Parkinson's drug can cause compulsive gamblingMar 1, 2006 | www.mayoclinic.com
A Mayo Clinic specialist discusses the link between a Parkinson's drug and compulsive gambling. This rare side effect might help future researchers develop treatments for addiction.
People who had never seriously gambled before suddenly were losing thousands of dollars at casinos sometimes more than $100,000. Men who had been content with once-a-week sex began having sex three and four times a day. Some began to overeat, gaining 50 pounds in just a few months.
What did all these people have in common besides their compulsive behavior? They were all taking a type of medicine, called dopamine agonists, to treat Parkinson's disease. Most of these people were taking one specific dopamine agonist: pramipexole (Mirapex).
M. Leann Dodd, M.D., a psychiatrist at Mayo Clinic, Rochester, Minn., was the lead author of a recent study that shed light on the surprising link between dopamine agonists and the sudden onset of compulsive behavior. In this interview, she answers a few questions about the topic.
How did this connection come to light?
It started coming up at doctor appointments. Patients or their family members would bring it up. It was mostly gambling, but over half of our patients also manifested other compulsive behaviors, such as hypersexuality or compulsive overeating.
It started out as a curiosity, but then we found case reports that showed there might be some connection between this compulsive behavior and a particular type of medication. When people were tapered off these medications, the compulsive behavior would go away. It was a dramatic resolution of the behavior in many of the cases.
What's special about this drug?
People who have Parkinson's are deficient in a brain chemical called dopamine. Dopamine agonists are a synthetic version of dopamine that bind to dopamine receptors in the brain. Pramipexole binds to one particular type of dopamine receptor the dopamine receptor D3 much more than to other dopamine receptors.
These D3 receptors are highly concentrated in the area of the brain devoted to mood, behavior and rewards. It's exciting to think that future studies may reveal more about how the D3 portion of the brain may be associated with addictive behavior. Ultimately, such studies could lead the way to development of medications that curb addictive behavior in general.
Is pramipexole used for other problems?
Pramipexole is also commonly used to treat restless legs syndrome, but at much lower dosages than those used for Parkinson's disease. A common dosage for restless legs is 0.125 milligrams (mg) a day, while the daily dosage for Parkinson's is more like 4.5 mg.
We haven't yet seen a link between compulsive gambling and pramipexole at these lower dosages. But that's not to say it's not possible.
How often does this side effect occur?
A study of 529 people taking pramipexole for Parkinson's symptoms revealed that 1.5 percent of them had developed compulsive gambling behaviors. Our study evaluated only 11 people, all with Parkinson's, and all of whom had started gambling compulsively while being treated with dopamine agonists.
Studying this select group demonstrated the connection between the drug's strongly selective binding to the D-3 receptors and the development of compulsive gambling. We also measured how long it took for the behaviors to appear after starting on the drug. Most of the people who developed gambling behaviors did so within a month or two. Some took longer.
This drug was approved in 1997. Why are we only seeing this connection now?
Compulsive gambling, hypersexuality and overeating those are things that are not normally associated with Parkinson's medications. And they're pretty embarrassing behaviors. A lot of people are just not going to share these things with their doctors. Even their doctors may not have been aware of this possible connection.
Our key point is to let the public know that they need to tell their doctors when something's amiss. If you start behaving in a way that's out of character for you, you need to talk to your doctor, even if it's embarrassing. We also want to educate physicians about this connection, so they can let their patients know that this side effect is a possibility it is crucial to make this association because these effects are potentially reversible.
Can people get hurt by stopping the drug abruptly?
This is a very good medicine for the treatment of Parkinson's, and people should not just stop taking it on their own. This side effect is very rare. If people think they are experiencing compulsive behavior because of the drug, they should talk to their doctors about it. It might be best to taper off the drug. However, several people in our study abruptly stopped taking the drug, and they didn't experience any worrisome problems.
How is this new information helping people?
One lady, from a family with a modest income, lost $100,000. Her husband and children left her. She remarried and her second husband was about to leave her. She stopped taking the drug and within two weeks the gambling compulsion disappeared.
In a few tragic cases, people have lost their financial security and their relationships. My e-mail box has been flooded with people telling their stories. One man said his wife woke him up, crying, with a newspaper article about this study in her hand. She's had a gambling addiction for two years and now they're hopeful that they've found a possible answer.