Problem Gambling Pill Shows Promise

Clinical trials found nalmefene, used to treat heroin overdoses, reduces urge to gamble

(February 23, 2006) -- A pill to treat compulsive gambling is yielding promising results in clinical trials in the United States.

In the first large study to show positive results, nalmefene, approved by the U.S. Food and Drug Administration for the intravenous treatment of heroine overdoses, is proving successful in curbing the urge to gamble.

In a four-month trial of 207 people in 15 outpatient treatment centres across the U.S., researchers at the University of Minnesota found that almost 60 per cent of the participants taking the drug reported a much improved or very much improved condition.

"What makes this stand out," said psychiatrist Dr. Jon Grant, the principal investigator, "is that it shows us gambling addiction can be treated medically, that it is a medical problem just like diabetes, as opposed to a moral problem."

Called an opiate antagonist, nalmefene targets the brain's system for processing pleasure and receiving rewards, its "reward circuitry," said Grant. The drug blocks the part of the brain that processes pleasure, but only pathological pleasure, not simple pleasures like riding a bicycle. It also interferes with the chemical dopamine, which is released when the brain perceives a reward. The result is that the thrill of gambling isn't as thrilling.

"It is a very important result," agreed Martin Zack, a researcher in the clinical neuroscience section of the Centre for Addiction and Mental Health.

The study confirms the belief that addictive behaviour, including gambling, shopping and sex, is a medical condition, said Zack. He compared it to heart disease, which requires both medical intervention and lifestyle changes.

"There are biological processes involved in everything," he said.

Research over the last five years has shown that reward circuitry responds to compulsive behaviour by recalibrating itself, said Zack. In a particularly interesting study, dopamine in monkeys ignited most strongly when it was possible that they might receive a reward but also possible that they might not. A possible reward combined with uncertainty resulted in a particularly high and sustained level of dopamine.

That scenario is similar to gambling, said Zack, where, along with the possibility of winning, there is the risk of losing. In the most recent findings, MRI scans show that if this elevated level of dopamine continues, the system recalibrates itself, becoming more tolerant and therefore requiring more to feel the same thrill -- like an alcoholic.

The distinction between physical addictions such as alcohol and behavioural addictions such as gambling or even shopping and sex is arbitrary, said Grant.

The neurobiology is the same.

"These are public health issues," he said. "People don't have to keep living in secrecy any more.

"Finally, there is help."

Nalmefene, manufactured by the Finnish company Bio Tie Therapies, which funded the study, could be particularly helpful in the treatment of the growing number of adolescent gamblers who are more impervious to problems and more difficult to keep in therapy, said Grant.

But Zack cautioned that nalmefene is not likely to be a magic pill.

"There is concern in characterizing this as a magic bullet -- all you need to do is pop this pill and you'll get better." Addictions are notoriously difficult to treat, and medications have not proven to be very effective in the past, he said.

The most successful treatment has been a combination of medication and psycho-social therapy -- counselling to change the way a person thinks and behaves.

In the case of nalmefene, it could offer an opening for new ways of thinking and behaving to take root, said Zack.

Grant is conducting another study of nalmefene with 200 people in 20 sites across the U.S. to confirm the first study.

The second study is expected to be completed by early spring.

If the drug continues to show promise, the FDA could approve it for treatment of compulsive gambling within two years, he said.

Last updated: 02/06

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