Study ties gambling to Parkinson's drug

One American with Parkinson's disease went from being an occasional gambler to racking up losses of more than $100,000. But within a month of discontinuing one of his medications, he stopped betting and his relieved wife told his doctor, "I have my old husband back."

A patient with no history of gambling became so obsessed that he lost more than $200,000 in just six months. When he curbed a drug, his habit faded.

Another man turned into a compulsive gambler who stayed at casinos for days on end and was "unable to pull myself away from the tables." And while on the drugs, the Parkinson's sufferers became obsessed with sex -- one went from having sex once a week to four times a day. Two ate compulsively and one drank more.

The dramatic behavioural changes are outlined in a study published in yesterday's on-line edition of the journal Archives of Neurology. Like previous papers, the research concludes that medications known as dopamine agonists -- especially Miraprex -- trigger pathological gambling.

"It's very striking, this temporal relationship between the initiation of the drug and then the beginning of the behaviour, and then the discontinuation of the drug and the discontinuation of the behaviour," Leann Dodd, a psychiatrist at the Mayo Clinic who led the analysis, said in an interview. "It's suspect, that's for sure."

This year, an Ontario man with Parkinson's launched a class-action lawsuit after losing $100,000 gambling while taking Miraprex, which is the trade name for pramipexole.

Dr. Dodd stressed that a very small number of patients on the class of drugs become compulsive gamblers -- one study found the behaviour in 1.5 per cent of people taking Miraprex -- and that the side effect can be reversed. One of the patients said discontinuing the medication was "like a light switch being turned off."

The Mayo Clinic study examined the cases of 11 patients who reported problem gambling after taking dopamine agonists, that mimic the effect of dopamine, a brain chemical that allows the body to move smoothly and be co-ordinated. Nine patients took Miraprex and the other two took Ropinirole.

Of the 11 people, seven became pathological gamblers within one to three months of reaching a certain level of medication. The other four reported compulsive gambling between 12 and 30 months after beginning the therapy. And six of the patients, the study says, also developed other behavioural changes, including compulsive eating, drinking more, higher spending, and increased interest in pornography, extramarital affairs or a higher libido "bothersome to the spouse."

Eight individuals' pathological gambling was resolved when the dopamine agonist was suspended or decreased, the study says. Follow-up information was not available in the remaining three cases.

Earlier this year, Boehringer Ingelheim (Canada) Ltd. asked Health Canada to change Miraprex's patient insert and product monograph to include warnings that it may cause compulsive gambling or changes in sexual desire.