MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Dr. Nora Volkow is director of the National Institute on Drug Abuse at the NIH. As one of the nation's leading experts on addiction, she studies how drugs affect brain function. Dr. Volkow joins me in the studio to talk about addiction and how we can better understand what she terms a chronic disease. Throughout the hour, we'll take your calls, 800-433-8850. Do send us email to drshow@wamu.org. You can join us on Facebook or Twitter. Good morning to you. It's good to have you here.

DR. NORA VOLKOWGood morning, Diane. Thanks for having me.

REHMI'm so glad you are here. The notion of addiction as chronic disease rather than moral failing, talk about how you reached that conclusion. It must have taken you quite a while.

VOLKOWWell, that conclusion stems from science, from research that has been done over the past, I would say perhaps 20 years, that has shown that repeated drug administration produces changes in the brain. It changes the brain in ways that lead to the compulsive pattern of administration of the drug despite its very adverse consequences. So these findings have come out of research in laboratory animals, but also from brain imaging studies that allow you to look inside the human brain and see how the repeated use of drugs can affect its functions, and how that in turn can result in this behavior that is so destructive for the person that's addicted, but also for his or her surrounding environment.

REHMAnd of course, dopamine is very much involved.

VOLKOWYes. Dopamine is a central player because it mediates the required responses of the brain. So when the brain is exposed to a stimulus that a pleasurable rewarding, it activates dopamine pathways and that triggers a cascade of neuronal events that can increase the likelihood that that individual will seek that particular stimulus. And so that is mediated by dopamine which provides the motivation, the energy, to want to do that particular behavior again.

REHMSo are you saying that the person who becomes addicted has low levels of dopamine to begin with?

VOLKOWWe don't know. We speculate that some people will be vulnerable because they may have to start with low dopamine levels, but we also know from animal experiments that the repeated administration of drugs can decrease dopamine signaling in the brain of laboratory animals. So it appears that both situations are possible, that there may be individuals that because of genetics or developmental factors, have low function of the dopamine brain pathways, and on the other hand, it is also possible that individuals may not have not had that vulnerability, but with repeated drug use, that decreases brain dopamine signaling.

REHMSo take a mouse for example. With repeated injections of some form of drugs, are you suggesting that the level of dopamine may decrease requiring repeated injections of that drug to take the dopamine back to a normal level?

VOLKOWIndeed that is what researchers have found, and not just in rodents, rats and mice, but also in non-human primates. That repeated use of drugs weakens the brain dopamine system, and that has led some to postulate that that is the reason why people take drugs, because they want to compensate for that weakened dopamine system, and that leads them to want more and more and it is likely that there is some truth on that hypothesis, but it's actually more complex than just the deficit in the reward dopamine system.

REHMCan you actually measure dopamine by the imaging process?

VOLKOWYes. We can use imaging to directly assess the function of the dopamine system, and so for example for many years, me and my colleges at Brookhaven National Laboratory have been studying the dopamine system in people that are addicted to a wide variety of drugs, cocaine, alcohol, nicotine, methamphetamine, and we have shown there's a consistent pattern that there is a deficit in dopamine signaling in the brain of people that are addicted to drugs.

REHMSo what happens to the brain when, say, cocaine is taken in?

VOLKOWWell, when cocaine is taken in, it goes into the brain very rapidly, and it directly interferes with the protein that recycles dopamine back into the cells, and -- and this protein, which is called a transporter, terminates the action of dopamine. Since the transporter is not working, dopamine accumulates and that strengthens the signal in reward pathways that is experienced as very, very pleasurable by people that take cocaine.

REHMSo the brain becomes conditioned, and what that means is that it gets used to a certain amount of whatever the drug is?

VOLKOWWell, yes. You are touching on a topic that is making me smile, which is conditioning, because conditioning is at the essence of addiction and reward. When you get a very high surge -- we call them surges, in dopamine in the brain, that activates memory pathways that lead to what we call conditioning. So conditioning in neuroscience is what Pavlov studied with the dogs, where an animal will salivate when they hear the sound of the tone. That animal has been conditioned to expect a reward from the sound of the tone, and that's exactly what drugs do in the brain, because they have such a potent effect in activating dopamine systems.

