Ghielmini E Poryazova R Baumann CR Bassetti CL 2013 BACKGROUND We aimed to investigate the differential roles of hypocretin versus dopamine dysfunction versus excessive daytime sleepiness (EDS) in the development of hyposmia. Olfaction in patients with Parkinson disease, restless leg syndrome, narcolepsy with cataplexy, EDS, and healthy controls was compared. METHODS Sixty-six subjects participated in the study: 14 with PD, 13 with NC, 12 with RLS, 8 with EDS, and 20 healthy controls. Olfaction was tested using standardized Sniffin'Sticks test. Sleepiness was assessed using Karolinska, Stanford and Epworth sleepiness scales. RESULTS Olfactory discrimination correlated negatively with subjective momentary sleepiness. A significant deficit in olfaction was found in PD patients with respect to all other groups in all olfactory domains. No significant differences were found between the other groups. CONCLUSION We could not confirm decreased olfaction in patients with NC. Yet the significant correlation between momentary sleepiness and olfactory function suggests that sleepiness is a potential confounding factor in the assessment of olfaction, e.g. in NC. Furthermore, our results confirm that olfaction is impaired in PD, whereas it is normal in RLS. application/pdf https://sonar.ch/global/documents/141495 eng info:eu-repo/semantics/altIdentifier/doi/10.1159/000337449 info:eu-repo/semantics/altIdentifier/pmid/23146877 info:eu-repo/semantics/openAccess European neurology. - 2013 Adult Aged Aged, 80 and over Disorders of Excessive Somnolence Female Humans Male Middle Aged Narcolepsy Olfaction Disorders Parkinson Disease Restless Legs Syndrome Sleep Smell Sleepiness at the time of testing impairs olfactory performance. http://purl.org/coar/resource_type/c_6501