Substance Abuse: The Disease of Addiction
Guest: Dr. Suzanne Thomas – Behavioral Sciences
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I’m Dr. Linda Austin. I’m talking, today, with Dr. Suzanne Thomas, Associate Professor of Psychiatry and Ph.D. in Experimental Psychology here at the Medical University of South Carolina. Dr. Thomas, I know that your area of interest is in addiction. We often hear the concept that addiction is really a disease, that alcoholism, for example, is a disease. But I think a lot of people don’t really know what is meant by that. When one hears those words, what does that really mean?
Dr. Suzanne Thomas: That’s a great question, Dr. Austin. It hasn’t been explicitly stated what a disease is, versus a disorder, or where it has been outlined by the NIH, for example. There are other conflicting views. So, when we say an addiction is a disease, what we want to get across to people is for them to better understand that addiction is a brain disorder, that there are organic changes that occur in the brain that underlie this problem, and we often have difficulty in communicating that.
No one has a problem accepting that cancer is a disease, or that cardiovascular disease and hypertension are diseases. But, it’s a stretch for us to consider that addiction is a disease, in part, because the behaviors that put us there, that put someone into an addictive state, were voluntary. That is, if you don’t take cocaine, or you don’t drink alcohol excessively, you won’t develop the disease of addiction.
That logic is faulty because, for the same you reason, you’d say, well, someone who has heart disease, if they didn’t eat fried chicken, or a diet of fatty foods, they might not have that disease. But we wouldn’t say, oh, therefore, heart disease is not a disease. So, people who abuse drugs or alcohol do put themselves at risk for the development of the disease. Once addiction occurs though, it’s no longer a voluntary decision whether that person can stop using the drug. That is, in fact, sort of, the underlying definition of addiction. That is, there is a loss of control over one’s willpower or over one’s ability to stop using the drug.
Dr. Linda Austin: Now, this is a technical question, but I wonder if there’s an easy way that you could explain what some of the brain changes are that occur when one becomes addicted, whether it’s to alcohol or another substance.
Dr. Suzanne Thomas: Yes. We have had just the most fascinating advances in neuroscience occur in the past ten years. And one of the most revolutionary advances has been brought about by our ability to image the living brain. So, neuroimaging techniques that we use here at MUSC, and in our research projects, have really allowed us to get a better view of what sorts of changes occur in a person who is addicted, versus one who is just, maybe, abusing that substance, or a control person who is not using the substance.
And the things that we see that occur in the addicted brain, there are two, sort of, major changes that occur. One is a change that occurs to what we call the motivation pathway. And these are neurons that are located sort of deep in the brain, in the limbic system, that help us feel things like hunger and motivation to go get something. For example, the very thing that makes food desirable to you when you’re hungry, the reason you get hungry and actually make an effort to go to the kitchen and find yourself something to eat and cook it, and all those things that drive you toward that behavior are due to activities deep in your brain and that motivation pathway.
Dr. Linda Austin: So, what happens then, in the motivation pathway, to somebody who is addicted?
Dr. Suzanne Thomas: Those neurons have become hypersensitized. In other words, when someone continues to use drugs and alcohol over and over, the neurons that are deep in that pathway become more like on a hair trigger, and the person is constantly motivated to get more and more, and more, of that drug. It’s similar to having a chronic hunger where you can’t get enough of it. That motivation is never abated. It’s never satisfied. It’s a constant drive. And that’s because those neurons, in that area of the brain, have been sensitized.
Dr. Linda Austin: Then, Dr. Thomas, is the increased sensitivity to motivational stimuli, is that specifically with regard to addictive substances? What happens to other sorts of motivations, say, the motivation to drive to work, for example, in the addicted person?
Dr. Suzanne Thomas: In the brain of the addicted person, pretty much, the main motive is to get more of the drug. And it’s not so much that the drug is highly pleasurable anymore; it’s not that. It’s not that they love the drug and really enjoy taking it. It’s that that motivation center has been sensitized to the need to have it. It’s, I have to have it. It’s not that I really, really like it. It’s that I have to have it to survive. And so, all other motives, the motive to care for your family, for example, or to go to work, or to, you know, enjoy other behaviors, or other activities, those things all take a backseat to finding a way to get more and more of the drug.
