Researchers have discovered that three-quarters of patients with idiopathic rapid eye movement (REM) sleep disorder behavior have a high risk of suffering from neurodegenerative diseases such as Parkinson's and dementia, Seoul National University Hospital said Thursday.
|Professor Jung Ki-young|
The researchers concluded so after a long-term follow-up study on idiopathic REM sleep disorder patients diagnosed by neurologists at 24 centers in 11 countries.
Professor Jung Ki-young of the department of neurology at the hospital was the only co-researcher from Asia to participate in the study, conducted mainly by medical institutions in North America and Europe.
REM sleep is a single phase of sleep distinguishable by a random or rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly. During REM sleep, it is normal for the muscles to relax and not move. However, muscles for patients with idiopathic REM sleep disorder are tense and not relaxed, which makes patients reproduce their dream behavior in real life.
Such are the reasons why trauma is frequent, while the prevalence rate of the total population suffering from idiopathic REM sleep behavior disorder is about 0.38 to 0.5 percent and 2.01 percent in the elderly population.
The researchers followed up with 1,280 patients with idiopathic REM sleep disorders after confirming their symptoms through sleep polyp tests.
The mean age of the patients was 66.3 years and the mean follow-up period was 4.6 years, while the most extended follow-up case was 19 years.
The researchers estimated the risk of dementia and Parkinson’s disease by assessing the Kaplan-Meier and Cox proportional hazard model.
As a result, 6.3 percent of patients with idiopathic REM sleep disorder showed neurodegenerative disease symptoms annually, while 73.5 percent of patients with idiopathic REM sleep behavior later showed signs of neurodegenerative diseases after 12 years.
The risk factors for neurodegenerative diseases were motor abnormalities, olfactory abnormalities, mild cognitive impairment, erectile dysfunction, motor symptoms, dopaminergic imaging abnormalities, color vision abnormalities, constipation, loss of REM sleep nystagmus, and age.
Idiopathic REM sleep behavior disorder is considered to be a pre-existing stage of neurodegenerative diseases such as Parkinson's disease, rheumatic dementia, and multiple system atrophy. Therefore, accurate diagnosis of the rate of progression to neurodegenerative disease and the predictor of progression of neurodegenerative diseases can provide an opportunity for neuroprotection.
Like idiopathic neurodegenerative disorders, there is no cure for early symptoms of idiopathic REM sleep disorders as there are no drugs that can cure them.
However, as early treatment of other neuro-degenerative diseases can help slow the progression, the researchers presume that it will have similar effects for idiopathic REM sleep behavior disorder.
Therefore, predicting patients, who are at high risk for developing neurodegenerative diseases, can lead to a much-improved quality of life for the patients.
“Although it has been well known that idiopathic REM sleep behavior disorder progresses to neuro-degenerative disease, this is the first study to confirm the results through a multicenter long-term follow-up,” Professor Jung said. “Especially, the fact that Korean patients show the same response as international patients is a significant finding ."
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