VOLKOWSo as a result of that, the brain learns to get conditioned to stimuli that predict that drug. So for a cocaine abuser, that may be the syringe he or she uses to inject the drug. It may be the drug dealer. It may be the $20 bill they use to inhale it. And when they see these stimuli, automatically the brain liberates dopamine, even before they take the drug. And as a result of that release of dopamine when they seem the stimulus, that is associated with a very intense desire to take the drug.

REHMWouldn't it be marvelous to be able to go back to the first humanoid and to conjecture what it was that turned that human on?

VOLKOWWell, I think that we can speculate because actually we know every time a newborn is born, it's -- that newborn has not yet had the big influence of civilization, and what is a first newborn motivated by? It's motivated by the sweetness of the mother's milk, and that is highly, highly rewarding. And that activates dopamine pathways and conditions the infant to the smell of the mother and to the touch of the mother because it predicts the milk that has the reward, the sweet, and so we can predict that these rewards circuits are actually -- which are preserved across species, and crucial for survival, may have been a mechanism by which nature ensures that we do behavior that are indispensible for survival of the individual, but also for survival of the species.

REHMWell, and of course now you've gone to mother's milk. What about ordinary food and how the sight, the smell, the taste of food itself may become addicting?

VOLKOWWell, what is evident is obviously that our brain did not evolve over years and years of evolution for us to take drugs. What's happening is that drugs are tapping, and I would say almost by randomness of nature, into the circuitry that was developed by nature to ensure that we will eat the food when it was available. So it's, therefore, not surprising now that we have these societies where very palatable food is widely available, that we're seeing individuals become compulsive about their food intake and unable to control themselves even though they know that it's adverse, even though they don't want to eat more.

VOLKOWAnd I think that more or less all of us in one moment in our lives where we are faced with that difficulty of self-control not to overeat. So yes, indeed, we are starting to realize that the way that nature regulates, for example, homeostatic signals to tell you how much to eat, depends on eat regulating the reward circuitry. So hormones that normally are associated with energetic like insulin, leptin, they modulate directly the brain dopamine reward circuitry. So when these signals are stating you are energetically deprived, then the reward dopamine system is more sensitive to food stimuli, and that then makes you much more motivated to seek it.

REHMAre you then, and I don't mean to put words in your mouth, but are you equating the rationale for overeating with drug stimulation?

VOLKOWI'm not equating it, but I'm basically going to the fundamentals of how our brain is hardwired. Our brain is hardwired whether we like it or not, to seek rewarding experiences, to seek pleasure, and to avoid aversive stimuli. And as a result of that, as humans, we're prone to take rewards, such as food (word?) .

REHMDr. Nora Volkow. She's director of the National Institute on drug abuse at the NIH. We'll talk further after a short break, and take your calls.

REHMAnd if you just joined us, Dr. Nora Volkow, who's director of the National Institute on Drug Abuse at the National Institutes of Health, is with me and we're talking about the topic of addiction and whether it applies to drugs, whether it applies to food, whether genetics play a role, why adolescents seem to be more vulnerable. Those are our topics we hope to get to and, of course, to your calls, as well. We talked about that transmission of mother's milk and, of course, the role that closeness plays, the smell, the sense of that loving human being next to us. But that milk passing through also is affecting how that human being reacts to a great many things, Dr. Volkow. What about genetics as it plays in the role of addiction?

VOLKOWIt is very well recognized that the genes play an important role in the vulnerability of addiction. And we know that addiction runs in families so no one would question it. In fact, you can generate mice or rats by breeding them for preferences of alcohol or cocaine. That will then selectively administer these drugs and you know that you have passed some genes to these animals that make them vulnerable for taking these drugs.

VOLKOWWell, we do not know yet is actually what are the genes that are involved in that vulnerability. We have some indications of genes that play roles, but it's an area that is still not completely understood that would be very, very valuable because if we could understand specific genes that make you vulnerable for addiction, that could guide us towards therapies that could be developed.

