Addiction as a Brain Disease

News Blog readers know that the CLAHRC WM Director is a completely unapologetic advocate of Enlightenment values. Sciences does not just provide information about nature. It also changes our world view of nature. Since we humans are part of nature, it has the potential to change how we think about ourselves. A natural, but untutored, view of addiction is that it is a moral failure – a lack of personal responsibility leading to voluntary indulgence in hedonistic pursuits. However, addiction is a neuro-physiological condition with an organic basis – just like other psychological phenomena.[1] The clue was always there – the condition affects some people but not others, and applies to behaviours such as video-gaming, not just toxic substances. Activation of specific neurobiological circuits is associated with:

1. Intoxication
2. Withdrawal
3. Craving.

Intoxication leads to a learned response so that, over time, dopamine cells start firing, not in association with the reward, but in anticipation of it – the classical mechanism in learning. The CLAHRC WM Director does not think of alcohol until dinner-time. The dinner is activating his dopaminergic neurons and creating craving. Fortunately, they stop firing when he has a glass of wine so he can stop drinking (most days). But a person predisposed to addiction would not experience satiation. Worse, dopaminergic responses to the stimulus attenuate over time so that more of the agent is required to produce the same gain. Worse still, dopaminergic responses to other (non-addictive) positive stimuli – say from getting a paper published in a high-ranking journal – are also attenuated. So the addicted person enters a downward spiral. Compensatory down-regulation of dopamine signalling elsewhere in the brain leads to dysphoria (depression) and a drop in motivation. An afflicted person’s life thus descends into further chaos.
Why are some people more susceptible than others? Here are risks:

1. Genetic predisposition; a number of specific genetic polymorphisms predisposing to addiction have been found.
2. Early exposure – the adolescent years especially, as this is a time of high neuroplasticity.
3. Poor familial and social support.
4. Restricted alternatives – sport should be encouraged.

This deeper knowledge of the molecular and neuro-anatomical basis of addiction is leading, not just to new pharmacological and neuro-biological treatments, but a profound change in social attitudes. This is manifest in, for example, more lenient sentencing for non-violent offences perpetrated by people with addictions. Science is a civilising process that does not just inform how to reach an objective, but also colours our choice of objectives.

— Richard Lilford, CLAHRC WM Director

Reference:

1. Volkow ND, Koob GF, McLellan T. Neurobiologic Advances from the Brain Disease Model of Addiction. New Engl J Med. 2016; 374: 363-71.