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Can an old drug learn new tricks?

New research suggests that a popular diabetes medicine may have a previously unknown ability to treat Parkinson’s disease.

Unlike other Parkinson’s treatments, this one might actually affect the course of the disease itself, instead of merely relieving symptoms.

The drug exenatide, sold under the brand name Byetta, is approved by the U.S. Food and Drug Administration (FDA) to help people with type 2 diabetes control blood sugar. Although the drug is a long way from earning FDA approval for treating Parkinson’s disease, researchers are excited about the possibility.

"With existing treatments, we can relieve most of the symptoms [of Parkinson's] for some years, but the disease continues to worsen," said Tom Foltynie, senior author of the study, in a news release. He’s a professor at University College London where the study was conducted. "This is the strongest evidence we have so far that a drug could do more than provide symptom relief for Parkinson's disease," he explained.

How the study was conducted

Out of 60 volunteers with Parkinson’s disease, some were injected with exenatide once a week while others were given a placebo. They were evaluated after 48 weeks when the treatments ended and again 12 weeks later to see if there were lasting effects. At both points, the people who got exenatide showed small but significant improvements in motor function, while members of the placebo group had declining motor skills.

Exenatide users didn’t notice the improvements during the study because they also kept taking their usual Parkinson’s medication. When they were temporarily taken off all medication to measure results, tests showed that the disease’s progress had slowed.

About Parkinson’s

Parkinson’s disease is a neurological condition that strikes more than 50,000 Americans every year. Symptoms include constant shaking in hands, limbs, or elsewhere, muscle stiffness, and difficulty walking and talking. The disease develops gradually, most often beginning around age 60. There’s no cure, but treatments help control the symptoms.

What the future holds

Though the small study’s results are encouraging, more research is needed to confirm its findings and determine whether exenatide could slow Parkinson’s disease permanently.

If you already take exenatide (Byetta) for diabetes, you might wonder whether it could help prevent you from developing Parkinson’s disease. No one knows. The current study did not seek to answer that, but the question should be of interest to researchers in the future.