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What is addiction? 

What is addiction?
What is addiction?
Addiction (Oxford Psychiatry Library)

Professor David J. Nutt

and Dr Liam J. Nestor


Key points

  • Addiction is a brain disease.

  • Addiction is a chronic relapsing disorder.

  • Addiction involves the chronic pharmacological actions of substances in the brain.

  • There are different types of addiction (e.g. alcohol, cocaine).

  • Individuals may be more vulnerable to addiction than others.

  • Endophenotypes of addiction may facilitate diagnosis and treatment.

  • Addiction may involve numerous factors (e.g. social, biological).

  • Addiction does not happen immediately.

  • There are stages of addiction (e.g. preoccupation, loss of control).

  • There are also ‘non-substance’ behavioural addictions (e.g. gambling).

  • Limited use of addictive drugs is clinically distinct from addiction.

From the Latin word addictio (enslaved), ‘addiction’ is a concept that has been subject to much debate for some considerable time. At its origin, ‘addiction’ simply referred to ‘giving over’, being ‘highly devoted’, or engaging in behaviour habitually, with positive or negative implications. Subsequent and more modern views of addiction to substances were framed around observations that those afflicted experienced strong, overpowering urges, which were conceived to be more disease-like in their origins.

Substance addiction is now defined as a chronic relapsing disorder characterized by: (1) compulsion to seek and take the substance, (2) loss of control in limiting substance intake, and (3) the emergence of a negative emotional state (e.g. dysphoria, anxiety, irritability) reflecting a motivational withdrawal syndrome when access to the substance is prevented (defined as substance dependence by the Diagnostic and Statistical Manual of Mental Disorders (DSM) of the American Psychiatric Association). According to DSM, there are seven main criteria for substance dependence (see Box 1.1).

Importantly, the occasional, but limited, use of addictive substances is clinically distinct from escalated substance use, loss of control over substance intake, and the emergence of chronic compulsive substance-seeking that characterizes addiction.

From modern-day psychological and pharmacological perspectives, substance addiction (including alcohol) may be seen as a manifestation of the long-term pharmacological actions of these substances on the receptor mechanisms of the brain. Evidence, however, is beginning to emerge that non-substance (i.e. behavioural addictions, such as pathological gambling) show strong behavioural and neural similarities to substance addiction (see Box 1.2).

It is also surmised that some individuals may be more susceptible to substance addiction. This susceptibility may be due to abnormal receptor mechanisms in the brain which have been genetically inherited (i.e. a neurobiological predisposition). Substances of addiction exacerbate this predisposition. The development and emergence of substance addiction, however, may involve many factors—biological (i.e. genetics), social (e.g. socio-economic background), method of administration (e.g. intravenous, oral). Furthermore, these factors are unlikely to be independent, instead interacting with one another at different points in the addiction trajectory.

The emergence of endophenotypes may also be of relevance to the development and treatment of addiction disorders. The endophenotype may be neurophysiological, cognitive, or neuropsychological. Endophenotypes are present before addiction onset and in individuals with heritable risk for addiction (e.g. unaffected family members). They can be used to facilitate diagnosis and in the search for causative genes in addiction disorders.

1.1 Stages of addiction

Addiction does not develop immediately. Rather, its development should be thought of as a process made up of several stages that are comprised of elements (see Figure 1.1). Upon the initialization of substance use, the individual may pursue some course of action for appetitive effects or motives (e.g. pain reduction, affect enhancement, arousal manipulation). There has been a clustering of different addictive behaviours, involving hedonistic (e.g. drug use, sex, gambling) or nurturant (e.g. shopping addiction, love, exercise) motives. Other or additional motives may be plausible, however (e.g. to achieve fantasy or oblivion). All addictions may have in common the capacity to alter the subjective experience of the self.

Figure 1.1 Stages of addiction. Illustration of the proposed stages of addiction and their elements.

Figure 1.1
Stages of addiction. Illustration of the proposed stages of addiction and their elements.

Addiction unfolds for some individuals but not others. This may be a reflection of individual differences prior to engaging in substance use. Many self-described addicts, for example, have reported feeling ‘different’ from others prior to developing an addiction. These differences have been described to include feeling relatively uncomfortable, lonely, restless, or incomplete. Once a behaviour is tried (e.g. drinking alcohol) that decreases or eliminates the reference point of discomfort, a process of addiction may unfold. This explains why pre-existing psychopathologies (e.g. anxiety, depression) may be a trigger for the emergence of substance use in some individuals. This pre-existing vulnerability may also be genetic in origin, accounting for up to 50% of the variance of addiction.

Many people, however, do not report feeling different prior to developing an addiction. Instead, these individuals may engage in substance use, as it is perceived as highly valued or enjoyable. This inflated evaluation may possibly come from the rapid effects that occur from substance use and which the person desires to repeat. The initial reaction to substance use may be experienced as extremely positive, making it particularly appealing. This is not to say, however, that in these individuals, there is no pre-existing propensity (e.g. trait impulsivity, sensation-seeking) that influences them to engage in substance use.

The preoccupation with substance use may begin to develop following the initial appetitive effects. This second aspect of addiction involves excessive thoughts about the substance and excessive time spent planning to use the substance. Here, behaviour related to substance use ‘spills over’ into several aspects of a person’s daily life. Less time is spent on other activities despite the potentially diminishing appetitive effects of the substance.