REHMAnd do you see that adolescents are more vulnerable perhaps because their brains are not yet fully developed?

VOLKOWYes, indeed. And empiric logical studies have corroborated these for many years. Most individuals start to experiment with drugs during late childhood or early adolescence. And most of them will transition from drug experimentation to addiction in late adolescence, young adulthood. So you see most of the pattern of drug use emerging at late adolescence, young adulthood. And this is believed to relate in part to the fact that the brain of an adolescent is different from the brain of an adult. It has not been fully developed.

VOLKOWAnd there are many differences. And one of the most important, it is believed, is the fact that the brain of an adolescent is not fully connected. And as a result of that, for example, that connection between the frontal cortex that allows you to exert self-control and limbic brain which is responsible for your emotions and desires is not fully formed. And that puts the adolescents at a tremendous of not being able to inhibit urges that may result from the fact that they want to do something very much or because they are activated by a very strong emotion. And that, in turn, puts them, of course, at risk of experimenting with drugs.

REHMSo what constructive role can parents play knowing that that is in fact the situation?

VOLKOWTo start with a parent cannot be too self confident that their kids will not take drugs. And I've seen that too many a time. That parent says no, of course my child will never do this. And I would say never be over confident. All adolescents are at greater risk for substance use disorders. And there are many mechanisms that can increase this vulnerability that are not just as simple as them wanting to have fun. They may be at greater risk from peer pressure, for example, and they want to be cool and they feel that others are taking them and they don't want to be different. So they may take them that way.

VOLKOWIn other instances, adolescents may be trying to feel better because they may be suffering from a mental disorder or a learning disability and they are taking drugs as a means to try to compensate. So adolescents are at greater risk and parents should be attentive to this and not be over confident.

REHMParents should be aware. But of course, you're talking as far as adolescents are concerned not only about drugs, also about food and perhaps, Dr. Volkow, about sex. And not just the adolescent there, but I'm bringing sex into the question of addiction.

VOLKOWWell, sex is another very rewarding behavior and again, it's the mechanism by which nature ensures that the species would survive. So if we didn't have the drive and the motivation that is linked with such intense rewarding experiences that also condition you because they condition you to the person. When you are experiencing a pleasurable response, you are conditioned to that individual, which is, of course, extraordinarily important for the survival of us humans since the formation of couples increases the likelihood that the infant will be born.

VOLKOWSo these are very fundamental biological processes by which nature ensures, not just in humans but across animals, that there would be these behaviors that are motivated to sex so that they can procreate and also seek the food that will allow them to survive. Now what happens in adolescents -- so you have this adolescent brain that is not fully formed and all of a sudden there is this transition where hormones start to actually rise. And that leads to activation of limbic areas of the brain that will make them actually much more prone to really literally falling in love with someone else.

VOLKOWIt's also the hormones that are playing a role. And this in turn can lead them to do behaviors that on the long term could be harmful to their own prospects. And so these are situations for which all adolescents are faced with and parents need to be aware of them and discuss it with them and provide them with strategies and behaviors that can protect them against them making a wrong decision.

REHMNow I'm going to ask you a very controversial question about which a great many people have called this program stating that marijuana should be legalized or decriminalized because it is not addictive or that it is no less addictive than alcohol. What is your thinking about that?

VOLKOWYeah, I've been asked that question many times and I'm going to say, well, we know now unequivocally that marijuana is addictive. Now not all of the drugs have the same potency for addiction. Some are more than others. So methamphetamine is probably much more addictive than marijuana. But marijuana is addictive. Now the argument of saying it's less harmful than alcohol or not -- I'm not going to go into that argument because you can put statements on either side.

VOLKOWAlcohol is a main reason for death about young people because of car accidents. So the mortality and morbidity associated with alcohol is quite gigantic. Particularly if you consider that it's affecting young people. The other big killer of the drugs is nicotine. And nicotine in the world kills 45 million people every year. 45 million individuals. Now, is it because these two drugs, alcohol and nicotine, are the most dangerous or more addictive? No, not at all. They are less addictive and they are less dangerous than something like methamphetamine or cocaine.

