Drug addiction as a compulsive disorder
Addiction is something that I feel very strongly about. Having worked as a preclinical researcher with one of the most exciting drug addiction research groups in the world, I have been exposed to many theories and models of this compulsive disorder, and I would like to use this forum to discuss some of them.
Let's start with an overview of the addiction process:
Let's start with an overview of the addiction process:
So, who are these vulnerable individuals?
Not everyone who takes drugs becomes addicted. In fact, it has been estimated that only between 15-25% of people who try drugs will eventually develop a substance abuse disorder (depending on the drug), and these people have to work really hard in order for that to happen - by that I mean that a lot of drug has to be consumed, over a long period of time (although it is true that the initial reaction to a drug can facilitate this - for example, someone with high anxiety trying alcohol for the first time before a stressful situation can feel an immediate sensation of relief, and a sense of 'this is what I've been missing all these years'). But what is it about these individuals that makes them different? This is a huge research topic that is being investigated by different groups all over the world, including my former lab.
In the 1960s and '70s, EJ Khantzian was one of the first researchers to investigate the issue of individual vulnerability. Prior to this, drug addiction was a stigma; seen to be the fault of the individual, and thought simply to represent a willful lack of self-discipline. Khantzian, a clinical psychologist, interviewed drug addicts and found a correlation between drug abuse and the incidence of affective or psychological deficits in these individuals. These observations helped to formulate the Self-Medication Hypothesis, which holds that drug abuse is an attempt to 'correct' personality or behavioural problems such as low self-esteem or anxiety. In addition, the type of drug abused is self-selected, with specific deficits requiring the administration of a particular pharmacological agent. For example, according to Khantzian, opiate abusers are introspective and use opiates to facilitate a withdrawal from the outside world via their emotional anaesthetic properties. Conversely, stimulant abusers use cocaine or amphetamine to facilitate interaction with the external world, and to bolster artificially high levels of self-esteem and confidence.
While I applaud Khantzian, and am a great admirer of his work, I'm not so sure that this is the full picture. Firstly, self-medication is generally a GOOD thing - people do it because they feel better afterwards. I agree that initial drug use, and in some cases drug abuse, can be explained by the self-medication hypothesis. However, full-on addiction is a stage further than this, and instead constitutes a compulsive disorder, whereby the individual has limited control over what he or she is doing. The accepted consensus now is that there are two sets of vulnerability factors: those that predispose to trying a drug and continuing to use it because it feels good, and those that predispose to developing compulsive drug-taking, despite aversive consequences. Importantly, both sets of factors must be in place for addiction to take place. In addition, socioeconomic factors play a huge role, including the environment the individual lives in, whether there is a strong familial support network, and the peer group that the individual chooses to interact with.
In effect, there are three components that must align for a person to become addicted to drugs:
1. The biological predisposition must be present;
2. Consumption of the drug must occur;
3. The environmental setting must encourage drug-taking behaviour.
[It is important to note at this point that clinical studies can be difficult to interpret, due to their retrospective nature. Consequently, it is essential to develop animal models and simulations of addiction in order to allow the investigation of the underlying neurobiology, and its manipulation. Such models are incredibly sophisticated psychological constructs that permit assessment of behavioural and other parameters prior to any drug exposure: a major caveat of clinical studies is that we don't know if observed effects preceded drug use or are a consequence; i.e., whether any differences are causal or correlative.]
In the 1960s and '70s, EJ Khantzian was one of the first researchers to investigate the issue of individual vulnerability. Prior to this, drug addiction was a stigma; seen to be the fault of the individual, and thought simply to represent a willful lack of self-discipline. Khantzian, a clinical psychologist, interviewed drug addicts and found a correlation between drug abuse and the incidence of affective or psychological deficits in these individuals. These observations helped to formulate the Self-Medication Hypothesis, which holds that drug abuse is an attempt to 'correct' personality or behavioural problems such as low self-esteem or anxiety. In addition, the type of drug abused is self-selected, with specific deficits requiring the administration of a particular pharmacological agent. For example, according to Khantzian, opiate abusers are introspective and use opiates to facilitate a withdrawal from the outside world via their emotional anaesthetic properties. Conversely, stimulant abusers use cocaine or amphetamine to facilitate interaction with the external world, and to bolster artificially high levels of self-esteem and confidence.