Tolerance and withdrawal are physiological hallmarks of addiction that contribute to preoccupation. Tolerance is seen as a need to engage in substance use at a relatively greater level in order to achieve the same desired effects. As tolerance increases, the person needs more alcohol or other drugs. This will lead to spending more time locating and engaging in substance use. This indicates an increasing preoccupation.

Withdrawal refers to physiological or acquired discomfort experienced upon the abrupt termination of the substance. If withdrawal symptoms exist and worsen, a person is likely to spend greater amounts of time recovering from after-effects (e.g. hangovers). Thus, the processes of tolerance and withdrawal will mean the person spends more time locating, engaging, and recovering from substance use. For many addicts, the initial period of substance use is driven by pleasure. Over time, the motivation to use switches to a desire to minimize withdrawal.

Also possibly related to tolerance or withdrawal is craving. Craving (i.e. urges) to engage in substance use has become a defining feature of addiction. Craving is not the same thing as physiological withdrawal. Instead, it involves an intense urge to engage in a specific act and may be experienced long after the dissipation of withdrawal. Craving is often a precipitator of relapse and is now a target for the development of relapse prevention medications. Craving has also been proposed as a diagnostic feature of the addictions to be added to the DSM-V.

Temporary satiation, experienced during acute engagement in the addictive behaviour, is also experienced during the process of addiction. This has been described by addicts as a sense of distraction from life’s problems. Here, acute substance use becomes increasingly more incentivized (i.e. gains greater incentive value). Non-addictive alternatives may lose incentive value over time despite the discomfort in trying to achieve satiation. There are instances, however, in which the person suffering from addiction reports no longer being able to achieve satiation from substance use, presumably due to excessive tolerance.

Drug addiction is characterized by continued use and recurrent relapse despite serious negative consequences. Addicts often report feeling compelled towards substance use while sensing incomplete control over their behaviour. This appears to implicate decrements in higher order cognitive functioning, akin to a loss of control.

Impulsiveness has been suggested to indicate an addiction-related loss of control. This may involve spontaneous urges to engage in substance use. Loss of control may further suggest a struggle between implicit (unconscious) and declarative (conscious) systems. The implicit system may facilitate impulsive behaviour associated with addiction related events, which are strongly embedded in memory. The declarative system, in turn, may fail to inhibit automatic (i.e. unconscious) substance use in response to craving.

This suggests that a loss of control during addiction involves competing neural signals between primitive, reflexive brain regions that kindle impulsivity and higher brain areas that involve cognitive processing (e.g. behavioural inhibition). Indeed, research is beginning to elucidate why a loss of cognitive control may be a central component for both the initiation of, and continued, substance abuse (see Chapter 4).

Negative consequences (e.g. physical discomfort, social disapproval, financial loss, or decreased self-esteem) will begin to take hold following chronic substance use. Indeed, continuing to engage in the addictive behaviour, despite suffering numerous negative consequences, is a criterion for dependence. There may also be a fear of having to cope with the perceived day-to-day stresses of life upon substance use cessation. This may be due to an accumulation of addiction-related consequences (e.g. debts) or having to endure raw emotional experiences without concurrent self-medication.

The failure to learn to cope without substance use and suffering withdrawal-related phenomena may additionally add to this element of negativity. Negative consequences may vary across contexts. However, role consequences (e.g. difficulty fulfilling one’s role as parent, spouse, or co-worker) are usual aspects of this negativity. Importantly, such negative consequences may bring negative reinforcement. Here, substance-dependent individuals are likely to further engage in substance use in order to eliminate or reduce the physical and psychological discomfort experienced as a result of chronic addiction behaviour.

References and Further Reading

American Psychiatric Association (2000). Diagnostic and statistical manual of mental disorders. Vol. 4. American Psychiatric Press, Washington DC.Find this resource:

    Dalley JW, Fryer TD, Brichard L, et al. (2007). Nucleus accumbens D2/3 receptors predict trait impulsivity and cocaine reinforcement. Science, 315, 1267–70.Find this resource:

      Ersche KD, Turton AJ, Pradhan S, Bullmore ET and Robbins TW (2010). Drug addiction endophenotypes: impulsive versus sensation-seeking personality traits. Biological Psychiatry, 68, 770–3.Find this resource:

        Goodman A (1990). Addiction: definition and implications. British Journal of Addiction, 85, 1403–8.Find this resource:

          Meyer RE (1996). The disease called addiction: emerging evidence in a 200-year debate. Lancet, 347, 162–6.Find this resource:

            Gould RW, Duke AN and Nader MA (2013). PET studies in non-human primate models of cocaine abuse: translational research related to vulnerability and neuroadaptations. Neuropharmacology, pii, S0028–3908(13)00046–4.Find this resource:

              Sussman S and Sussman AN (2011). Considering the definition of addiction. International Journal of Environmental Research and Public Health, 8, 4025–38.Find this resource:

                World Health Organization (1992). The ICD-10 classification of mental and behavioural disorders: clinical descriptions and diagnostic guidelines. World Health Organization, Geneva.Find this resource:

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