REM Sleep Disorder Could Be Early Warning Of Parkinson's, Dementia That Develops Decades Later

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Main Category: Parkinson's Disease
Also Included In: Alzheimer's / Dementia;  Neurology / Neuroscience;  Sleep / Sleep Disorders / Insomnia
Article Date: 29 Jul 2010 - 9:00 PDT

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American neurologists and sleep experts suggest in a recent study that rapid eye movement (REM) sleep behavior disorder could be an early sign of Parkinson's disease or dementia that develops up to 50 years later.

You can read how neurologist and sleep specialist Dr Bradley F. Boeve and colleagues from the Mayo Clinic College of Medicine, Rochester, Minnesota arrived at their findings in an online before print issue of a paper published in the journal Neurology on 28 July.

Rapid eye movement (REM) typically happens several times during a night's sleep, and normally during REM nearly every muscle is paralyzed and our bodies lie still.

But in REM sleep behavior disorder the paralysis is either incomplete or absent altogether, allowing the sleeper to "act out" his or her dreams.

"Usually, they're nightmarish, violent dreams with the person being chased or attacked by something or someone," comments Boeve in a Mayo Clinic web page about the disorder. He says people experiencing the disorder try to defend themselves, or engage in the fight they are dreaming about, and punch and kick while asleep.

This can lead to injury as they fall or jump out of bed, hitting the bedpost or furniture, and sometimes bed partners can get hurt too.

The disorder is much more common in men than women and usually starts in middle age or later, although younger people can have it too.

For their study, Boeve and colleagues searched patient records held at the Mayo Clinic and identified 27 patients registered between 2002 to 2006 who experienced rapid eye movement (REM) sleep behavior disorder between for at least 15 years before developing one of three neurological conditions: Parkinson's disease, dementia with Lewy bodies or multiple system atrophy (a disorder with symptoms similar to Parkinson's).

All the patients were examined by specialists in sleep medicine to confirm REM sleep behavior disorder and neurologists to confirm the later disease symptoms.

13 of the patients developed dementia, 13 developed Parkinson's and one developed multiple system atrophy.

The researchers found that the median interval between onset of REM sleep behavior disorder and the neurological disease symptoms was 25 years and ranged up to 50 years.

They wrote that:

"At most recent follow-up, 63% of patients progressed to develop dementia [Parkinson's disease or dementia with Lewy bodies]. Concomitant autonomic dysfunction was confirmed in 74% of all patients."

Boeve, who is also a member of the American Academy of Neurology, told the press that:

"Our findings suggest that in some patients, conditions such as Parkinson's disease or dementia with Lewy bodies have a very long span of activity within the brain and they also may have a long period of time where other symptoms aren't apparent."

"More research is needed on this possible link so that scientists may be able to develop therapies that would slow down or stop the progression of these disorders years before the symptoms of Parkinson's disease or dementia appear," he added.

Scientists can't say how many people who experience REM sleep behavior disorder will go on to develop neurological diseases like Parkinson's or dementia.

An editorial comment in the same issue of the journal pointed out there is no evidence that people who experience narcolepsy (eg feeling extremely fatigued and falling asleep unexpectedly several times a day) with or without REM sleep behavior disorder, will later develop neurdegenerative disease.

"REM sleep behavior disorder preceding other aspects of synucleinopathies by up to half a century."
D. O. Claassen, K. A. Josephs, J. E. Ahlskog, M. H. Silber, M. Tippmann-Peikert, and B. F. Boeve.
Neurology, Published online before print 28 July 2010.
DOI:10.1212/WNL.0b013e3181ec7fac

Additional source: American Academy of Neurology, Mayo Clinic.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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