NPR ran a fascinating feature yesterday about the new book by neuroscientist David Linden, The Compass of Pleasure: How Our Brains Make Fatty Foods, Orgasm, Exercise, Marijuana, Generosity, Vodka, Learning, and Gambling Feel So Good. With sex addiction all over the news these days, the book is a timely look at the purported difference between pleasure and addiction, namely that “the scientific definition of addiction is actually rooted in the brain’s inability to experience pleasure.” As is often the case with addiction studies, Dr. Linden seems to hedge his bets slightly by downplaying the proportion of addicts in relation to “Earth people.” That is, we might see addiction as a much more widespread affliction – which doesn’t make it any less dysfunctional or harmful, of course, just more common. While allowing for the obvious degrees of severity and circumstance, sex addiction, for instance, could be both real and universal. Because when you get under the surface, is anyone really playing with a full deck of cards in that arena? Certainly the insight about compassion holds water, regardless of where you stand on the compulsion/culpability scale – even if you embrace both ends at the same time:

“Any one of us could be an addict at any time,” Linden says. “Addiction is not fundamentally a moral failing — it’s not a disease of weak-willed losers. When you look at the biology, the only model of addiction that makes sense is a disease-based model, and the only attitude towards addicts that makes sense is one of compassion.”

Though it may be hard to be compassionate when addiction is used to justify inappropriate behavior, Linden argues that true addicts aren’t just resorting to vices because of desire. Rather than seeking pleasure, addicts are fulfilling a need. The case of sex addiction illustrates how this distinction can be confusing.

“Most people are understandably very suspicious of the whole notion of sex addiction,” Linden says. “They think this is something that philandering celebrities and their publicists make up as some way of excusing their anti-social behavior… The truth is that just liking sex a lot doesn’t make you a sex addict, and just cheating or engaging with prostitutes or other anti-social behavior doesn’t make you a sex addict. If you are a sex addict, just like a heroin addict … you are at the point where you are having sex not because you are deriving pleasure from it, but because you need to do that just to fall asleep at night and face the day, and not have withdrawal symptoms.”

So while true sex addiction is rare, Linden says, it is one of many very real addictions that stem from the way the human brain feels — or doesn’t feel — pleasure.

A couple of salient portions of the transcript:

[NPR Host Terry] GROSS: Now, you write that people assume that drug addicts become addicts because they derive greater reward from getting high than other people do. But you say the biology says no, drug addicts actually seem to want it more, but like it less. Would you explain that?

Prof. LINDEN: Yeah, I mean, I think it’s a very compelling notion not just for drug addicts, but also for any kind of addict – a gambling addict or a sex addict. Well, why are you an addict? Well, that person must really love getting high. That person must really love gambling and get so much pleasure out of it. That person must really love sex, more than the rest of us do, and so that’s why they’re motivated to do it more and more.

And the converging evidence from many different studies, both in humans and in animal model systems, is that it is precisely 180 degrees the opposite. That is to say, there are variants in genes that turn down the function of dopamine signaling within the pleasure circuit, that blunt the pleasures that are felt. And when you carry these gene variants, and you have a blunted dopamine system, a blunted pleasure circuit, the result of that is that in order to seek the same setpoint of pleasure that so-called normals would be able to achieve with moderate indulgence, you have to, on the other hand, overdo it.

In order to get to that same setpoint of pleasure that others would get to easily, maybe with two drinks at the bar and a laugh with friends, you need six drinks at the bar to get the same thing.

GROSS: Is that why a lot of people describe drinking, smoking, taking drugs as self-medicating?

Prof. LINDEN: I don’t know if that is entirely the reason, but it would be a reasonable explanation. In this case – I think when people use the term self-medicating, usually they are referring to something like dealing with stress in their lives.

GROSS: Why do you think sexually inappropriate behavior seems to be an attribute of men with power – whether it’s celebrity power, political power? And I don’t want to overgeneralize here, but there has been, lately… a kind of, you know, rash of these stories becoming public.

Dr. LINDEN: Right. I think the thing to keep in mind is that when you have genetic variation that gives you a blunted pleasure circuit, and this drives more pleasure seeking, novelty seeking and impulsive behavior, these are traits that are, to a certain degree, particularly in males, adaptive. These are some of the same traits that make people be innovators and leaders. And they also give rise to impulse control disorders, whether they are in the realm of drug addiction or sexual behavior or gambling. And these things are all comorbid.

So what I would say is that it’s not an accident. People tend to say, well, if you’re a man of power and you’re in this situation and you’re surrounded by people paying attention to you, telling you how great you are and eager to cover up for your mistakes, and that’s all true. But I think another contributor is that you are likely to have gotten to your position in part because of this novelty-seeking, compulsive personality that also sows the seeds of these particular antisocial behaviors.