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REM sleep behaviour disorder is an early marker of neurodegenerative diseases

June 29, 2006

The front page of the July 2006 issue of The Lancet Neurology, the journal with the highest international impact, contains a work that shows the relationship between disorders during REM sleep and future neurodegenerative pathologies. This study has been conducted by a Hospital Clinic group led by Dr. Alex Iranzo. This study is a good example of the fact that a correct diagnosis of sleep disorders by a specialist group can achieve a high relevancy. This diagnosis is possible in the Hospital Clínic thanks to the Multidisciplinary Unit of Sleep Disorders, which is in operation since May 2003, and which consists in 17 specialists from five areas, namely, neurology, psychiatry, psychology, otorhinolaryngology, and pulmonology. This organisation permits a multidisciplinary approach with high resolution tests, department clinical protocols and sessions, with a clear optimisation of resources. The most frequent pathologies treated in this unit are sleep apnoea, snoring, REM sleep behaviour disorders, narcolepsy, night epilepsy or hypersomnia. Only last year, 3,809 visits, 1,819 sleep tests and 40 surgical interventions were made in the unit.

As well as clinical and teaching areas, this unit has high research activity as shown by the study explained below. This work has been led by Dr. Alex Iranzo, member of the Unit of Neurology of Hospital Clínic and of the Functional Studies of the Nervous System Group of the Institut d'Investigacions Biomîdiques August Pi i Sunyer (IDIBAPS). Not only The Lancet Neurology published the work, but also it dedicates the front page to the article, and a reflection by Canadian neurologists Dr. Ronald Postuma (Department of Neurology of the Montreal General Hospital de Québec) and Dr. Jacques Montplaisir (Centre D'Etude du Sommeil in the Hospital du Sacre-Coeur de Montreal).

This article is based in a descriptive study conducted since 1991 in which 44 patients from the Unit of Sleep Disorder of the Hospital Clínic were assessed. Given the low incidence of this disorder, the sample of patients studied by this Catalan group is the highest until today. All these patients presented idiopathic REM sleep behaviour disorder. These patients, usually over 60 years, suffer from unpleasant dreams and express uneasiness by screaming, crying, kicking, punching and even falling from their beds.

According to the results of this study, 20 of these patients (45%), after being correctly diagnosed in the centre and followed up during five years, developed a neurodegenerative disease. This incidence is much higher than what is expected in the general population of the same age and gender. Therefore, scientists drew the conclusion that this disorder permits the early detection of neurodegenerative diseases such as Parkinson's disease, Lewy body dementia, multiple system atrophy or mild cognitive impairment. Furthermore, the fact that the twenty patients who developed a neurodegenerative disease were those who had suffered from REM sleep behaviour disorder for the longest time, suggests that this incidence could be superior in the future.

The importance of these results lie firstly in the future possibility of administrating neuroprotective drugs to patients with the REM sleep behaviour disorder who have still not developed a degenerative disease. Furthermore, the monitoring of these patients will permit an early administration of palliative drugs, which are already available. Toward this end, the Ministry of Health has awarded this group with a FIS award named "Prognostic markers of the development of a neurodegenerative disease in patients affected with REM sleep behaviour disorder".

Institut D'Investigacions Biomîdiques August Pi i Sunyer