While I applaud Khantzian, and am a great admirer of his work, I'm not so sure that this is the full picture. Firstly, self-medication is generally a GOOD thing - people do it because they feel better afterwards. I agree that initial drug use, and in some cases drug abuse, can be explained by the self-medication hypothesis. However, full-on addiction is a stage further than this, and instead constitutes a compulsive disorder, whereby the individual has limited control over what he or she is doing. The accepted consensus now is that there are two sets of vulnerability factors: those that predispose to trying a drug and continuing to use it because it feels good, and those that predispose to developing compulsive drug-taking, despite aversive consequences. Importantly, both sets of factors must be in place for addiction to take place. In addition, socioeconomic factors play a huge role, including the environment the individual lives in, whether there is a strong familial support network, and the peer group that the individual chooses to interact with.
In effect, there are three components that must align for a person to become addicted to drugs:
1. The biological predisposition must be present;
2. Consumption of the drug must occur;
3. The environmental setting must encourage drug-taking behaviour.
[It is important to note at this point that clinical studies can be difficult to interpret, due to their retrospective nature. Consequently, it is essential to develop animal models and simulations of addiction in order to allow the investigation of the underlying neurobiology, and its manipulation. Such models are incredibly sophisticated psychological constructs that permit assessment of behavioural and other parameters prior to any drug exposure: a major caveat of clinical studies is that we don't know if observed effects preceded drug use or are a consequence; i.e., whether any differences are causal or correlative.]
Can we predict who will become addicted?
In a word, no. Although many have used personality theory constructs (for example, the Tridimensional Personality Questionnaire, developed by Cloninger in 1987) to 'predict' who is at risk, the results are not convincing. Risk factors for initiating drug use have certainly been identified, including high levels of sensation- or novelty-seeking, impulsivity, and anxiety. As I mentioned above, it is difficult to extrapolate from clinical studies, as exposure to drugs causes subtle alterations in the brain, so it is impossible to know for sure whether behavioural or brain imaging differences between addicts and control subjects are due to the drug itself or pre-existed its consumption. This is where animal models come into their own. In both my former lab, and others around the world, we have been able to show that certain behavioural traits (including those mentioned above) predict addiction-like behaviour, using such models. We have also been able to develop 'compulsivity' models, which simulate out-of-control drug-taking, and have found that - like humans - only a subset of animals develop such compulsivity.
The brain mechanisms underlying this are still being investigated, but it has been shown that specific parts of the brain mediate different kinds of behaviours associated with drug-seeking in rats. This is a relatively new research area, but supports, to some extent, the notion of the 'hijacked' brain. This theory holds that by inducing changes in the brain, the abused drug gradually exerts so much control over behaviour that the individual relinquishes free will, and can no longer control his/her own actions. Of course there are limitations to this theory, most notably the fact that some addicted individuals DO voluntarily stop taking drugs (and we will never be able to adequately model this in rats), but it fits quite nicely with the biological data that have been collated thus far.
The brain mechanisms underlying this are still being investigated, but it has been shown that specific parts of the brain mediate different kinds of behaviours associated with drug-seeking in rats. This is a relatively new research area, but supports, to some extent, the notion of the 'hijacked' brain. This theory holds that by inducing changes in the brain, the abused drug gradually exerts so much control over behaviour that the individual relinquishes free will, and can no longer control his/her own actions. Of course there are limitations to this theory, most notably the fact that some addicted individuals DO voluntarily stop taking drugs (and we will never be able to adequately model this in rats), but it fits quite nicely with the biological data that have been collated thus far.
In my opinion...
Although there is increasing evidence to suggest that addiction is a brain disorder, with an underlying organic basis (just like heart disease or diabetes), biological factors are just one set of determinants. From a holistic viewpoint, drug addiction is a symptom of an underlying problem, and unless solid support measures are put in place for vulnerable individuals, these problems will have alternative negative manifestations, even if abstinence is achieved. In this regard, the importance of socioeconomic and psychological factors cannot be stressed highly enough - the most basic requirement of any individual is to have a useful place in society, and to feel loved and secure. Addiction behaviour often stems from feelings of hopelessness, despair, loneliness, and low self-esteem. In addition to abstinence, it is therefore necessary to break this self-destructive cycle, and provide psychological support and counselling for addicts. It is important to remember that it is absolutely not the case that a biologically-vulnerable individual will inevitably become addicted to drugs, and we must be very careful to avoid such thinking. Obviously much work remains to be carried out in this controversial area, but I feel that we are finally beginning to appreciate the complexity of drug addiction, and to take a more comprehensive approach to its treatment, and more importantly, its prevention.
For a more detailed look at drug addiction theories, please go to this page: Theories of Drug Addiction.
For a more detailed look at drug addiction theories, please go to this page: Theories of Drug Addiction.