Hulton Archive/Getty Images
Hulton Archive/Getty Images
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.
All the rest — the actual gambling or drug taking, the highs and lows, the stealing, lying and covering up, the indifference to work and incompetence in the workplace, the self-loathing and anxiety about getting high, or getting discovered, or about trying to stop, and the loss of friends and family, the life stories and personal and social pressures — all these are merely symptoms of the underlying neurological disease.
But not so fast. Consider:
All addictive drugs and activities elevate the dopamine release system. Such activation, we may say, is a necessary condition of addiction. But it is very doubtful that it is sufficient. Neuroscientists refer to the system in question as the "reward-reinforcement pathway" precisely because all rewarding activities, including nonaddictive ones like reading the comics on sunday morning or fixing the leaky pipe in the basement, modulate its activity. Elevated activity in the reward-reinforcement pathway is a normal concomitant of healthy, nonaddictive, engaged life.
Neuroscientists like to say that addictive drugs and activities, but not the nonaddictive ones, "highjack" the reward-reinforcement pathway, they don't merely activate it. This is the real upshot of the rat example. The rat preferred lever-pressing to everything; it dis-valued everything in comparison with lever-pressing. And not because of the intrinsic value of lever-pressing, but because of the link artificially established between the lever-pressing and the dopamine release.
If this is right, then we haven't discovered, in the reward reinforcement system, a neurochemical signature of addiction. We haven't discovered the place where addiction happens in the brain. After all, the so-called highjacking of the reward system is not itself a neurochemical process; it is a process whereby neurochemical events get entrained within in a larger pattern of action and decision making.
Is addiction a disease of the brain? That's a bit like saying that eating is a phenomenon of the stomach. The stomach is an important part of the story. But don't forget the mouth, the intestines, the blood, and don't forget the hunger, and also the whole socially-sustained practice of producing, shopping for and cooking food.
And so with addiction. The neural events in VTA clearly belong to the underlying mechanisms of addiction. They are necessary, but not sufficient; they are only part of the story.
Remember: normally there is a dynamic quality to our actions and preferences, just as there is with those of rats. We enjoy exercising, but we soon get tired or bored. But rest, too, soon loses its appeal. We eat, and then we are sated. And then we are ready for the tread mill again. And so on. Things have gradually changing and complementary values. In addiction, this dynamic goes rigid. The addicts goal assumes a fixed value, and the value of everything shrinks to zero, and with terrible costs.
Our strategy was to look for systematic effects that all and only the addictive drugs and activities have on addicts. And we've found what we were looking for. The effects are behavioral and experiential. The things that addict us all produce a very distinctive breakdown in the organization of our preferences, actions and choices.
Is addiction a disease of the brain? This strikes me as a dubious falsification of what is, really, a phenomenon that can only be understood in terms of the life, choices, needs and understanding of the whole person.
Next week: an extended discussion of Gene Heyman's Addiction: A Disorder of Choice.
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