|Professor Receives Grant to Explore Exercise as Help in Overcoming Cocaine Addiction
October 22, 2009
Contact: Bill Giduz
Mark Smith has already conducted experiments demonstrating that exercise can reduce the desire for cocaine. In a series of critically acclaimed experiments over the past three years, this Davidson College Associate Professor of Psychology tested the motivation of rats to push a lever to receive a dose of cocaine. Rats who regularly exercised gave up when they didn't receive a dose after an average of 70 pushes. Those who were denied exercise kept pushing the lever an average of 250 times.
|Associate Professor Mark Smith (l) in his lab with students. (l-r) Sarah Troutman '10 is a lab assistant, Michael Pennock '11 worked with Smith under an HHMI grant last summer, and Liz Pitts '11 is also a current lab assistant.
Smith's next step in testing the beneficial effects of exercise in overcoming cocaine addiction has just been funded by a grant of almost $1 million from the National Institute on Drug Abuse. The funds will support five years of animal studies to more precisely determine the benefits of exercise at various stages in the addictive process. Can it help people avoid beginning drug use? Will it lessen the amount of drugs new users employ? Can it help people kick an existing habit? Can it help reformed users avoid a relapse into addiction? And does exercise cause any physiological changes in the brain that "immunize" a person against drug abuse?
"We'll be looking at exercise as both a preventative and treatment intervention," Smith said.
The grant will allow Smith to hire a full-time research technician, and Davidson College will provide two student assistants each summer. The grant will cover the cost of rats, and various types of existing and newly conceived chambers in which to house and exercise them. A colleague at Wake Forest University, Dr. David Roberts, will consult with Smith in designing and building a new type of chamber that allows rats concurrent access to both a running wheel and self-administration of drugs.
Standard chambers Smith has used to this point give rats access only to either the running wheel or drug self-administration. Smith posits that the new chamber more closely resembles real-world situations. "Addicts generally have the opportunity to choose between taking drugs or exercising. Maybe when our rats are in that situation they'll choose the running wheel and won't want to use cocaine. That's what I'm hoping," he said.
Smith said he believes exercise is effective because its effects on the brain are similar to the effects of cocaine. Both increase concentrations of the neurotransmitter dopamine, which is believed to contribute to the "runner's high" when exercising.
Smith explained that addiction occurs when people use drugs because the substance "hijacks" the neural pathways in the brain that are responsible for human survival behaviors. Drugs provide the same rewarding feelings that humans get from food, water and sex. But drugs are stronger, and much more effective in mimicking these natural rewards than the brain's own chemistry. Over time individuals become more sensitive to the drugs and less sensitive to the natural chemistry, causing them to abandon their social, occupational and family responsibilities in the quest for another high.
Smith, a 1992 graduate of Lenoir-Rhyne College, has taught classes in general psychology, learning, behavioral pharmacology and clinical psychopharmacology at Davidson since 1998. In graduate school at UNC Chapel Hill, he studied the pain relieving properties of opioid analgesics such as heroin, cocaine and Oxycontin. During a sabbatical at Wake Forest University seven years ago he began animal studies with self-administration of cocaine.
He first began looking for a drug that would help people overcome their addiction. While some drugs can help users overcome some forms of addiction, Smith doubts that an anti-cocaine pill will ever be discovered. "For heroin there's methadone, for nicotine there's Chantix, and for alcohol there's naltrexone," he said. "But I think people will need some form of behavioral intervention for continued improvement with cocaine addiction."
Though his experiments will primarily focus on cocaine, later in the project Smith will also examine heroin, which has a similar effect on neural pathways. Everything should be in place to begin the first of six planned experiments on January 1, 2010.
The thoroughly positive nature of exercise as a treatment leads him to the fervent hope that his work supports its beneficial effects. He noted, "As a potential intervention it's free, it's simple to administer, and it's feasible for use in a large population of individuals. The principal side effects are improved cardiovascular health, reductions in depression and anxiety, and improvements in physical appearance. You've got to admit that's an excellent intervention regardless of the disorder!"
In addition to the National Institute on Drug Abuse grant, Smith recently received an additional $50,000 grant from the American Reinvestment and Recovery Act to investigate whether simply socializing can help people overcome addiction. He'll construct a large chamber in which two animals can live together and self-administer drugs simultaneously to determine whether peer contact influences drug use. "What happens if one rat is not given access to cocaine?" Smith said. "Does having an abstaining roommate reduce your own drug intake?"
His quest is both academic and personal. He said, "Three percent of Americans use cocaine at least monthly, and like most Americans I have friends and have known others who struggled with drug addiction at one point in their lives."
Smith recognizes that addiction is a chronic disease, with about half of all users relapsing within a year after treatment. He said, "There are a multitude of both genetic and environmental determinants in drug abuse. As a consequence, you're going to need a large arsenal of interventions to combat the disorder. Better medications will be developed, but I think the best results will occur with behavioral interventions through psychotherapy and regular exercise."
Perhaps Smith could serve as evidence in his own study. He runs about 5 kilometers three or four times per week, and enjoys the runner's high it brings him. He imagines that the effect must be at least as attractive to his experimental rats, who run an average of 10 kilometers per day every day they have access to the wheel.
Though his major study is only now beginning, he has great hopes for its success based on feedback from his previous experiments. In addition to a warm reception in the scientific community, he was gratified to receive several personal testimonials from people who read about it in the popular press.
A former British drug addict sent him an e-mail that read in part, "A couple of years ago I was a regular cocaine user and occasional user of other recreational drugs. I fell into a bit of a hole and it was something I was not proud of, as I had been a very promising athlete when I was younger....However, about 9 months ago I decided to take up running again and I threw all my efforts into training. After a mere few weeks all my energy was being thrown into training and I was not even tempted by any drug on a night out.... Now I am completely addicted to athletics again.... I think your research is hugely important and I think something as simple as encouraging the young or even the addicts into exercise could transform their lives. It is so simple and I am so glad people such as yourself are trying to spread the word and put your energy into such research."
Davidson is a highly selective independent liberal arts college for 1,800 students located 20 minutes north of Charlotte in Davidson, N.C. Since its establishment in 1837 by Presbyterians, the college has graduated 23 Rhodes Scholars and is consistently regarded as one of the top liberal arts colleges in the country. Through The Davidson Trust, the college became the first liberal arts institution in the nation to replace loans with grants in all financial aid packages, giving all students the opportunity to graduate debt-free. Davidson competes in NCAA athletics at the Division I level, and a longstanding Honor Code is central to student life at the college.