Doctors at the Mayo Clinic are scrutinizing Parkinson’s disease patients receiving a popular drug therapy, after at least 25 patients who received the treatment became compulsive gamblers.
In a report yesterday in Archives of Neurology, Mayo researchers described 11 Parkinson’s patients who developed “pathological gambling behavior” after treatment with dopamine agonist therapy, a medication that controls movement problems caused by Parkinson’s.
“Those numbers are continuing to grow. We have since identified 14 other Parkinson’s patients [on dopamine agonist therapy] with the same pathological gambling behavior,” Dr. M. Leann Dodd, a Mayo Clinic psychiatrist and lead author of the report, said yesterday.
The Archives report included a man — who had never gambled before — incurring $200,000 in gambling losses in six months. Another person, who had “occasional minimal losses” before going on dopamine agonist therapy, said his losses become compulsive after the treatment, and cost him up to $1,000 per night.
Dopamine is a brain chemical that plays a central role in the behavioral reward system.
Dr. Dodd said all three commonly prescribed dopamine agonists were linked to pathological gambling in the Mayo Clinic study. But the report said a drug known as pramipexole (trade name: Mirapex) was “disproportionately represented” among Parkinson’s patients who became pathological gamblers, accounting for more than 80 percent.
Scientists speculate that the drug’s “disproportionate stimulation” of dopamine D3 receptors in the brain might be responsible for pathological gambling in Parkinson’s patients.
“In summary, dopamine agonist drugs appear to be uniquely implicated as a cause of pathological gambling,” the authors concluded.
Boehringer-Ingelheim Pharmaceuticals Inc., manufacturer of Mirapex, denies there is evidence that the drug causes compulsive gambling, but they added an insert mentioning the reports of the side effect.
Joe Neglia, 54, of Millersville, Md., said that when he was on Mirapex, he lost “thousands of dollars” playing slots.
“I stopped taking the drug in August 2003, and 72 hours later, I stopped gambling,” said Mr. Neglia, who was not part of the Mayo Clinic research.
Daniel Kodam, a California lawyer, said he is representing Mr. Neglia and about 200 other Mirapex patients nationwide in a lawsuit against the manufacturer.
“Almost all the plaintiffs said they experienced compulsive gambling after going on the drug, and a few indicated they engaged in excessive sex, eating or shopping” and were not given adequate warnings, Mr. Kodam said.
Doctors at the Mayo Clinic say they are successfully switching patients on dopamine agonists to other drugs if they develop gambling problems. In Maryland, Mr. Neglia said he is now taking a treatment called Sinemet.
“It works, but I have to take more to compensate,” he said.
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