. The actions of drugs such as Heroin and Cocaine are reinforcing because they stimulate the production of dopamine directly.

Walker (1992) calls the medical model of addiction which focuses on the physiological explanation of drug self administration the "study of the pharmacology of the craving for drugs" (page 177) This paradigm will henceforth be referred to as the pharmacological model of addiction, and will be considered to represent the most updated and scientific version of the medical model. Specifically this model considers any substance which can be shown to produce craving through the process of neuroadaption, to be addictive in individuals who exhibit susceptibility to addiction, whether this susceptibility is brought about due to environmental or genetic influences.
Let us start with the first half of the statement above: that drugs are addictive due to their potential to cause neuroadaption. The statement actually consists of two related ideas. The first is an idea about what drugs do to brain function - it is the idea that drugs stimulate brain reward pathways. The reward pathway most often held to be responsible for addiction is the mesocorticolimbic Dopamine (DA) system. The pharmacological model is based upon observations that in rats and humans, drugs produce the saturation of DA receptors in the mesocorticolimbic DA system. Koob (1992) provides a representative example of the assumptions made by the pharmacological model in based on these observations. He writes that the mesocorticolimbic DA system is:

.....an interface between the midbrain and the forebrain.....[and] has been hypothesised to modulate the activity of the ventral striatum, a brain region thought to be involved in converting emotion into motivated action and movement. The mesocorticolimbic Dopamine system has been implicated in drug reinforcement. (page 177 brackets added)


In fact DA has been implicated in addiction to Cocaine, (Kuhar et.al. 1991, Woolverton and Johnson 1992) Alcohol, (Samson and Harris 1992) the opiates and amphetamines (Koob 1992). Further, for substances whose ingestion proves difficult to link to DA release, evidence has been found which suggests that their reinforcing qualities are due to other neurotransmitter systems. Abood and Martin (1992) report data which suggests that Marijuana addiction is mediated by a naturally occurring cannabinoid receptor. While Koob (1992) notes that the GABA neurotransmitter plays a role in the reinforcing properties of barbiturates and benzodiazepines :

At the Electro physiological level GABA produces post synaptic inhibition. Barbiturates, benzodiazepines and ethanol have been shown to potentiate this inhibition.....ethanol, barbiturates and benzodiazepines all have classic sedative/hypnotic actions....which include euphoria, disinhibition, anxiety reduction, sedation and hypnosis....This anxiolytic or tension reducing property of sedative/hypnotics may be a major component of their reinforcing actions.

The second idea has to do with the effect of drugs upon brain structure - it is the notion that following repeated activation of the DA reward pathway in the nucleus accumbens, the DA system adapts to the stimulation producing behavioural effects such as tolerance, and sensitisation to the drug's effects (Robinson and Berridge 1993). The adaptation is assumed to occur due to changes in DA receptor frequency and sensitivity (ie. changes in structure)
Therefore the first reason why the pharmacological model considers addiction to be more than simply the repetition of behaviour, is because it demonstrates how drug seeking behaviour causes changes in brain structure and function. Addiction is not simply the repetition of drug ingestion- it produces changes in the organism at a basic physiological level.
A second reason concerns the pharmacological model's assumption that not all individuals who exhibit repetitive drug ingestion will become addicts.
To examine this, we turn to the second half of the statement- that individual differences in susceptibility play a large role in addiction. Krivanek (1988) notes that one of the flaws of the early medical model of addiction was that it considered drugs to be automatically addictive. Anyone who used heroin, it was theorised, would inevitably become addicted because heroin was a drug of addiction :

In the 1920's the disease model of opiate dependence was very much that proposed by Rush for alcohol: these drugs had an inherent property of producing uncontrollable craving, and once begun, the disease inevitably progressed. (page 33)

Although this inevitability of addiction was challenged by the Alcoholics Anonymous concept of individual vulnerability, the idea that the properties of drugs alone were what caused addiction was still prominent in the 1950's. The 1952 World Health Organisation expert committee on drugs "described drugs in its 'addiction producing' category as causing an irresistible need 'always and in all individuals'" (Krivanek 1988 p 33).
However in the last three decades of addiction research, this assumption has been challenged. Firstly research has been conducted which shows that many individuals who use what were thought to be "addiction-producing substances" do not become addicted, even though they may use these substances for a very long time. Shiffman (1991) has documented numerous cases of what he calls "tobacco chippers." These are individuals who smoke cigarettes at least four days a week- but at levels too low to maintain steady state blood-nicotine levels (less than 5 cigarettes per day). Shiffman noted that the individuals that he studied had exhibited this pattern of smoking behaviour for an average of twenty years, yet seemed free from nicotine dependence - when abstaining for two days no withdrawal symptoms were observed or reported.
Another example comes from Peele (1990) who notes work done by Robins et al.. (1980). Robins studied soldiers returning from Vietnam who were known heroin addicts, and concluded that :