VOLKOWSo why that drives these sky levels of mortality and morbidity, because they are legal and because they are widely available. And the availability increases the probability that people take them and that increases the probability that they will end up with adverse effects. So my answer is, you have two big killers, alcohol and nicotine. Do you want a third?

REHMUm-hum. And what about prescription drugs?

VOLKOWPrescription drugs is a really serious and tragic problem that we're facing as a nation because it's widely abused and it's abused at all ages, not just young people. We're seeing, for example, abuse of pain medications in middle age and even senior citizens. Now there are three types of drugs that are favored, pain medications that have opioids. Stimulant medications like Ritalin and amphetamines and then benzodiazepines like Valium. And they are abused because they can produce rewarding effects. They activate the dopamine system.

VOLKOWThe problem is particularly urgent though with pain medications because they are quite dangerous and they are accounting for a significant increase in the deaths from overdosing. So in more than 30 states in the United States there are more people that are dying from overdose from pain medications than from car accidents. And I think that these numbers really highlight how serious a problem it is in our country.

REHMCan you estimate how many people in our nation are addicted to drugs?

VOLKOWYeah, there are multiple estimates about people that are addicted to drugs. And for example if you take nicotine it is estimated that between 18 and 20 percent of the adult population is addicted to nicotine in our country. With alcohol which is the second one most frequent the addiction numbers are approximately 3 percent. But a higher number, close to 10 percent, may have a problem with alcohol abuse. And when it comes to elicit substances those that are actually addicted to elicit substances may be approximately again 3 percent of the population.

REHMThree percent is a fairly small number and yet you are, I gather, working toward finding a cure.

VOLKOWYes. But 3 percent is not a small number. Those are the ones that are addicted actually and for elicit substances so we cannot forget licit ones where the numbers actually ramp up. But yes it is extremely important that we get treatments for drug addiction whether they are legal or illegal. It doesn't matter. We need treatments. We need better treatments. People are dying in this country because of the lack of effective treatments.

REHMWhat kinds of treatments are you looking at?

VOLKOWWell, when we look at treatments, we have two strategies and I always divide my brain in these two aspects. Are there treatments currently that are available that could help people right now with the knowledge that we have but that are not implemented? That's one side. And then the other side is can we use science to develop treatments that are going to transform the way that we treat addiction say five to 10 years from now?

VOLKOWSo that the really devastating consequences of this disease need not be. Like, we have made major advances for the treatment of HIV so we can use that as an example. So if we can use science to translate into medication, there's no reason why we shouldn't be using it for addiction, in fact. I think that we have that responsibility to do it.

REHMDr. Nora Volkow, and you're listening to "The Diane Rehm Show." Are there any treatments available today?

VOLKOWYes, there are and we have actually behavioral intervention that help people be able to stop taking drugs. We also have medications that help people stop taking drugs and unfortunately we only have medications for alcohol, nicotine and opiates like heroin or pain medications. But we don't have medications for marijuana. We don't have medications for cocaine, for methamphetamine, for the stimulant drugs.

REHMHere's an email from Chuck in Cincinnati, Ohio who wants to know "are the same areas of the brain affected by gambling addiction as with drug addiction?"

VOLKOWThere is an overlap actually we've been able to realize between drugs that have rewarding effects that produce this compulsive patterns and behaviors that are rewarding that produce these compulsive patterns and at the center of this is the brain dopamine reward pathways. All of these stimuli, whether they are drugs or gambling or very palatable food activates the dopamine reward pathway.

REHMSame process?

VOLKOWSame neuronal circuitry. One of the things that clearly, though -- I mean, I want to make this point -- is drugs are very, very potent and activate them and that's why if you get exposed to certain drugs your risk of becoming addicted can be very high. Food, very palatable food, can also be very rewarding, but fortunately it's not as potent and as a result of that, even though many of us, all of us, have got to eat in order to survive and we get exposed to this wonderful food, very few of us lose complete control over our food intake.

VOLKOWSo that gives you a sense that drugs are much more potent in disrupting these dopamine reward pathways. Gambling can disrupt the dopamine reward pathways, sex can disrupt the dopamine reward pathway. Videos. Video gaming, for example, has become very problematic in certain parts of the world because kids become so compulsive that they forego sleep and they stop doing their homework so all of these behaviors can ultimately, in those vulnerable, lead to compulsive patterns.