In addition to the sensitization of that motivation pathway that we just talked about, the other change that happens in people with an addictive disease, or addictive disorder, is that there are parts of the brain that feed back to that motivation pathway that kind of dampen it. It’s sort of like the brakes. And those are neurons, nerve cells, in your brain in the very frontal parts of your brain that project back down to the motivation pathway. And what that allows us to do is to make, sort of, pros and cons, weighing out decisions, like, okay, I really want that hot fudge sundae, but, while I really want that hot fudge sundae, if I eat it, I’m going to have to, you know, go to the gym two extra times next week or, I’m already full, maybe I shouldn’t eat it. That ability to weigh the consequences of your actions and the brakes of going to get something are controlled by neurons in this prefrontal cortex.
We don’t quite understand what happens in addiction, but we feel like there’s this functional disconnect between that motivation pathway and the brakes in the brain that allow you to say, okay, let me weigh the consequences of those actions. So, the problem with people with addiction is that they have this hypersensitive motivational state to go get the drug, and they have this dampened, or disconnected, system to tell them, okay, if I do this, I’m going to lose my family, my home, my job. Those kinds of weighing the consequences of actions are impaired.
Dr. Linda Austin: Like a heavy foot on the accelerator, but the car is going in the wrong direction and there ain’t no brakes.
Dr. Suzanne Thomas: That’s exactly right.
Dr. Linda Austin: Now, once a person, let’s say, becomes sober and has stayed sober for a period of time, let’s imagine, several years, do those physiologic changes ever go back to normal?
Dr. Suzanne Thomas: That’s an excellent question and research is really exciting in that area. We use to think that the brain did not regenerate neurons. So, once you killed neurons, for example, that was it. We now know that that’s not the case. The brain can regenerate new neurons, which is great news, and the brain can also keep existing neurons and, yet, allow them to work more efficiently. And what we know with people and addiction, who are in recovery, is that the longer your brain is in a clean environment, that is, the longer that you’re able to not use that drug, or alcohol, it’s giving your brain a chance to heal. And we begin to see changes as the person stays in recovery and is staying abstinent. We can image that living brain and see that it’s beginning to return to something that looks closer to a state of normalcy.
One caveat to that is that we haven’t yet been able to show that the brain of a person who is addicted, who is now in recovery, ever looks exactly like the same brain of someone who was never addicted. So, for example, one thing that research has shown is that a person who has been in recovery for a long time, abstinent for five of ten years, their brains are still more reactive to reminders of their drug of abuse than a person’s brain who was never addicted to that substance. One example is if we show a recovering alcoholic a picture of alcohol, or let them hold a glass of beer that was their favorite, or allow them to smell that cue, their brain reacts differently to that exposure, that reminder, of drinking than someone who has never become an alcoholic.
Dr. Linda Austin: Is that true in other areas where people have difficulty controlling their urges, such as eating?
Dr. Suzanne Thomas: We are beginning to understand whether there is such a thing as food addiction. There are several, you know, camps. And I think in the next five years, we’ll come to a closer consensus. Research will be able to show that, yes, you know, food addiction is an addiction. The changes that occur when you are craving food, for example, or actions that occur in the brain, if you can image that, are in the same areas that we see happen in addicts who are craving their drug.
The issue with food, as you know, is that everybody has to eat. So, if you’re trying to recover from cocaine addiction, your main goal is not to dabble in cocaine; don’t even use just a little bit of it, you need to stay clean and allow your brain to heal. However, we can’t stay clean from food. You have to eat two or three meals a day. So, it’s going to be a little bit more difficult describing food addiction and how to treat food addiction from a neuroscientific standpoint.
Dr. Linda Austin: One last question, most people who have had any connection or awareness at all of Alcoholics Anonymous, for example, or even people who have gone on a diet, understand that, in some way, if one can make kind of an all or none decision, you know, I am not going to have even one drink, not even a sip of alcohol, it’s a little bit easier than if you tempt yourself by having a couple sips and then try to stop. Does research on alcohol, as a brain disease, or addiction, as a brain disease, shed any light on why that is so?
Dr. Suzanne Thomas: We believe that when you dabble in it, as you were saying, just have a sip or two of alcohol, one of the things that happens in an alcoholic, because they have that sensitized motivation system, is that reminder of drinking further heightens that urge. So, it’s very difficult for an alcoholic, if not impossible, and there are conflicting studies about that, whether a recovering alcoholic can have a sip. Most of the studies show that, while they may be able to do that in the short term, it almost always, eventually, leads back into full blown drinking out of control. So, not priming your brain and offering that little bit of alcohol, which is a further reminder of how you’ve got to have it, is really the best way, as they say in Alcoholics Anonymous, try to avoid people, places and things that remind you of that substance.
Dr. Linda Austin: Dr. Thomas, thanks so much for talking with us today.
Dr. Suzanne Thomas: Thank you, Dr. Austin.
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