title: Loss of awareness of hyposmia is associated with mild cognitive impairment in Parkinson's disease.
abstract: BACKGROUND
  Hyposmia is a common non-motor symptom in Parkinson's disease (PD). However, patients with PD are sometimes unaware of their olfactory dysfunction, resulting in an under-diagnosis of this symptom. To determine whether the loss of awareness of hyposmia results from cognitive impairment in patients with PD, we investigated the relationship between the degree of hyposmia self-awareness and the cognitive status of non-demented PD patients.
  
  
  METHODS
  Thirty-one non-demented patients with PD and 20 healthy controls (HC) were assessed via a self-reported olfactory questionnaire and an odor identification test. PD patients were sub-classified as having mild cognitive impairment (PD-MCI) or as cognitively normal (PD-CN) (according to the current PD-MCI criteria). We compared the degree of hyposmia self-awareness between the PD-MCI and PD-CN groups.
  
  
  RESULTS
  The PD-MCI group scored the lowest on the odor identification test among all groups, whereas PD-MCI patients tended to rate their olfactory function higher on the self-reported olfactory questionnaire than PD-CN patients. Differences in the scores of subjective and objective olfactory measures between the PD-MCI and PD-CN groups were significant (p = 0.0069).
  
  
  CONCLUSIONS
  The loss of awareness of hyposmia is closely associated with mild cognitive impairment (MCI) in PD patients.
authors.affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Japan.
authors.forename: Iori
authors.initials: I
authors.lastname: Kawasaki
authors.affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Japan. Electronic address: t-baba@med.tohoku.ac.jp.
authors.forename: Toru
authors.initials: T
authors.lastname: Baba
authors.affiliation: Department of Neurology, National Hospital Organization Sendai-Nishitaga Hospital, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takeda
authors.affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Japan.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Mori
mesh_terms: D000368:Aged; D001364:Awareness; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000523:psychology*; D010300:Parkinson Disease / Q000523:psychology*
keywords: Awareness; Cognitive impairment; Olfaction; Parkinson's disease; Parkinson's disease with mild cognitive impairment