When most people fall into rapid eye movement (REM) sleep -- where the most vivid dreaming occurs -- the brain shuts down muscle control. This natural paralysis prevents people from physically acting out their sleep.
But for some, muscles fail to relax, causing them to kick and thrash about in their sleep. That condition is called REM sleep behavior disorder (RBD) and can cause physical injury to both the person with RBD and their bed partners. But it holds an even greater threat.
New research confirms that RBD is linked to a higher risk of Lewy body dementia and Parkinson's disease.
Researchers at McGill University in Montreal followed 93 people who were diagnosed with RBD, between 1989 and 2006. Of the 93 participants, 26 of them eventually developed neurodegenerative diseases, including 14 with Parkinson's disease and seven with Lewy body dementia. Four others were diagnosed with Alzheimer's disease, but researchers suspected Lewy body dementia was the proper diagnosis. One person developed a lesser known condition called multiple system atrophy.
The average risk of developing a neurological condition within five years of being diagnosed with RBD was 18 percent, and for those followed for 10 years the risk increased to 41 percent. By 12 years, the risk exceeded 50 percent. By comparison, the risk faced by the general population of developing Parkinson's or Lewy body dementia is in the low single digits.
Read the full story in Science News.