Addiction: The Role of Dopamine and Self-Control

INTERVIEWER: What's your poison, your addiction? Is it legal or illegal? Whatever it is you're hooked on, from coffee to cocaine, smoking pot to pigging out, Nora Volkow has your number.

She's the head of the National Institute on drug abuse. For three decades now, Volkow has been looking, literally, into the brains of addicts. Not just hard drug users, but smokers and over eaters, too. Nobody knows more about how we get hooked and why bad habits are so hard to break.

Dr. Volkow grew up in Mexico in a family with a famous ancestor and a tragic history. She's made history, herself, by challenging many of the old ideas about our addiction to addiction. What do you make of that common phrase, just say no?

NORA VOLKOW: If it were so easy, I think that we would have no problem of obesity, we would have no problem with drugs. I think that we have to be honest. We've all been in a situation where we were tempted by something, and we didn't want to do it, and we didn't have the self-control to stop it.

For example, I love chocolates. Everybody knows that. And I love also coffee. But I'm a very wired person, so I shouldn't drink more coffee.

But I sometimes I cannot resist it. And that is because not always I have the same level of self-control. So saying to someone, just say no, is magical thinking.

INTERVIEWER: Volkow's thinking has revolutionized how science and medicine now view drug addiction, as a disease, not a character defect. Her research pinpoints how drugs affect learning, memory, and above all, self-control.

NORA VOLKOW: We know that drug addiction is a chronic disease. It changes—drugs change the brain, physically change it. And those changes are very long lasting, and persist for a long period of time after the person stops taking the drug.

INTERVIEWER: She's been a pioneer in using MRIs, brain scans, to figure out the chemistry of addiction.

NURSE: Remain still and just relax with your eyes closed, OK?

INTERVIEWER: This subject is a recovering heroin addict, one of hundreds of drug abusers Volkow and her staff have examined over the years, zeroing in on a critical substance, dopamine.

NORA VOLKOW: Dopamine so happens to be one of the main chemicals regulating pleasure centers in the brain. And as such, it's therefore the mechanism by which nature motivates our behavior.

INTERVIEWER: At the most basic level, dopamine has saved us from extinction by making the key elements for survival of the species, food and sex, pleasurable. Dopamine send signals to receptors in the brain saying, this feels good. What is it, a hamburger?

NORA VOLKOW: It's a hamburger.

INTERVIEWER: Show a hungry person a hamburger, and their brain scans shows a dopamine rush.

NORA VOLKOW: It just basically stimulates release of dopamine. And the more they release, the more they want the food. We always say, well, why do we have a problem with obesity in our society?

And I said, my God, we're surrounded by stimuli with which we're conditioned. If you like hamburgers, you may see that McDonald's yellow arches, and then dopamine goes inside your brain, and you want it. And you don't know why you want it.

INTERVIEWER: And Volkow has found, images of alcohol and drugs produce similar signals, which the addict can't resist.

NORA VOLKOW: When a person is addicted, they get conditioned, just like Pavlovian dogs.

INTERVIEWER: During a brain scan, a cocaine addict was shown a nature scene. The image created no change in dopamine levels. The same test with a picture of someone using cocaine, result, a marked rise in dopamine.

NORA VOLKOW: Here in an addicted person, you're starting to get the conditioned stimuli—

INTERVIEWER: Just from a photograph.

NORA VOLKOW: Yes. from observing. And that's why drugs are so malignant. You see a stimuli, dopamine goes up in your brain, and that in turn drives the behavior of the person to try to get the drug. And that's an unconscious thing. It's not even conscious.

INTERVIEWER: Her budget reflects the urgency of the work, a billion Dollars a year for a wide array of research projects. She was the first to demonstrate how cocaine can damage the brain by triggering small strokes, and she's identified a common trait most addicts share involving receptors, the molecules that receive dopamine signals.

NORA VOLKOW: We're seeing consistently a reduction in the levels of these dopamine receptors. In this case, heroin, alcohol, methamphetamine, cocaine, but also marijuana and cigarette smokers.

INTERVIEWER: The problem is, the brain just isn't wired to handle the intense high that drugs give. A kind of shut off valve kicks in, reducing the number of receptors in the brain that receive dopamine's feel-good message.

NORA VOLKOW: What happens with repeated administration of these drugs is that the ability of them to generate the sense of pleasure decreases, and decreases, and decreases. And there's a point where the person starts to take them, not to feel good, but to feel normal.

INTERVIEWER: There is that school of thought that says, look, all you need is to be strong willed. Your problem is, you're weak. Show some determination, and you can beat this addiction.

NORA VOLKOW: There are certain areas of the brain that are directly implicated in our capacity to exert free will. The frontal cortex is one of them, crucial, crucial. So if drugs damage the areas of the brain that we need in order to exert free will, then it's like driving a car without brakes. You don't want hit someone, but if you don't have brakes, how do you stop the car? One of the areas that's most sensitive to marijuana is the areas with memory and learning.

INTERVIEWER: Volkow pays particular attention to educating teenagers about the harsh realities of addiction. Her agency does a yearly survey of their drug use. The good news is, there's been a continuing decline in smoking and drinking. The not so good news, marijuana use remains high, with one out of three high school seniors surveyed saying they've smoked it in the past year. And the really bad news is the massive increase in both kids and adults using prescription painkillers to get high, mainly Vicodin, OxyContin, and other opiates.

NORA VOLKOW: You know how many prescriptions there were for opioid medications last year in this country? 210 million prescriptions for opioid medications, 210 million prescriptions in one year.

INTERVIEWER: That's enough pain pills to keep every adult in the country medicated 24 hours a day for a month. There's been a huge spike in hospital emergency cases, and the overdoses from pain pills kill nearly 15,000 people in a year's time.

NORA VOLKOW: Either we are a nation on severe pain, or we're over-prescribing.

INTERVIEWER: When doctors prescribe these very powerful pain medications, do they know what they're doing?

NORA VOLKOW: Being honest, I think that many physicians have not been properly trained on how to prescribe opiate medications.

INTERVIEWER: Even as a teenager at Mexico's National University, Volkow herself was no stranger to the heartbreak addiction has caused to so many families. Addiction research became an obsession.

NORA VOLKOW: And I had seen that actually from my own family, because on my mother's side there is a family history of alcoholism. And it was never considered that my uncle had actually a medical disease, itself. And therefore, he never received the help that could have benefited not just him, but his family.

INTERVIEWER: And looking forward down the road, she sees a day when science might banish the curse of addiction.

NORA VOLKOW: A cure would be fantastic. And that means you get a medication, like an antibiotic, I cure you.

INTERVIEWER: Volkow's labs, and others around the country, are working to develop vaccines to block drugs from entering the brain. The complexities are enormous, and progress is slow.

NORA VOLKOW: We're not there yet, but perhaps one day we may be. And in my brain, if you don't dare to think very ambitious things, you'll never be there.