Prescription For an Obsession?

Wayne Kanuch of Texas says when he began taking Mirapex for Parkinson's disease, he became a compulsive gambler. He plans to sue the drugmaker.
Wayne Kanuch of Texas says when he began taking Mirapex for Parkinson's disease, he became a compulsive gambler. He plans to sue the drugmaker. (By Michael Stravato For The Washington Post)

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By Shankar Vedantam
Washington Post Staff Writer
Sunday, March 19, 2006

When Wayne Kanuch received a diagnosis of Parkinson's disease in 1993, the last thing he imagined was that the drug prescribed to treat his illness would turn him into a compulsive gambler and put his libido into overdrive.

Kanuch's marriage ended in divorce, partly as a result of the sexual pressures he placed on his wife, and he began losing fortunes at the racetrack. He was fired from his job at Chevron for trolling for dates on the Internet while at work, and he quickly went bankrupt.

"I contemplated suicide a couple of times," he said in an interview last week. "Everyone was blaming me, and I was looking at the mirror and blaming myself and asking why I could not stop."

New evidence unearthed by scientists at the Food and Drug Administration, Duke University and other centers suggest the reason Kanuch could not stop is that the drug being used to treat Parkinson's boosted the level of dopamine in his brain. Researchers are looking into the possibility that dopamine, which is associated with a host of addictive behaviors, may turn some Parkinson's patients into obsessive pleasure seekers.

Now, some patients are suing the manufacturers of these drugs to recover the money they lost gambling, on the grounds that the companies did not do enough to warn about these risks. Kanuch has not yet sued but plans to do so.

So far, there is no definitive evidence on the connection between dopamine enhancers, known as agonists, and compulsive gambling. The behavioral anomalies, though dramatic, are probably rare among the thousands of Parkinson's sufferers who take the drugs. There have been no controlled studies looking into the possible link.

Drug manufacturers say anecdotal reports from patients such as Kanuch do not constitute scientific evidence, but they say they have updated warning labels anyway. Valeant Pharmaceuticals, which sells Permax, a dopamine agonist, said the matter is under litigation but it has told physicians: "As with other dopamine agonists, compulsive self-rewarding behavior (e.g., pathologic gambling) and libido increase have been reported in patients."

Boehringer Ingelheim, which makes Mirapex, another dopamine agonist, said it has toughened its warning label but said that company officials are still exploring the connection. Eli Lilly & Co, which used to sell Permax, said there is no scientific consensus on the issue and suggested that gambling problems may be linked to the increased accessibility of legalized gambling.

Still, a recent analysis headed by FDA scientist Ana Szarfman found a strong association between pathological gambling and dopamine agonists. The statistics from a federal adverse-events database are not conclusive, but FDA officials regularly mine the data to spot red flags.

"There is decent biochemical plausibility that chemical changes can lead to impulsivity and acts like pathologic gambling," said Duke University psychiatrist P. Murali Doraiswamy, co-author of the analysis, published in Archives of Neurology.

"It is certainly plausible that gambling can be a side effect of a drug that excessively stimulates limbic-system dopamine," Doraiswamy said.

The notion that brain chemicals play a powerful -- but hidden -- role in human behavior is at odds with American convictions about free will and choice. Kanuch and other patients said they spent years believing they were responsible for their actions, only to find that the impulse for self-destructive behaviors vanished once they stopped taking a drug.

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© 2006 The Washington Post Company

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