CHICAGO Parkinson's drugs can triple the odds that people develop impulse control problems such as gambling, binge eating, shopping sprees and compulsive sexual behaviors, U.S. researchers said on Monday.
The study of more than 3,000 people with Parkinson's disease confirms that so-called dopamine agonists, such as GlaxoSmithKline's Requip or ropinirole or Boehringer Ingelheim's Mirapex or pramipexole, can cause impulse control problems.
And it may mean doctors who prescribe the drugs for other conditions like restless legs syndrome should watch for these symptoms in patients, they said.
"For some time now we've suspected there might be an association between exposure to dopamine agonists and the development of impulse control problems in patients," said Dr. Daniel Weintraub of the University of Pennsylvania and the Philadelphia Veterans Affairs Medical Center, whose study appears in the Archives of Neurology.
Dopamine agonists work by helping the brain make more dopamine, the message-carrying chemical made by brain cells destroyed by Parkinson's. Patients with the incurable disease have difficulties with movement, muscle control and balance and can eventually become paralyzed and die.
Weintraub's team studied 3,090 Parkinson's patients. Nearly all were taking either a dopamine agonist or a levodopa dopamine replacement drug such as Bristol-Myers Squibb's Sinemet.
They found impulse control disorders in 13.6 percent of patients taking a dopamine agonist, including compulsive gambling in 5 percent of patients, compulsive sexual behavior in 3.5 percent of patients, compulsive buying in 5.7 percent and binge-eating in 4.3 percent.
And 4 percent of patients had two or more of these disorders, the team found.
"It confirms that dopamine agonist treatment is associated with one or more impulse control disorders in patients with Parkinson's disease," he said.
Weintraub said there was also an association with the impulsive behaviors in patients taking levodopa, but it was much weaker.
Weintraub said more study is needed to see whether impulse control problems occur at the same rates in people who take dopamine agonists for restless legs syndrome because the drugs are often given at lower doses.
(Editing by Maggie Fox; Editing by Cynthia Osterman)