Of all the men addicted in Vietnam [defined as prolonged heavy use and severe withdrawal symptoms lasting two or more days] only 12% have relapsed into addiction at any time since their return. (Peele p 212)

Even if it is argued that it was the extreme stress of war which produced these cases of addiction, this in no way reduces the force of the evidence that in this sample, 88% of users addicted to heroin, were later found to be non-users. This is because even though the returned soldiers were no longer being stressed by the war, they still possessed the neuroadaptions created by their drug use, and thus should have continued to use drugs. The fact that they did not suggests that they were individuals who did not possess genetic susceptibility to addiction. but were exhibiting addiction in response to environmental influences.
Generally speaking, epidemiological studies of drug use support the idea that most people who try drugs don't become addicted, because the proportion of people who experiment with drugs is always much larger than the proportion of the population who become addicted (Krivanek 1988). Although it should be noted that our measure of addiction rates is confounded by only being able to measure those who seek treatment. Further, surveys asking people to self report drug use are confounded because people are often scared to self report drug use. Nevertheless, it may be argued that addiction is more than the repetitive ingestion of drugs, because not everybody who ingests drugs repetitively becomes addicted.
The second type of research to do with individual susceptibility to addiction, has focused on discovering the neurobiological factors which predispose individuals to addiction. Perhaps the best known example of this is the debate currently in progress over the D2 (Dopamine) receptor gene and its possible causal role in alcoholism. A number of researchers have proposed the idea that in some individuals, this gene produces either decreased DA receptor sensitivity, or a decreased frequency of DA receptors. As a result, it is argued, these individuals turn to alcohol as a means of facilitating DA release, in order to self-medicate themselves. Blum et.al. (1988) reported that the D2 receptor gene was present in 60% of patients with severe treatment-resistant alcoholism, compared with 20% of controls. Although a meta-analysis by Gelertner et.al. (1993) suggested more conservative interpretations of Blum's work-namely that the effects were produced by sampling error and ethnic variation, case studies controlling for ethnicity (eg. Comings et al.. 1991) have suggested that the D2 gene acts as a modifier of substance abuse if not as a primary etiological agent. Although the findings are not conclusive, this research suggests that addiction is a complex interaction between individual susceptibility and the properties of drugs. In other words to the pharmacological model, "addiction" means more than the repetition of drug ingestion - it is a relation between the individual's biochemistry and a substance.
Now we may ask, why is the term "addiction" as it is defined by the pharmacological model useful? Firstly it specifies a set of empirically supported physiological assumptions about neuroadaption and resultant behaviour change that occur as a result of drug addiction. This makes the term useful because treatment strategies can be developed which are based on this empirical understanding of the process. Consider for example cue exposure treatment strategies for addiction. Briefly, these theories posit that one factor which can influence relapse in an addict, is exposure to environmental stimuli, or cues, that signal the presence of drugs. In fact cue exposure theory has been largely developed from research supporting the pharmacological model such as Robinson and Berridge's work (1993), which suggests that the perception of cues have effects on the DA network independent of drug ingestion, which causes craving to occur. The pharmacological model of addiction although far from perfect or universal, is relatively conceptually sound, and has empirical support at a physiological level. This is why it should not be diluted by attempting to combine it with general theories of addiction, which do not have this empirical support.

General models of addiction

...the first concerted attempt to present a systematic analysis of the common elements among different forms of addictive behaviours waited until the publication of 'Commonalities in substance abuse and habitual behaviour' (Levinson et.al. 1983).....The intent was to gather and evaluate relevant scientific evidence that might indicate the extent to which many aspects of excessive substance use and other habitual activities have common biological, psychological and/or social roots.....After balancing evidence supporting either similarities or differences among addictive forms of behaviour the editors concluded that 'In general scientific knowledge does not at present provide the basis for a comprehensive theory of excessive, habitual behaviour encompassing the available sociocultural, psychological and biological evidence' (Jacobs 1987, p42)


General models of addiction (eg. Peele 1975, Jacobs 1987, fuller et.al 1987) have become increasingly popular in contemporary Psychology. Generally speaking, these models have tended to view addiction as the process whereby an individual becomes psychologically dependant upon the continued repetition of a certain behaviour, to fulfil a Psychological need. For example Peele (1975) when discussing addiction to love writes:

