Addicted Brains

A neuroscientist examines life on drugs.

A Brain's-Eye View of Addiction as a "Disease"

Neuroscience provides a whole new perspective on the war of definitions.

I’ve generally felt critical of the “disease” label for addiction. But having read your many comments and looked up some recent literature, I can now give it its due.

Psychiatrists – because they are doctors – rely on categories to understand people’s problems. Every mental and emotional problem fits a medical label, from borderline personality disorder to autism to depression to addiction. These conditions are listed in the DSM (Diagnostic and Statistical Manual of Mental Disorders) and the ICD (International Classification of Diseases) for anyone to read.

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The idea that addiction is a type of disease or disorder has a lot of support. I won’t try to summarize all the terms and concepts used to define it, but Steven Hyman does a good job. His argument, which reflects the view of the medical community (e.g., NIMH, NIDA, the American Medical Association), is that addiction is a brain disease (also see the Huffington Post). It is a condition that changes the way the brain works, just like diabetes changes the way the pancreas works. Specifically, the dopamine system is altered so that only the substance of choice is capable of triggering dopamine release to the nucleus accumbens (ventral striatum), while other potential rewards do so less and less. The nucleus accumbens (NAC) is responsible for goal-directed behavior and for the motivation to pursue goals, as I’ve described in detail in my book.

Different theories view dopamine differently. For some, dopamine means pleasure. But I follow Berridge's theory and data, showing that dopamine means attraction, not pleasure. Berridge shows that cues related to the object of addiction become “sensitized,” so they greatly increase dopamine and therefore attraction…which turns to craving when the goal is not immediately available. But pretty much all the major theories agree that dopamine metabolism is seriously altered by addiction, and that’s why it counts as a disease. The brain is part of the body, after all.

What’s wrong with this definition? It’s pretty accurate. It accounts for the neurobiology of addiction better than other definitions. It explains the helplessness addicts feel: they are in the grip of a disease, and so they can’t get better by themselves. It explains the incredible persistence of addiction, its proneness to relapse; and why “choice” is not the answer (or even the question), because choice is governed by motivation, which is governed by dopamine, and your dopamine system is “diseased.”

So, do I buy it? Not really. I do think it can be helpful. It truly does help alleviate guilt, and blame, and it gets people on track to seek treatment. Moreover, addiction is indeed like a disease -- thus a potentially useful metaphor.

Then why don’t I buy it? Mainly because every experience that has some emotional content changes the NAC and its uptake of dopamine. Yet we wouldn’t want to call the excitement you get when you’re on your way to visit Paris, or your favourite aunt, a disease. Each rewarding experience builds its own network of synapses in and around the NAC, and that network sends a signal to the midbrain: I’m anticipating x, so send up some dopamine, right now! That’s true of Paris, Aunt Mary, and heroin. In fact, during and after each of those experiences, that network of synapses gets strengthened: so the “specialization” of dopamine uptake is further increased. London just doesn’t do it for you anymore. It’s got to be Paris. Sex or music…they don’t turn you on any more; but coke sure does.

Brain changes don't mean disease. Physical changes in the brain are its only way to learn, to remember, and to develop. But we wouldn’t want to call learning a disease.

So how well does the disease model fit the phenomenon of addiction? How do we know which urges, attractions, and desires are to be labeled “disease”, and which are to be considered aspects of normal brain functioning? There would have to be a line in the sand somewhere. But there just isn't one. To the poets, love is a disease: lots of dopamine, extreme specialization, loss of other interests, and a strong tendency to recur.

Addiction doesn’t fit a specific physiological category. So, rather than call it a disease, I think of it as an extreme form of normal learning. “Disease” and “normality” are overlapping, not mutually exclusive, when it comes to the mind and the brain. Yet we sure recognize addiction as distinct from “normal” when we see it on the street.

That’s the problem -- the problem that befuddles the disease model. 

My solution will come several posts from now. Meanwhile, I hope readers will tell me whether my neuro-based argument makes sense.

 

(Please also visit my website for reviews and interviews related to my recent book, Memoirs of an Addicted Brain, and for direct links to Amazon for purchasing it.)

Marc Lewis, PhD has been a professor of developmental psychology and neuroscience for over 20 years and is the author of Memoirs of an Addicted Brain. 

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