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the gateway drug

Drugs used to treat Parkinson's can cause uncontrollable urges, addictions in patients

Researchers say that drugs called dopamine agonists, which are often prescribed to people with Parkinson's disease, are linked to complete shifts in behavior in patients. Some patients have reported becoming compulsive gamblers, out-of-control shoppers, or sex addicts.

The team, made up of researchers from the Institute for Safe Medicine Practices, Harvard University, and the University of Ottawa, scoured 2.7 million reports of drug reactions from 2003 to 2012, stored in an FDA database. They found 1,580 adverse effects involving impulse control disorders, NPR reports, and 710 reports were linked to dopamine receptor agonist drugs.

The researchers say they want to bring awareness to doctors about the risks of these drugs by getting black-box warnings placed on packaging. In addition to Parkinson's, dopamine agonists can be used to treat restless leg syndrome and the hormonal condition hyperprolactinemia. Some drugs, like Requip, already warn doctors in the instructions that the medication may cause a patient to "experience compulsive behaviors and other intense urges."

Usually, the behavior goes away once the drug stopped; that's what happened to one 52-year-old man whose case was reported by the Mayo Clinic, but not before he lost $100,000 through gambling and became addicted to porn. While patients are usually quick to tell their doctors when a new drug makes them feel nauseated or light-headed, they aren't as likely to jump up and say they are now addicted to gambling. But such compulsive behaviors "are more important than 99 percent of the other side effects that are listed," neurologist Howard Weiss tells NPR, and it's extremely important for doctors and patients to discuss them.

The findings were published Monday online by JAMA Internal Medicine.