Patients with Parkinson's may have increased risk of leg motor restlessness

People with Parkinson's disease may be more likely to have a movement disorder called leg motor restlessness, but not true restless legs syndrome as previous studies have suggested, according to a study published in the November 9, 2011, online issue of Neurology®, the medical journal of the American Academy of Neurology.

Restless legs syndrome is a sleep and movement disorder. People with the disorder have the urge to move their legs to stop uncomfortable sensations. The urge occurs when the person is at rest, in the evening, and is temporarily relieved by movement. In leg motor restlessness, people also have the urge to move their legs, but it is either not worse when they are at rest or during the evening or it does not go away when they move their legs.

Because restless legs syndrome and Parkinson's disease both respond to the drug dopamine, researchers have looked for connections between the two disorders. Some studies have shown that people with Parkinson's disease are more likely also to have restless legs syndrome than people who don't have Parkinson's disease. But those studies have looked at people with advanced cases of Parkinson's who have taken dopamine drugs for many years.

The current study is the first to look at the issue in people who were recently diagnosed with Parkinson's disease and have not yet taken any dopamine drugs. The Norwegian study compared 200 people with early Parkinson's disease to 173 people of similar ages who did not have Parkinson's disease.

The study found that restless legs syndrome was not significantly more common in people with Parkinson's disease than it was in those without the disease. But people with Parkinson's were nearly three times more likely to have leg motor restlessness than those without Parkinson's. A total of 26 people with Parkinson's disease and 10 people without the disease had leg motor restlessness.

"This finding could possibly be because people who have not yet taken dopamine for their Parkinson's disease have a dopamine deficiency in their brains, which is similar to when people develop motor restlessness after taking antipsychotic drugs that block dopamine in the brain," said study author Michaela D. Gjerstad, PhD, of Stavanger University Hospital in Norway and a Fellow of the American Academy of Neurology.

John Morgan, MD, PhD, of Georgia Health Sciences University in Augusta, who wrote an editorial regarding the study, said, "Time will tell whether the majority of these people with leg motor restlessness will go on to develop restless legs syndrome, or whether the restlessness improves after they start taking dopamine drugs. Further study of this group of people will be quite interesting."