REHMAnd here is an email from Ann in Bradenton, Fla. "Does the doctor include sugar as a drug?"

VOLKOWWell, of the foods that are highly rewarding and I like to speak about in terms of what makes us overeat and that's important because that is one of the main factors driving obesity, that there is an addictive dimension to food. And that highly palatable food, particularly that which contains sugar, glucose and fat is particularly powerful as a reward. And for example, in animal models, you can make animals consume huge quantities of calories if you expose them to food that is rich in fat and sugar.

VOLKOWYou won't be able to do that if you expose them to their regular chow. You will not be able to make them obese. But if you expose them to sugar and fat, you will.

REHMIt's surely the same with humans?

VOLKOWWell we have an epidemic of obesity.

REHMExactly.

VOLKOWAnd it is the fact that we're exposed to this food that is widely available, very, very cheap and very difficult to resist. I mean, actually sometimes I say -- I mean, I constantly have to be inhibiting the urge of eating these fantastic foods. Particularly because everybody knows that I love chocolate so they give me all sorts of very tempting chocolate. So I have to exert self control and say no, I'm not going to eat it.

REHMDr. Volkow, you're not alone, I promise you. Dr. Nora Volkow, director of the National Institute on Drug Abuse at the NIH. Short break. We'll be right back.

REHMAnd welcome back. Dr. Nora Volkow is here to answer your questions about addiction. Let's go first to Harrisburg, Pa. Jim, so glad to have you with us.

JIMWell, thank you for having me.

REHMGo right ahead, sir.

JIMDoctor, I spent a lot of time in the software industry specifically for EMR EHR software first editions, but more specifically in the physical medicine vertical which also encompasses addiction medicine. And what I find is physical medicine and rehab doctors are prescribing copious amounts of opiates legally to their patients, 150, 200, 250 tablets of very powerful narcotics per month. And then on the flipside I go to the addiction medicine doctors' offices and they're getting these very same patients off of those opiates. And then I wanted you to kind of address that.

JIMBut then secondly you just touched on what medicines we have available to help people with addiction issues. And, yes indeed, there are medications out there to get people off of opiates. And I don't want to name the brands, but of course we -- but that we have them available. But what's important, from what I've learned, is it's great that the doctors can prescribe these wonderful drugs, but without a behavioral health component to the treatment, the failure rate is close to 80 percent.

REHMAll right, Jim. Tell me what station you're listening on.

JIM89.5.

REHMAnd that is WTIF?

JIMWITF.

REHMAh, WITF, one of our newest affiliates. So glad to have you. Dr. Volkow.

VOLKOWYeah, you're touching on something that has definitely attracted the attention of multiple agencies, the recognition that there has been a very significant increase in the prescription of opiate medications. In fact in 2010 there were more than 200 million prescriptions for hydrocodone and oxycodone. And these reflect on the one part the fact that more physicians may be willing to treat pain with opiate medications. But also it does reflect the other one that some individuals may be over-prescribed these pain medications. And some of these pain medications are being diverted and abused.

VOLKOWNow at the essence of what is the nature of the problem is, well, we have a very difficult situation because pain can be devastating and we don't have so many alternate medications. And opiate medications can be lifesaving, but they can also be very addictive and that's why we are in this conundrum. The issue is to try to understand better when are opiate medication really needed as opposed to when alternative medications and algesics should be used.

VOLKOWAnd as you mentioned, what other behavioral interventions may be appropriate for managing the pain as opposed to relying solely on the use of pain medication? So one of the initiatives that we are doing at the NIH is to develop a series of centers for the development of curriculum to the screening on proper management of opiate medications to train physicians, to train nurses, to train pharmacists to try to obviate and control this problem.

REHMJim, thanks for your call. Here's an email from Careen in Oakton, Va. "Are children who take stimulus for -- stimulants for ADHD at higher risk for addiction?

