Health - Reuters
Dopamine May Be Key to Kicking the Habit: Study
Wed Sep 4, 5:44 PM ET
By Keith Mulvihill
NEW YORK (Reuters Health) - A drug that blocks a chemical critical to the brain's "reward" system appears to aggravate cigarette cravings, while a drug that boosts levels of the chemical, dopamine, may weaken the urge to puff, according to the results of a study of heavy smokers.
The findings suggest that drugs that mimic dopamine in the brain may help smokers give up the habit, explained lead author Dr. Nicholas H. Caskey of the Veterans Affairs Greater Los Angeles Healthcare System in California.
Several animal studies have found that nicotine boosts levels of dopamine in certain areas of the brain associated with reward, Caskey noted in an interview with Reuters Health. But little research has looked at the role of dopamine in human smoking behavior.
In the current investigation, Caskey and colleagues describe what happened when they gave heavy smokers one dose of the drug bromocriptine, which mimics dopamine's effects in the brain. One week later the same group of smokers took a different drug, haloperidol, which impedes dopamine activity in the brain.
During each session, the researchers monitored various aspects of the participants' smoking behavior for the 5 hours after they took the drug. All of the smokers had previously reported smoking 15 or more cigarettes each day. The findings are published in the September issue of the journal Nicotine and Tobacco Research.
When the smokers took bromocriptine they smoked fewer cigarettes, took fewer puffs and smoked more slowly compared to when they took haloperidol, Caskey told Reuters Health.
The findings suggest, Caskey noted, that dopamine plays a role in reinforcing smoking behavior.
"Either bromocriptine or another drug may have the potential to be a smoking cessation treatment," Caskey said. "But this study is a long way off from saying that bromocriptine is that drug."
He said a larger clinical trial must be conducted to confirm the findings.
Bromocriptine has been approved for the treatment of Parkinson's disease ( news - web sites), as an anti-tumor medication, and for women who have problems with their menstrual cycle.
SOURCE: Nicotine and Tobacco Research 2002 September.
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