Edward Nunes, MD

In this brief podcast, Dr Edward Nunes discusses the latest evidence from research studies on stimulant and cocaine dependence. Dr Nunes is Professor at Columbia University Medical Center Department of Psychiatry, in New York.

Along with presenters Andrew Saxon, MD, University of Washington; Theresa Winhusen, PhD, University of Cincinnati College of Medicine; and Madhukar Trivedi, MD, University of Texas Medical Center, Dr Edward Nunes will chair a symposium at the AAAP annual meeting titled "Cocaine and Stimulant Dependence: New Strategies for an Old Problem."

The symposium will cover some of the latest evidence on cocaine dependence, which is often difficult to treat. So far, there have been no medications that have clearly been effective for cocaine dependence, a frustrating fact in the field of addiction medicine. Tobacco dependence, opioid dependence, alcohol dependence-each has effective medications. Cocaine dependence does not yet have any effective medications. The National Institute of Drug Abuse and other agencies have been funding research to try to find medications.

This session will present some different studies that have been done very recently. One such study is of a combination of naltrexone and buprenorphine for treatment of cocaine dependence. The reason it is thought it might work is because buprenorphine is a kappa-opioid receptor antagonist and naltrexone is also an a kappa-opioid receptor antagonist. Naltrexone has the advantage blocking the other effects of buprenorphine. Because buprenorphine is an opiate, you do not want to give it to patients who are not opioid-dependent because you would risk making them opioid-dependent. Naltrexone gets rid of that because it blocks the new opiate receptor which is the main opiate receptor that produces addiction.

The idea here was to block kappa receptors. There are reasons to think that is important. Chronic cocaine dependence causes up-regulation in kappa receptors in the brain, and kappa receptors inhibit the release of dopamine in the brain and dopamine is important for motivation and energy. Dopamine is also depleted in chronic cocaine dependence. So this is an effort to correct the dopamine dysregulation that occurs in cocaine dependence.

The results are still a secret. We don't know what they are going to be but they will be presented at the meeting and so we will see what comes out of that session. This is what's fun about these up-to-date presentations and research studies because sometimes it's the first time the results are presented in a public forum.

A small pilot study on buspirone, which is an anti-anxiety medication that has been around for a long time for cocaine dependence, will be discussed. Buspirone was well tolerated but the results are inconclusive.

Finally, a study that was done, not on medication, but on exercise for cocaine dependence. Exercise is a compelling idea as a way of helping to treat addiction. There are many people in the field that are actually working with patients day to day who believe out of their experience that exercise is helpful for drug dependence.

For example, one of the residential treatment programs in New York City that [Columbia Psychiatry] collaborates with has a very robust exercise program as part of what they offer to their clients.

There are a number of animal models and animal research studies that have suggested that exercise might be helpful for tobacco dependence, cocaine dependence, and other addictions. One study was directed by Dr Madhukar Trivedi, and he knows the data much better than I do, but I have been a collaborator and I know the data, so I can talk a little bit about it. Patients who were cocaine dependent were randomly assigned either to an exercise condition or to a health education condition.

The exercise condition was pretty rigorous. The patients were asked to run on a treadmill for 30 to 45 minutes, 4 times a week, at 70% to 80% of VO2 max. So it was a fairly vigorous exercise program and it was obviously a pretty big time commitment. Patients were asked over a 6-month period to show up 4 times a week for very nice and knowledgeable exercise instructors . . . it was an attractive, welcoming exercise situation.

The study showed that there was no difference in cocaine outcome unfortunately between the patients assigned to exercise and the patients assigned to control condition. But there is a twist because participation in exercise was associated with less cocaine use so those patients who participated in the exercise used less cocaine over time than those in the control condition and those who did not participate in exercise.

What happened is that those who were assigned to exercise were more likely to drop out of treatment so being assigned to exercise caused more individuals to drop out. My hunch about this is that some people like to exercise inherently, they find it inherently fun and important. Many other individuals do not find it inherently fun, which may explain why being assigned to exercise resulted in a higher dropout rate. It is an intriguing study that indicates more work needs to be done to figure out how to make exercise fun and appealing for everybody and then we will get a better sense of what the impact can be on cocaine and other substance use disorders.

Exercise by the way has been shown to be effective for anxiety and depressive disorders, so for those mood and anxiety disorders, does have good evidence of being effective. In terms of the cocaine study that will be presented, it is an interesting first try and will make for interesting discussion.

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Dr Edward Nunes discusses the latest evidence from research studies on stimulant and cocaine dependence in this podcast.

Edward Nunes, MD

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