Tuesday, September 13, 2011

addiction is not a disease of the brain?

NPR | Addiction has been moralized, medicalized, politicized, and criminalized. And, of course, many of us are addicts, have been addicts or have been close to addicts. Addiction runs very hot as a theme.

Part of what makes addiction so compelling is that it forms a kind of conceptual/political crossroads for thinking about human nature. After all, to make sense of addiction we need to make sense of what it is to be an agent who acts, with values, in the face of consequences, under pressure, with compulsion, out of need and desire. One needs a whole philosophy to understand addiction.

Today I want to respond to readers who were outraged by my willingness even to question whether addiction is a disease of the brain.

Let us first ask: what makes something — a substance or an activity — addictive? Is there a property shared by all the things to which we can get addicted?

Unlikely. Addictive substances such as alcohol, heroin and nicotine are chemically distinct. Moreover, activities such as gambling, eating, sex — activities that are widely believed to be addictive — have no ingredients.

And yet it is remarkable — as Gene Heyman notes in his excellent book on addiction — that there are only 20 or so distinct activities and substances that produce addiction. There must be something in virtue of which these things, and these things alone, give rise to the distinctive pattern of use and abuse in the face of the medical, personal and legal perils that we know can stem from addiction.

What do gambling, sex, heroin and cocaine — and the other things that can addict us — have in common?

One strategy is to look not to the substances and activities themselves, but to the effects that they produce in addicts. And here neuroscience has delivered important insights.

If you feed an electrical wire through a rat's skull and onto to a short dopamine release circuit that connects the VTA (ventral tegmental area) and the nucleus accumbens, and if you attach that wire to a lever-press, the rat will self-stimulate — press the lever to produce the increase in dopamine — and it will do so basically foreover, forgoing food, sex, water and exercise. Addiction, it would seem, is produced by direct action on the brain!

(See here for a useful Wikipedia review of this literature.)

And indeed, there is now a substantial body of evidence supporting the claim that all drugs or activities of abuse (as we can call them), have precisely this kind of effect on this dopamine neurochemical circuit.

When the American Society of Addiction Medicine recently declared addiction to be a brain disease their conclusion was based on findings like this. Addiction is an effect brought about in a neurochemical circuit in the brain. If true, this is important, for it means that if you want to treat addiction, you need to find ways to act on this neural substrate.