Sleep-wake changes in the premotor stage of Parkinson disease.

Longitudinal studies in Parkinson disease (PD) have shown that the prevalence of sleep disorders increases with advanced disease. However, two sleep disorders, namely excessive daytime sleepiness (EDS) and REM sleep behavior disorder (RBD) have been described to antedate the development of the classical motor signs and symptoms of PD. One epidemiological study from the Honolulu-Asia Aging Study showed that aging men who reported "being sleepy most of the daily" had a threefold excess risk for developing PD after a seven-year follow-up. The origin and nature of EDS were not investigated. This study needs to be replicated. More robust data exist regarding RBD as the first manifestation of PD. RBD subjects commonly develop parkinsonism and cognitive impairment with time. Patients with the idiopathic form of RBD with decreased striatal dopamine transporters imaging, substantia nigra hyperechogenicity and hyposmia have an increased short-term risk for developing the classical motor, dysautonomic and cognitive symptoms of a synucleinopathy. Patients with idiopathic RBD, particularly those with abnormal subclinical features seen in the synucleinopathies such as decreased striatal dopamine transporters uptake, are the ideal population to be tested with disease-modifying agents in order to stop or slow down neurodegeneration in the brain.