We often say 'love' when we really mean, and are acting out, an addiction - a sterile ingrown dependency relationship, with another person serving as the object of our need for security. (Peele 1975 p 13)

From this definition, we can see that general models do not view addiction simply as repetitive behaviour. They add to this the idea that psychological dependency upon the behaviour is a necessary condition for addiction. General models would not consider breathing to be addictive, because it could not be argued sensibly that an individual is psychologically dependent upon it. General models also recognise the distinction between repetitive behaviour brought about by obsessive-compulsive disorder, and repetitive behaviour which the individual continues to exhibit because it is pleasurable.
However, these general models are much closer to arguing that addiction is simply repetitive behaviour than the pharmacological model discussed above. I will describe the features of the general model and show how they are incompatible with the more established pharmacological model.
Firstly, these models are descriptive rather than explanatory. They tend to be descriptive because the impetus for their development has come largely from the helping professions. Faced with people exhibiting dependency upon a wide range of behaviours and substances, all of whom exhibited a similar set of symptoms which can be generally described as impairment in personal and social functioning, the helping professions have sought a model which could make sense of these dependencies. The pharmacological model, although based on drug addiction, also describes individuals who exhibit impairment of social and psychological functioning due to their addiction. So, needing a model to deal with these psychological dependencies, the general theories were constructed on the medical drug addiction model. And the way a lot of these theories work is to begin by describing psychological dependency, to note how similar its behavioural manifestations are to drug addiction, and to then mistakenly conclude that because the processes are descriptively similar, they are functionally identical:

....interpersonal dependency is not like an addiction,
not something analogous to an addiction; it is an addiction
(Peele 1977 p13)

We noted above that the early medical model thought that addiction was a problem to do with drugs not people. These general theories represent an alternative misconception when they argue that addiction is a problem to do solely with people, not with drugs.
For example, Fuller et.al. (1987) entitled their work "On the irrelevance of substances in defining addictive disorders". They compared the self-reported levels of use for "22 potentially addictive substances to those for 18 non-substance consuming activities such as gambling and television watching" (from their abstract). The authors noted that levels of substance abuse were significantly correlated with levels of indirectly reinforcing activities (food, sex, love, television watching). And they concluded that because individuals exhibited similar levels of addiction to drugs, and pleasurable activities - in other words, because their frequency of non-substance consuming behaviour was descriptively similar to their frequency of substance abuse, these pleasurable activities must be addiction as much as substance abuse is addiction.
This focus on description serves a useful purpose for the helping professions. It allows them to identify addiction prone individuals, and attempt interventions with this knowledge (Jacobs 1987). Further, it is often impossible to move beyond description of these behaviours because the methods do not yet exist to gather empirical data which explains them accurately. Here I am thinking of the difficulty of establishing, for example, the neurological antecedents to a person's development of a love of gardening, or a dependent love style.
However practical worth does not equate with conceptual strength. The general theories have limited conceptual strength because they are descriptive, or if they attempt to explain addiction, they do so at a Psychological level, invoking explanations of "Psychological dependency" as noted above. There are some exceptions to this rule. Jacobs' two factor theory of addiction proposes that addicted individuals are either chronically hyper or hypo-aroused. This abnormal arousal is hypothesised to be a contributing factor to addiction. While this idea is a step in the right direction for general theories, because it is moving toward a physiological explanation, Jacobs' second factor clearly contradicts one of the major assumptions of the pharmacological theory. Jacobs writes:

The second precondition that must exist before the stage is fully set for acquiring an addictive pattern of behaviour is a childhood and adolescence marked by deep feelings of inadequacy, inferiority, and a pervasive sense of rejection by parents and significant others. Such feelings would be expected to stimulate behaviours and activities that would produce relief from this psychological distress. (p 44)

In other words, addicts develop a psychological dependency on drugs, or addictive substances to achieve positive affect, which can reduce the stress induced by their childhood and adolescent experience. Or more simply, the thing which maintains addictive behaviour is the fact that the addictive behaviour causes positive affect. This idea directly contradicts recent research in addiction which suggests that because many long term addicts report that they no longer enjoy the drug experience, but still crave drugs more and more, positive affect produced by drugs cannot be what maintains drug ingestion (Robinson and Berridge 1993).
Really what we are observing when we note these differences between the pharmacological model, and the general model of addiction, is that they are describing two different processes that appear similar. Psychological dependence should not be considered addiction, because there is no evidence which can explain how it is functionally similar to substance abuse.

