Addiction is described in the DSM-IV-TR under the label Substance Abuse Disorder as a condition that includes dependence on and abuse of a drug. It notes that the drug is usually taken voluntarily for the effect on the central nervous system or to prevent withdrawal symptoms.

Dependence is described as using the drug despite negative consequences along with the presence of certain other clinical signs. Two of these that are related to our discussion are tolerance and withdrawal.

There are three different types of tolerance:
1) Metabolic tolerance wherein the body creates more enzymes in order to be able to break down the drug quicker
2) Cellular tolerance refers to the brain adjusting itself so that the effects of the drug are minimized
3) Learned tolerance in which people learn behaviours that compensate for and mask their intoxication.

The effect of all three forms of tolerance is to require a larger dose of drugs to be used in order to produce the (desired) effect.

Dependence is related to withdrawal. In this situation a person needs to use drugs in order to feel normal. If he/she fails to use drugs then the withdrawal symptoms may occur. The dependence hypothesis suggests that addicts use drugs in order to avoid withdrawal symptoms. It should be explicitly noted that not all withdrawal symptoms are physical. The fact that many addicts relapse after months of continued abstinence suggests that the dependence hypothesis does not fully explain addictive behaviour.

The hedonic hypothesis suggests that addicts use drugs in order to feel pleasure. Although the literature of Narcotics Anonymous cannot be described as an academic source it has been “peer reviewed” by millions of addicts and found to be a generally acceptable description of the experience of addiction as viewed from the inside. In a qualitative sense this is a rich text and worth citing. This literature says that “We used [drugs] to live, and lived to use [drugs]”. The reported experience of millions of addicts does not include pleasure. And indeed, if using drugs was pleasurable why are we recovering addicts so motivated to stop using? The truth is that obsessive and compulsive drug use is not pleasurable and at best the “high” is a temporary distraction from the psychosocial problems that using drugs creates.

The incentive-sensitization theory suggests that addiction is a learned response in the manner of behavioural association. By initially gaining pleasure from a drug the user is reinforced to use it again. By continually using it the user associates pleasure with the drug. The mental representations of using the drug become rewards in themselves and so behaviour that is likely to result in using the drug becomes attractive regardless of the consequences.

This is related to the wanting-and-liking theory. Wanting is seen as the craving for the drug. Liking is described as the pleasure associated with using the drug. Wanting is thought to be related to the reward systems of the mesolimbic subsystem of the dopaminergic neurotransmitter system. This system projects to the limbic system and the frontal cortex.Craving could then be modeled as an associative process that occurs subconsciously between drug taking and the different cues related to it.

However, learned associations can also be “unlearned”. Many addicts indicate that using drugs was no longer pleasurable. Wouldn’t one expect the wanting-and-liking theory to stop applying once the consequences of addiction start racking up for the addict?

I relate cravings after long periods of abstinance to learned associations where drugs became a maladaptive “coping mechanism” (by using drugs the addict escaped difficult emotions and situations). I would suggest this to occur especially when encountering novel stressful situations.

There is evidence to suggest genetic vulnerability to drug abuse, but no specific gene has been isolated. The literature of Narcotics Anonymous has a pervasive theme that they call the “hole in the soul”. Many of the stories in the literature focus on social isolation and feelings of unworthiness as reasons that addicts “fell in love” with their substance. If I were to suggest a risk factor for addiction it would be a sense of not belonging.

Drug abuse has a negative effect on the neurotransmitter systems. For example: MDMA (“ecstasy”) and LSD (“acid”) are both toxic to serotonergic neurotransmitters (Banich, 2004, p 55). Chronic alcohol use is associated with damage to the thalamus and limbic system and produces memory deficits.

There are also other dangers associated with behaviours related to drug addiction. Poor diet can lead to nutritional deficiencies. Excessive risk-taking behaviour (such as driving drunk or high) can also be related to the effects of drugs. Street drugs are often “cut” (contaminated) with other substances such as strychnine which creates health risks.

I personally do not believe that addiction is purely a chemical process. As an example: I found an interesting article by Johnson et al (2007) about Topamirate (which is branded as Topamax in South Africa). Apparently it blocks the mesolimbic dopamine systems to reduce the reward felt while drinking alcohol. The optimism from the study results seems to be based on a harm reduction treatment paradigm but I thought it was still an interesting result. However, one might assume that the study was conducted with motivated clients (it does not say this in its parameters), in which case are the results really that good when compared to current interventions?

Addiction is seldom unaccompanied by behavioural disturbances. Most drugs of abuse are illegal. Thus to be an addict for many is to become a criminal. Addicts deal with cognitive dissonance around this (and many other issues) through various defense mechanisms such as denial. Addiction is also often accompanied by emotional disturbances and developmental issues.

In the light of these observations I believe that addiction is a complex psychosocial behaviour and while it may have roots in neurochemical processes I maintain that adjunctive psychotherapy will always be necessary even if a drug is found to effectively treat the organicity of the disease.

References:

Banich, MT. (2004) Cognitive Neuroscience and Neuropsychology (2nd ed.). Boston: Houghton Mifflin Company.

Johnson et al. (2007). Topiramate for Treating Alcohol Dependence: A Randomized Controlled Trial [Electronic version], JAMA, 298, pp 1641-1651.