Markers for synucleinopathy in patients with idiopathic REM sleep behaviour disorder

To test new potentially neuroprotective agents for synucleinopathies, it is important to identify patients at a very early stage of the disease, with as many neurons preserved as possible. In this context, idiopathic REM sleep behaviour disorder (iRBD) may represent a very early, otherwise subclinical synucleinopathy. REM sleep behaviour disorder is a condition where patients lack muscle atonia during rapid eye movement (REM) sleep and show abnormal sleep-related motor behaviour with enactment of dreams in an often violent manner (Schenck et al. 1986 , Boeve 2010).

There is strong evidence that more than 50% of iRBD patients after several years develop a neurodegenerative disease, mainly a synucleinopathy (a Lewy body disease such as e.g. Parkinson’s disease, or multiple system atrophy). A reason for this may be a temporal sequence of α-synuclein pathology, beginning in the caudal brain stem and the olfactory system, and then ascending to the midbrain, forebrain and finally to the cortical structures (Braak et al. 2004). Several potential markers have been investigated to identify iRBD patients  at risk for developing a neurodegenerative disease. Thus, Postuma et al. recently reported that impaired olfaction and colour vision were risk markers for impending neurodegeneration (Postuma et al. 2011). 
In a multidisciplinary collaboration, research in our department focuses on early markers for an impending neurodegeneration in patients with iRBD, e.g. extracerebral synuclein deposits and changes in pain perception.


Marit Otto, Consultant, PhD,