The line between addiction and dependency

How can we "draw the line" between addiction and psychological dependency? I would argue that any behaviour which can be demonstrated to directly affect brain reward pathways, should be considered addiction, while those for which there is no comparable evidence, but which manifest similar behavioural symptoms, should be incorporated into a new model of "Psychological dependence". When I speak of a substance "directly" affecting a brain reward pathway, I am referring to the manner in which it changes receptor structure and function, that I outlined above. Substances which directly affect the brain must necessarily be able to cross the blood brain barrier, rather than relying upon sensory neurons to produce their effects.
The general theories of addiction have attempted to view as "addictive" a wide range of activities too numerous to mention here. However these activities share basic similarities in that they are assumed to activate brain reward pathways indirectly. I consider gambling as an example because it is representative of a number of these activities in that it can have large costs on personal, family, financial and social functioning (Dickerson 1984) and can lead to loss of control when undertaken at high frequencies. First we may ask "Why has gambling sometimes been considered an addiction?"
Some have considered gambling to be an addiction because there are behavioural similarities between gambling and substance use that is out of control. Cummings et al. (in Dickerson 1984 p59) reported that about half of all gambling relapses they studied were associated with what they called "negative emotional states". Given Koob's assumption above about the links between the DA system, and the ventral striatum, which converts emotion into motivated action, the pharmacological model has argued that addict relapse can be precipitated by negative emotional states working through this brain site. This similarity has prompted comparisons between gambling and substance abuse.
Although as I have already noted, gambling cannot directly affect brain reward mechanisms, "in so far as an activity causes pleasure, we may assume it does so by activating the same neural system as addictive drugs. Thus it is conceivable that continued involvement with a pleasurable activity may release sufficient amounts of dopamine for the activity to be a powerful reinforcer." (Walker 1992 p 181) Given this type of reasoning it is easy to see why repetitive gambling behaviour has been mistaken for addiction.
There are however three reasons for rejecting the idea that gambling and any other substance/activity which indirectly stimulates brain reward pathways are addictions. Firstly the conception or assumption that their reinforcing properties are produced by DA release is not the same thing as evidence that this is what produces their reinforcing properties- the latter is currently lacking.
Secondly, it has been hard to demonstrate withdrawal effects upon cessation of activities which indirectly stimulate reward pathways, and this makes it harder to argue that they produce neuroadaption, which the pharmacological model sees as a common condition produced by drug addiction. Custer (1982 in Dickerson 1984) present one of the few exceptions to this. He reported that if gamblers had just stopped betting prior to hospital admission, it was not uncommon for staff to observe withdrawal symptoms similar to opiate withdrawal. He suggested however that these could have been due to sleep starvation. Wray and Dickerson (1981 in Dickerson 1984) also document withdrawal symptoms in gamblers. However their study was based on self-reports from gamblers attending Gamblers' Anonymous, who presumably recounted to each other at the start of each meeting how bad they had felt while gambling, and when they couldn't afford to gamble. Further the study was retrospective, which calls into question the reliability of the gamblers' memories. There are of course some addictive drugs which produce minimal withdrawal symptoms (such as "crack" cocaine). I should not be mistaken for asserting that withdrawal symptoms are a necessary condition of addiction.
Thirdly, we may note that when Walker writes : "in so far as an activity causes pleasure, we may assume it does so by activating the same neural system as addictive drugs" what he is implying is that these activities are repeated by the individual because they produce positive affect. Walker (1988) notes that gambling is probably not maintained by positive affect, but rather feelings of control and self worth. These are created because the gambler (mistakenly) believes that he/she has won at a game of skill, and not chance. However in discussing the theory of psychological dependence above, I noted that although it is commonly positive affect produced by the activity which maintains dependence, "the fulfilment of a psychological need" will also serve this purpose. And the need to experience feelings of self worth fits this criteria. However I have already noted above that this type of process is best considered psychological dependence rather than addiction.
One point which bears further consideration is whether or not psychological dependence has a physiological basis. In my opinion it is wrong to speak of the psychological as if it were distinct from the physiological, as some authors do. Rather, what I am trying to argue is that the specific physiological mechanisms that lead to psychological dependence differ from those that lead to addiction. Of course this does not mean that the two cannot occur together, or that psychological dependence cannot increase the strength of an addiction and vice-versa.
In summary, I believe that behaviours such as repeated running, exercising, sex, consumption of food, gambling, leisure activities such as gardening, and love represent a functionally different process to addiction to substances. Simply labelling people who lose control over the amount of time and resources that they spend at these activities as addicts, and their behaviour as "addiction" both fails to help them, and creates confusion in the attempt to better understand these processes.

REFERENCES

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