VOLKOWAnd that is, again, a question that a lot of scientists have tried to address including -- I have worked on that particular question. And the data is -- basically as of now indicates that the use of stimulant medications like methylphenidate or amphetamine in children with ADHD does to increase the risk for substance use disorders. But the other -- the data also shows that it does not either decrease or increase. So it's -- because at one point there were researchers that were saying that treating will decrease the risk. So the data shows that there's no evidence that it either increase or decreases.

REHMAll right. To Dartmouth, Mass. Good morning, Bill.

BILLGood morning and good morning, Dr. Volkow. I'm an incredibly big fan of yours. I work in the field. I'm a clinical director for a company that provides treatment services in Massachusetts. And I've read your -- read some of your stuff. Also, I believe I've met your father when he was taking a political tour through the United States about 20 years ago with Pierre Brule.

BILLBut I wanted to ask you if you would talk just a little bit about treatment strategies in the United States. And why when a country like Portugal goes to figure out what kind of detox or what kind of methods they want to use to help people defeat substance abuse, do they say that the absolutely only system of treatment that they would not adopt would be what we practice in the United States? Some of the issues around abstinence versus harm reduction, could you mention a little bit about that and what strategies you think do work?

VOLKOWI will, but I cannot stop at the fact that you mentioned Pierre Brule because Pierre Brule has been, of course, a long friend of my family. And unfortunately he passed away two years ago so yes, you probably were speaking correctly about my father.

VOLKOWWith respect to treatment strategies, one of the things that I've always been very critical of the way that we address the treatment of substance use disorders is that we've polarized the field into believing that it's either this or that. My perspective is that addiction is a terribly devastating disease and that we need to be aggressive, just like we're aggressive with the treatment of cancer. And rather than stating this or that, we should say this and that.

VOLKOWAnd that includes, in my view, and again one of the big initiatives that we have at the National Institute of Drug Abuse is how do we involve the health care system in the screening for the prevention and treatment of substance use disorders because overall the health care system in the United States has really not been involved in the prevention or treatment of these disorders. And as a result of that, we've lost an opportunity that could really make a big dent in the right of substance use disorders in our country.

VOLKOWAs for your question about in terms of should we just be aiming for abstinence or should we also include alternative strategies, in my perspective is, of course I love the idea. I'd love to have no drugs. I'd love for that person not to be taking any drugs. But if we cannot lead to complete abstinence, my perspective as a physician is what can you do to help that individual. And in that -- in many instances maybe to do an intervention that minimizes the harm that that person is getting from the use of drugs.

REHMWhat kind of intervention?

VOLKOWFor example, if you were to have an intervention that, while not being able to produce full abstinence in a person that's addicted, may decrease the amount of drugs that they are taking to 20 percent of their usual consumption or 50 percent. That would be very valuable. So I think that by setting the bar so high or for treatment that would only produce abstinence we are really jeopardizing our ability to help individuals that would benefit if we could decrease their consumption of drugs, even though they may be taking them once in a while. Not ideal theoretically, but that is many of the circumstances where many patients face themselves.

REHMBill, thanks for your call. To Wesley in Jacksonville, Fla. Good morning to you.

WESLEYHey, good morning. Thanks, Ms. Rehm. I'm a big fan of your show.

REHMThank you.

WESLEYAnd I hope my candor offers a lot of insight to your listening public. I am a textbook example of a hardcore addict, however I've abstained from drugs for the past 17 years. And even still today, my body still craves drugs. So I wanted to ask your guest, am I like other addicts just -- are we just, like, doomed or do we just have faulty brain circuitry or is there a point where so our brains just stop craving it? 'Cause I stay clean 'cause I follow a strict routine life. Like, I have to do everything every day at the same time. But even 17 years I've been clean, I still sometimes fantasize about that pleasure I get from using illegal drugs.

REHMWesley, congratulations to you for resisting that temptation for all these years. Dr. Volkow, what do you think?

VOLKOWWell, first of all, I also want to congratulate you and for your courage to be able to speak out because...

REHMExactly.

