title: Olfactory dysfunction in idiopathic REM sleep behavior disorder.
abstract: BACKGROUND
  Olfactory dysfunction is frequently observed in patients with idiopathic REM sleep behavior disorder (iRBD) such as Parkinson's disease or dementia with Lewy bodies.
  
  
  METHODS
  Olfactory function tests using Sniffin' Sticks and Odor Stick Identification Test for Japanese (OSIT-J) were performed in 73 consecutive middle-aged (range, 50-69 years) patients with iRBD, 33 consecutive older-aged (71-82 years) patients with iRBD, and 28 control subjects (55-70 years).
  
  
  RESULTS
  Odor identification was more frequently impaired than odor threshold or discrimination among the iRBD group and allowed better discrimination between the middle-aged iRBD group and age-adjusted control subjects. The area under the curve for threshold, discrimination, identification, TDI score and OSIT-J score determined from receiver operating characteristic curves were 0.831 (0.753-0.909), 0.761 (0.666-0.855), 0.938 (0.894-0.982), 0.939 (0.897-0.981), and 0.965 (0.931-0.999), respectively. Discrimination and identification scores were significantly lower in the older-aged iRBD group than in the middle-aged iRBD group. A significant correlation was observed between the identification score on Sniffin' Sticks and OSIT-J score (r=0.5910, P<0.0001, n=106, Spearman's rank).
  
  
  CONCLUSIONS
  Anosmia/hyposmia may be a feature of iRBD. Olfactory dysfunction in iRBD is a consistent, widespread central nervous abnormality of different olfactory modalities with different cognitive complexity.
authors.affiliation: Department of Neurology, Center of Sleep Medicine, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan. miyatomo@dokkyomed.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Masaoki
authors.initials: M
authors.lastname: Iwanami
authors.forename: Koichi
authors.initials: K
authors.lastname: Hirata
authors.forename: Mina
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Masaki
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D044466:Asian People; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D020961:Lewy Body Disease / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D010300:Parkinson Disease / Q000453:epidemiology; D017286:Polysomnography; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis / Q000453:epidemiology*; D012684:Sensory Thresholds; D012903:Smell