Mayo Clinic Studies Find REM Sleep Behavior Disorder is Associated with Other Features of Neurodegenerative Disorders

Tuesday, April 15, 2008

Three new Mayo Clinic studies find that REM (rapid eye movement) sleep behavior disorder is associated with anxiety, apathy, lower scores in attention and executive functioning, as well as symptoms of Parkinson's disease. The findings will be presented at the American Academy of Neurology Annual Meeting in Chicago on April 15.

People who have REM sleep behavior disorder (RBD) appear to act out their dreams, which often are unpleasant and violent. Acting out is caused by a loss of normal muscle paralysis in REM sleep, the stage of sleep when dreaming occurs. A relatively uncommon condition, RBD is estimated to affect approximately 0.5 percent of the population, but occurs most frequently in older males.

"Previous studies have shown that some patients with RBD subsequently develop dementia and/or parkinsonism, which typically reflects a neurodegenerative disorder such as Lewy body dementia or Parkinson's disease," says Bradley Boeve, M.D., an author of these studies and a neurologist at Mayo Clinic. "Our knowledge on the RBD-neurodegenerative disease association is largely based on studies focused on single patients, or small groups of patients, with RBD. There are very few studies that have been carried out on RBD on a large scale. Plus, we currently aren't able to identify which patients with RBD will later develop other features of a neurodegenerative disease and which patients with RBD will not. We therefore sought to study RBD and other features commonly associated with Lewy body dementia and Parkinson's disease in a large population-based study."

Dr. Boeve and a team of Mayo Clinic physicians set out to determine whether cognitively-normal individuals with RBD have other features commonly associated with Lewy body dementia and Parkinson's disease. They identified 765 individuals, ages 70 to 89, who underwent a battery of scales and tests. Using the Mayo sleep questionnaire, a validated screening measure for RBD, researchers determined that 8 percent of these individuals had probable RBD. Twenty-one percent with probable RBD had anxiety and 11.5 percent had apathy (compared with 8 percent and 4 percent, respectively, for individuals without RBD). Those individuals with RBD had significantly lower scores on neuropsychological measures of attention and executive functioning, such as concentration, decision making, and higher-order problem solving. Additionally, researchers found that 1.8 percent of the individuals had both RBD and parkinsonism.

"There is currently no treatment to delay the onset or prevent dementia or parkinsonism in patients with RBD who are destined to develop these neurologic problems in the future," says Dr. Boeve. "Our ultimate goal is to use therapies that would delay the onset or prevent these problems from ever developing in patients who have a form of RBD that reflects an evolving neurodegenerative disease. However, much more research is needed to get to that point."

Dr. Boeve and his team will continue to study this group of patients to better understand how RBD is associated with neurodegenerative disease. Other members of the Mayo Clinic research team included Jennifer Molano, M.D., Ebru Mihci, M.D., Rosebud Roberts, M.B.Ch.B., Yonas Geda, M.D., David Knopman, M.D., Eric Tangalos, M.D., Glenn Smith, Ph.D., Robert Ivnik, Ph.D., Ruth Cha, V. Shane Pankratz, Ph.D., Michael Silber, M.B.Ch.B., Tanis Ferman, Ph.D., and Ronald Petersen, M.D., Ph.D.

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