VOLKOW...we need to show that it is possible to beat addiction. And what you are describing is exactly why we call drug addiction a chronic disease. And the changes that are produced in the brain by drugs are long lasting and persists years after the person has stopped taking the drug. And that's why you still have the cravings. And if you are in an environment that could -- where you have been exposed to cues about the drug, that could exacerbate them.

VOLKOWAnd what you're doing is also one of the strategies that is promoted by treatment programs, which is to develop a routine in your life that allows you to give you alternative behaviors or reinforcers that can help you overcome the strong desires to take the drug.

REHMSo are there perhaps any medications that Wesley could take now which might somehow mitigate that craving that he feels he still experiences?

VOLKOWWell, at this point -- I mean, not knowing the details, but I think that he has been very, very successful. Seventeen years of sobriety is quite wonderful and I wouldn't want to mess with that. So I would say just keep doing what you're doing because it is a very good example. And I would like to be able to see other patients come there. And because most patients relapse within six months than in those ones I would say is there something? Is a medication that we could develop that could help them, for example, inhibit those cravings and conditioned responses?

VOLKOWAnd this is indeed some of the research we're currently funding at the National Institute on Drug Abuse. Medications that can inhibit those -- the craving that results from being exposed to conditioned cues.

REHMAnd 17 years out, will the craving continue to diminish?

VOLKOWWell, in principle, it is believed that the longer you've been able to stay without drugs, the less powerful the craving is after a certain period of time. But there's tremendous variability between individuals so, for example, there are individuals who will keep on craving all their lives even if they've been 30 years sober. Whereas others, the craving disappear faster, which again highlights how diverse the nature of addiction is.

REHMWesley, again, our congratulations. Thank for calling. One of the earlier callers mentioned your father. You are the great granddaughter of Russian revolutionary Leon Trotsky. You grew up in Mexico in the home where he was assassinated. How aware were you of this when you were young?

VOLKOWWell, I was aware since I have a recollection because I grew up in the house where he had been killed. And we all knew this. And, too, my father was -- and both my parents were very particular about the sense of a social obligation that we had our responsibility with our lives to do something that would be helpful to humankind. So I was brought up in an environment where social responsibility was something that each one of us should carry forward with the best of our abilities.

REHMDid your parents try to protect you from those memories?

VOLKOWWell, my father clearly -- and I say my mother following that -- tried to protect us from going into a career of politics. And I think that because my mother also lost her family in the Spanish Civil War, both of them had suffered the really tragic consequences from war and from politics. And so as children, we really -- there was almost like not an open prohibition, but politics was not something that was discussed at the dinner table.

REHMNot even discussed.

VOLKOWNot as children, no. And for many years, we -- until actually I was in medical school we were -- my father was very reticent to speak about his own life with Trotsky. And so we didn't dare to ask him questions as children. This was almost like a taboo topic. So what we learned we learned from reading and it was (unintelligible) extraordinary curious person, I would spend hours and hours in the house where Trotsky had been killed. And I would read the newspapers and I would read his books. And we would get visitors come to see the house and we asked them questions. But I never asked my father.

REHMYou never asked your father. Do you now wish you had?

VOLKOWWell, now I do, I do. I mean, actually my father is -- 'cause I think he has come to terms with the losses and I think that over the past 25 years he had started to speak more and more. And I was very lucky to be with him in Paris when he came back for the first time to the apartment where he had lived with Trotsky's son, his uncle, until he was killed. And they removed him from that apartment and from Paris. They took him away. So he was returning to that place and I was with him. And then I asked him. I asked him many of the questions I have never dared to ask him.

REHMAnd did he respond fully?

VOLKOWYes, he did, he did. And I remember asking him very specifically, do you remember your mother because my father was very young when her mother -- she was with her mother, but her mother committed suicide. And I mean, how devastating can that be? And I never got there to ask him that question.

REHMAnd even now that affects you and I can certainly understand that. Well, you not only have a fascinating background, you have a fascinating life ahead of you as you work so diligently to find answers to these very complicated questions. Dr. Nora Volkow, thank you for being here.

VOLKOWThanks for having me.

REHMShe is director of the National Institute on Drug Abuse at the NIH. Thanks for listening all. I'm Diane Rehm.