Neuroscience Discoveries And Their Impact

By Michael J Kuhar Ph.D

There have been many important discoveries in the neuroscience of drug abuse. These have had a big impact on how we treat and understand drug abuse, and I would like to address some of these. My views could be arguable, but they are reasonable and based on many years of study.

We have always known that drug abuse is a highly relapsing disorder. This makes it seem like drug abuse is inevitable and unending. But this is not so. Brain imaging studies have shown that it is not always unending; it just takes a long time for the brain to heal. When the levels of an important brain chemical called “the dopamine D2 receptor (D2R)” are measured in the brains of users who are at various stages of abstinence, we find that the newly abstinent users have lower levels of D2Rs. But this changes. The longer the user is without drugs, the more the levels of D2Rs return to normal. This receptor in the brain is there for the chemical dopamine, an important substance that modulates feeling good or reward.

But the hitch is that the return to normal takes a very long time – months or years. There is evidence that the rate of return varies with the individual. So, we have to cope with the fact that healing takes a longer period of time than most can spend in rehab.

Instead, we need to develop ways, approaches, or techniques that allow some form of treatment to extend for a long time.

It’s more like a lifestyle change. The particulars of this are left up to the user and his or her treatment professionals. Getting everyone onboard with this duration issue has to happen before we can realistically address the problem.

Does extended drug use change the brain forever? Is it that once you are a user, you are always a user? Some researchers might think so, and others think no. I’m one of those who do not think so because the brain imaging data do show a return towards normalcy as was mentioned previously. Also, there are many long term users who give up certain drugs forever or for a very long time. In those cases, if the brain was changed forever by drugs, the change was not very impactful. However, because of individual variations, there may be some users who are changed forever. But, we don’t have any evidence that proves this one way or another for everyone, at least not right now. We already know that some users may require help and guidance for a long time. Overall, studies show that treatment works, and the longer treatment is given, the better.

Let’s move on to another issue. Why does addiction occur? Why hasn’t evolution “weeded” addiction out of the human race? After all, by definition, addiction has negative consequences on our lives. A set of advances in many areas can help us look at these questions. First, we need to look at the brain as a survival organ. Whether we realize it or not, the brain guides or at least nudges us to carry out behaviors that are good for our health and survival. It guides us by making us feel good after activities such as eating when hungry, drinking when thirsty, or mating to have offspring. These “feel good” responses of the brain are crucial, because without them, our survival as an individual or species might be seriously threatened.

A key thing here is that this is also how drugs work. They turn on our feel good systems in the brain. The brain becomes an unwitting co-conspirator in the addiction process because it can’t combat drugs in the brain very effectively. Feeling good every time we take drugs is a powerful reinforcer of our behavior.

Reinforcing means that it causes us to want to do it again. Drug taking, for these reasons, is very powerful. In this view, the brain reinforces drug taking because it is interpreted as something important for survival.

Before we can get the big picture, we need to realize that people are different. While we are all people with 46 chromosomes, we are all different in sometimes significant ways. Some have higher IQs than others. We all look different. Some are tall and others not so tall. This is, in part, because our genes are slightly different. We all have the genes needed to be a human, but, because of mutations and environmental influences; the power or effectiveness of each of our genes can vary. Just as some of us are prone to cardiovascular disease or asthma or diabetes, some of us are more prone to having problems with drugs.

So where does this leave us? We have a brain that, because of the way it functions to reward survival based activities, allows drug abuse and addiction. The brain can repair itself (return to normal) when we stop taking drugs, but this takes months or years. We all have a slightly unique gene pool and slightly unique environmental experiences that leave us all with different vulnerabilities to take drugs. It seems complex. Can we make sense of this?

Well, perhaps we can. We need to accept that some of us end up in trouble with drugs. If somebody is already an addict, then they know what to do. They need to find a way to get off drugs and/or minimize the damage they cause. To do that, they likely need the help of a professional. It can be a long battle. If you are worried that you or someone you know or are related to may become or is becoming an addict, then you need to assess your vulnerabilities. Are you worried about a genetic load or predisposition to drug use? Are you in a difficult environment where drugs are freely available? These vulnerabilities need to be assessed, perhaps with a professional, so that your behavior can be adjusted to keep you safe.

Drug abuse can be as complex, long lasting and as complicated to treat as cardiovascular disease, asthma or late onset diabetes; treatment can encompass a number of activities that include behavioral and life style changes as well as taking medications. None of these diseases are easy to deal with and the vulnerability to get sick may always be there. They require awareness, vigilance and a persistent effort.

Michael J Kuhar PhD, Yerkes National Primate Research Center of Emory University, Candler Professor of Neuropharmacology, School of Medicine, Georgia Research Alliance Scholar and Senior Fellow, Center for Ethics, Emory University. 954 Gatewood Rd NE, Atlanta GA 30322. Tel: 404 727 3274

Author of The Addicted Brain: why we abuse drugs ,alcohol and nicotine.