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Compulsive Behaviors in Parkinsonís Disease: Whoís At Risk?

Scientists funded in part by the Parkinson’s Disease Foundation have identified risk factors for impulse control disorders (ICDs), troubling side effects which are associated with medications used to treat the motor symptoms of Parkinson’s disease (PD). Their research, published in the January 2, 2013 issue of Movement Disorders, may help doctors recognize or prevent ICDs in people living with PD.

People with Parkinson’s disease who take certain medications may develop ICDs, which include behaviors such as compulsive eating, gambling, shopping or sexual activity. Among these medications are a class called dopamine agonists, which include bromocriptine (Parlodel®), pramipexole (Mirapex®), pramipexole dihydrochloride extended-release (Mirapex ER®), ropinirole (Requip®), ropinirole extended-release tablets (Requip® XL™), and rotigotine transdermal system (Neupro®).

Dopamine agonists help to replace lost dopamine and are often prescribed early in the disease because they have fewer motor side effects than the standard treatment for PD, levodopa. These drugs can affect several areas of the brain, not only the specific area of the brain affected by PD.  Recent studies suggest that dopamine agonists can cause serious nonmotor complications, such as ICDs.

Researchers at Weill Cornell Medical Center, led by Melissa Nirenberg, M.D., Ph.D., (now on faculty at NYU Langone Medical Center) investigated why some people who take dopamine agonists develop ICDs, while others do not. For a period of four years, they studied 46 people with PD who were taking dopamine agonists and had no prior history of ICDs. They observed whether people developed an ICD during this time, and also recorded their caffeine use, cigarette smoking and dopamine agonist dosage.

Results

  • 18 of the 46 volunteers who were taking dopamine agonists (39.1 percent) newly developed one or more ICDs: 16 developed compulsive eating, one experienced hypersexuality, five developed compulsive shopping or buying, and one reported compulsive gambling.
  • 12 of the 18 people who developed ICDs also experienced punding behaviors, which are defined as the repetitive performance of tasks such as sorting, organizing or using the Internet.
  • The onset of ICDs ranged from three months to almost 10 years after beginning dopamine agonist therapy.
  • At the beginning of the four-year study, the people who ultimately developed an ICD were more likely to have experienced motor complications than those who didn’t develop an ICD (61.1 percent versus 25 percent).
  • People who used caffeine, had smoked cigarettes during their lifetime, and had higher maximum doses of dopamine agonists were more likely to develop an ICD.
  • 13 of the 18 people who developed ICDs overcame the disorders by discontinuing or reducing dopamine agonist therapy.

What Does It Mean?

Dopamine agonists have an important role in the treatment of people with PD. However, the potential risk for ICDs is a major concern for people treated with dopamine agonists. ICDs can have serious financial, medical, legal and social consequences in the lives of those who suffer from them. If only doctors could predict who is at risk for ICDs, they would be able to avoid using these medications in those at risk, or at least use them more cautiously, assessing frequently for this potential side effect.

This study identified risk factors, including smoking, caffeine use, and a high maximum dose, that may make people more susceptible to an ICD when taking a dopamine agonist medication.

The study, the first to follow dopamine agonists usage over time, provides further evidence that ICDs are a relatively common side effect of dopamine agonists. Previous studies estimated 17 percent prevalence, while in this study ICDs occurred in 39.1 percent of the study group.

The researchers do not know why certain lifestyle factors increase ICD risk, but it is possible that people with an underlying susceptibility to addictive behaviors such as smoking or caffeine use may also be more susceptible to ICDs. Another possibility is that the addictive substances themselves predispose people to developing ICDs. Ironically, both caffeine use and cigarette smoking have been associated with a lower risk of developing PD. Further research is needed to dissect the complex relationships among lifestyle factors, PD development and ICDs.

Tapering or stopping dopamine agonists therapy (slowly and under the care of a doctor) can ease and stop ICDs completely. Unfortunately, however, some people are unable to discontinue the drugs because their motor symptoms worsen, or because they develop dopamine agonist withdrawal syndrome (DAWS). DAWS causes severe withdrawal symptoms similar to those experienced by people withdrawing from drugs like cocaine. Therefore, it is important for doctors to prevent ICDs whenever possible. Doctors may want to reconsider placing people with risk factors on dopamine agonist therapy, or at least reduce their maximum dose of the medication.

Some people with an ICD do not recognize that they suffer from the disorder. Therefore, it’s important for care partners, friends, and family members to monitor compulsive behaviors in people with PD and bring them to the attention of doctors. Because some people in this study developed an ICD years after starting a dopamine agonist medication, such monitoring must occur over the long term, throughout the course of dopamine agonist therapy.

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Source Date: Jan 14 2013