"It's further evidence that the increased frequency (of addictions) in Parkinson's patients is due to the treatments themselves not the illness," said Dr. Daniel Weintraub, the study's lead author from the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.

In 2010, Weintraub found that people who took certain Parkinson's medications were three times as likely to have impulse control problems such as gambling, binge eating, shopping sprees and compulsive sexual behaviors (see Reuters article of May 10, 2010 here: reut.rs/UU9GK9).

So-called dopamine agonists, such as GlaxoSmithKline's Requip or ropinirole or Boehringer Ingelheim's Mirapex or pramipexole, are meant to stimulate parts of the brain in people with Parkinson's to improve movement, stiffness and tremors.

Patients with the incurable disease have difficulties with movement, muscle control and balance and can eventually become paralyzed and die. The U.S. National Institutes of Health says 500,000 people are thought to have Parkinson's disease, and about 50,000 new cases are reported every year.

For the new study, Weintraub and his colleagues, who published their findings in the journal Neurology, surveyed 168 people with untreated Parkinson's disease and 143 people without the condition.

Each person was asked about - among other things - compulsive gambling, shopping, sexual behaviors and eating.

Overall, there were no significant differences between the two groups when it came to any of the compulsive behaviors.

About 1 percent of participants in each group reported a gambling problem, between 2 and 3 percent a shopping addiction and between 3.5 percent and 4 percent a sexual behavior addiction.

In each group, about 20 percent of participants had an impulse control problem.

"This study seems to support that fact it's related to the medication," said Dr. Anhar Hassan, who was not involved with the new study but researches movement disorders.

According to Hassan, from the Mayo Clinic in Rochester, Minnesota, the link between the Parkinson's drugs and the addictions was first discovered between 2003 and 2004. Since then, she said, it's become a well-known side effect amongst Parkinson's patients.

"It's our routine practice to warn patients that this is a potential side effect when we're starting them on these medications," she said, adding that they screen for the behaviors during checkups.

"There is a potential for these to be quite devastating," she said.

SOURCE: bit.ly/UU7Uc4 Neurology, online January 7, 2013.

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