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What is addiction?

Ask a politician what addiction is and you will likely have a response that includes the term “self-inflicted problem”. Ask a member of the general community what addiction is and you may hear remarks about people taking drugs for the sake of it. Ask a health professional about addiction and you are likely to have a variety of responses. You may be greeted with “Oh I don’t deal with those sort of problems”. You may receive an elegant discourse on social learning theory or a sociological explanation on power relations in society, or it may be explained that substance use is a consequence of a mental health disorder.

Confused? You might well be.

Historically there has been immense confusion as to what addictive disorders are, with many conflicting views, proposed explanations, and philosophies. One should not criticise members of the community, various health professionals or even politicians for these immensely varied interpretations. In reality, the nature of addiction has been explored from many different professional and scientific standpoints, and there is a lot of truth in explanations that come from social learning theory, social science, psychiatry, and epidemiology. However, what has been lacking is a coherent synthesis of what we know about these disorders and that people with the disorders experience.

What, therefore, is this thing called “Addiction”?

At one level addiction is simple to understand. It starts, necessarily, with the repeated use of a substance which has particular effects on the brain and mind. Some of the substances are naturally occurring or, like alcohol, are produced through natural processes such as fermentation of grapes or cereals. Some are pharmaceutical substances or otherwise chemically manufactured. A more modern form of addiction is that due to a repetitive activity such as gambling or gaming, but this article will focus on addictions due to substances.  Historically there has been immense confusion as to what addictive disorders are…

Substance use is rarely, at first, a solitary activity. In all human societies, alcohol consumption (for example) is most likely to occur in a group setting, particularly amongst friends and peers. There are, therefore, important social and cultural influences on the uptake of a particular substance – be it alcohol, tobacco, marijuana, Ecstasy tablets, coca leaf or betel nut.

The field of behavioural psychology has contributed a lot to our understanding of how repetitive patterns of substance use can develop. In particular, people learn the effects of the substance in certain settings and the perceived advantages and disadvantages. The most widely accepted theory is social learning theory which states that a repetitive behaviour such as drinking occurs through the person observing or experiencing a behaviour and its positives and negatives, that it is a cognitive process, and that it is influenced by the personal and social environment. Positive observations and experiences are likely to encourage consumption, negative and adverse ones will likely discourage further use or use beyond certain limits.

But there is more…

These explanations contribute to our understanding of how repetitive substance use can start and become a pattern or habit. However, addiction is so much more than this. In addiction, the use of a particular substance increasingly occupies centre stage in that person’s life. It continues even despite harmful consequences, whereas sociological and behavioural psychology explanations would suggest that substance use would be sensitive to harmful consequences and would be reined-in at that point.

With addiction, this does not happen.

One of the central features of what is termed substance dependence (essentially synonymous with addiction) in the International Classification of Diseases, 10th Revision (ICD 10), is “continued use despite harmful consequences”. How can loss of control over substance use or the presence of withdrawal symptoms have explanations in social science or psychological ways?

People with addictive disorders increasingly experience feelings about alcohol or drugs that seem beyond these explanations. The sense of increasing loss of control, the sense that life is moving in a direction that they seem to have little influence over, the disturbing experiences due to using too much or the after-effects such as the emergence of withdrawal symptoms suggest that something far more powerful is developing inside them.

Research largely undertaken over the past 20 years has identified key circuits in the brain that are responsible for the increasingly powerful grip addiction has on an individual, and the transition from substance use which is largely under a person’s control to the stage where it clearly is not. The neurocircuits that are the anatomical location of addiction are located in the basal ganglia, the ventral tegmental area of the mid-brain and the lower forebrain. There are four key neurocircuits which in response to repeated use of a substance become physiologically altered or “re-set” in an enduring way. These include:

1. The reward circuitry

The reward circuitry becomes progressively “hijacked” by use of that substance, with the result that other enjoyments (food, love, sport, sex) become blunted and dull.

2. The alertness system

Many substances suppress alertness (alcohol for example) and repetitive substance use will cause adaptive changes in these pathways resulting in a heightened state of arousal or excitation. This helps explain the common feelings of hyper-arousal and anxiety that occur in persons with addiction. It provides a ready explanation as to how people with addictive disorders are triggered by the site, smell or taste of their preferred substance and can be triggered also by environments associated with alcohol consumption (for example) or groups of friends or environments such as a pub or club, or even unpleasant internal feelings.

3. Prioritisation

As addiction develops, priorities change and can do so fundamentally. Changes in the salience  neurocircuitry result in substance use and activities associated with it being accorded a much greater priority by the individual. Activities that once had high priority become relegated to the periphery.

4. Behavioural control

With the development of addiction, there is progressive impairment of these behavioural control pathways such that primitive responses described above which produce urges and loss of control over substance use, have no brake put on them. Substance use therefore tends to continue until no more is left or the person becomes stuporous or is told by a partner or elder to stop.

Neurobiological changes explain how addictive disorders develop from patterns and habits of use to powerful internal drives that become less and less responsive to attempts at voluntary control. There is a sense of substance use escaping the ability of the person to regulate it. Instead, it reflects an unthinking primitive neurobiological drive.

From this recently acquired scientific knowledge, we can now interpret addictions as the serious disorders they are. Modern scientific understanding is increasingly in accord with what those with addictive disorders actually experience. It is curious that it has taken a hundred years of scientific endeavour to bring professional views more in alignment with those of people who have actually experienced addiction for themselves and know powerful and destructive a disorder it can be.

As an important mentor in my professional life, Professor Griffith Edwards, said to me, “Never underestimate addiction”.

About Professor John Saunders: He was the co-chair of the Substance Use Disorders Research Working Group for DSM-5 from 2003 to 2008, though was not closely involved with the subsequent development of the DSM-5 diagnostic criteria. He is a current member of the Substance Use Disorders Working Group of the World Health Organization, which is developing the diagnostic concepts and guidelines for the forthcoming 11th Revision of the ICD (ICD 11).