The combined effect of REM sleep behavior disorder and hyposmia on cognition and motor phenotype in Parkinson's disease

Sung Hoon Kang, Hye Mi Lee, Woo Keun Seo, Ji Hyun Kim, Seong Beom Koh

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Background Olfactory dysfunction and REM sleep behavior disorder (RBD) are recognized as pre-motor symptoms of Parkinson's disease (PD). Cognitive dysfunction is observed at a high rate even in the early stages of PD as an important non-motor symptom. PD has been classified in different subtypes and it is unknown if olfactory dysfunction and RBD occur more often in one particular subtype. We investigated the relationship between olfactory impairment, RBD, initial cognitive performance and motor phenotype in PD. Method Nighty-eight patients with drug-naïve idiopathic PD who visited the Movement Disorders Unit of Korea University Guro Hospital, Seoul, Korea from March 2012 to February 2014 were retrospectively included. Patients were divided into tremor-dominant-type and akinetic-rigid-type PD subgroups using part III of the Unified Parkinson's Disease Rating Scale. Olfaction was assessed by the Cross Cultural Smell Identification Test. RBD was screened using screening questionnaires. Initial cognitive function was assessed with Mini–Mental State Examination. Result The PD-normosmia group had higher MMSE scores (p = 0.008). PD patients who have both RBD and olfactory dysfunction had lower MMSE scores (p = 0.013). Presence of both RBD and hyposmia in PD patients was more strongly correlated with poor cognitive dysfunction. PD patients with RBD and/or hyposmia primarily exhibited the akinetic-rigidity phenotype. Conclusion Olfactory dysfunction and RBD differed according to the motor phenotypes of PD. This suggests that olfactory dysfunction and RBD might relate to prognosis in patients with PD. Patients who have both hyposmia and RBD were more likely to exhibit cognitive dysfunction.

Original languageEnglish
Pages (from-to)374-378
Number of pages5
JournalJournal of the Neurological Sciences
Volume368
DOIs
Publication statusPublished - 2016 Sep 15

Keywords

  • Cognitive dysfunction
  • Hyposmia
  • Motor phenotype
  • Parkinson's disease
  • REM sleep behavior disorder

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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