Dreams are far from sweet: REM sleep behavior disorder could predict dementia, Parkinson's

A bizarre sleep disorder that affects mostly men and colors their dreams with violence and aggression may be a precursor to the development of Parkinson's disease or Lewy body dementias.

Judith Graham writes in the Chicago Tribune about the little known condition called REM sleep behavior disorder, caused by a dysfunction in the part of the brain that suppresses muscle activity during the dream-filled phase of sleep. Men with the disorder typically describe dreams in which they are chased by large insects or animals or threatening people, which requires them to defend themselves. They can become violent with their partners, and often couples take protective action by putting mattresses on the floor or hiding sharp objects.

Doctors don't know why, exactly, but a growing body of research is showing a link between REM sleep behavior disorder and Parkinson's disease and Lewy body dementia in up to 25 to 50 percent of patients. Dr. Carlos Schenck, one of the doctors who first described the disorder, told the Tribune that neurons in adjacent areas of the lower brain stem appear to be involved.

Dr. Bradley Boeve, a professor of neurology at the Mayo Clinic and a leading expert on the condition, has published multiple studies. One in 2007 appeared in Brain: A Journal of Neurology, and said his data "suggest that many patients with 'idiopathic' (REM behavior disorder) are actually exhibiting an early clinical manifestation of an evolving neurodegenerative disorder." The next year, Canadian researchers wrote about the link with Parkinson's disease. In March 2010, a scientist in Paris wrote about the disorder and how it can precede by severel years the development of Lewy body dementia. Korean scientists had similar findings in their research in February 2010.

More about Lewy body dementia.

More on the subject from the American Family Physician.