REM Sleep Behavior Disorder Linked With Parkinson's, Mild Cognitive Impairment: Study

People with REM sleep behavior disorder -- where they act out dreams that occur during the REM stage of sleep -- may be at an increased risk for memory problems and Parkinson's disease, according to a new study.

Researchers from the Mayo Clinic found that people with REM sleep behavior disorder have a doubled risk of developing mild cognitive cognitive impairment or Parkinson's disease, according to the Annals of Neurology study. The increased risk lies in the first four years of being diagnosed with the disorder.

"Understanding that certain patients are at greater risk for MCI or Parkinson's disease will allow for early intervention, which is vital in the case of such disorders that destroy brain cells," study researcher Brad Boeve, M.D., a Mayo Clinic neurologist, said in a statement. "Although we are still searching for effective treatments, our best chance of success is to identify and treat these disorders early, before cell death."

When people are in the REM (rapid eye movement) sleep stage, there is paralysis of the muscles so that people don't act out their dreams. However, when people have REM sleep behavior disorder, this paralysis doesn't occur, so the person is able to actually move their bodies to act out the dreams, according to WebMD. The condition is most common in middle age and elderly people, with men experiencing it more than women.

The Mayo Clinic researchers analyzed more than 600 study participants between the ages of 70 and 89, and found that 34 percent of those diagnosed with "probable REM behavioral disorder" went on to develop Parkinson's or mild cognitive impairment in the four years after their diagnosis of the sleep condition.

Researchers reported that this rate is 2.2 times higher than normal.

"This study is the first to quantify the risk associated with probable RBD in average people, not clinical patients, and it shows that we can predict the onset of some neurodegenerative disorders simply by asking a few critical questions," study researcher Dr. Brendon P. Boot, M.D., a behavioral neurologist, said in the statement. Boot was with Mayo when the study was conducted, but is now with Harvard University.

For more on sleep conditions (including advice and explanation from Dr. Philip Gehrman, PhD, CBSM, clinical director of the Behavioral Sleep Medicine Program at the University of Pennsylvania), click through the slideshow:

7 Sleep Conditions