title: Effect of olfactory impairment and white matter hyperintensities on cognition in Parkinson's disease.
abstract: BACKGROUND
  Although white matter hyperintensities (WMH) and olfactory dysfunction are independently associated with the cognitive impairments in Parkinson's disease (PD), the effects of simultaneous presence of these abnormalities remain unknown. Thus, we investigated the different effects of deep WMH and periventricular WMH on olfactory and cognitive performance and evaluated the additive effects of the concurrent presence of WMH and olfactory dysfunction on cognitive performance in PD.
  
  
  METHODS
  We enrolled 171 patients with non-demented PD whose WMH scores were assessed using a semi-quantitative visual rating system. The olfactory and cognitive performance was assessed using the Cross-Cultural Smell Identification (CCSI) test and the Seoul Neuropsychological Screening Battery. Additionally, the additive effects of concurrent WMH and olfactory dysfunction on cognitive performance were investigated using binary logistic regression.
  
  
  RESULTS
  The deep WMH score exhibited a significant negative correlation with the CCSI score (p = 0.026) but the total WMH and periventricular WMH did not. A multiple regression analysis revealed that the total WMH (β = -0.109, p = 0.011) and deep WMH (β = -0.153, p = 0.020) severities had significant negative correlations with semantic fluency. A logistic regression analysis revealed that the simultaneous presence of severe olfactory dysfunction and deep WMH was associated with a greater risk for the semantic fluency impairments (odds ratio = 15.909, p = 0.0005) compared to patients with mild deep WMH or high CCSI scores.
  
  
  CONCLUSIONS
  These data indicate that deep WMH was closely coupled with olfactory impairments and cognitive decline in PD. Moreover, the concurrent presence of severe deep WMH and olfactory impairments has a greater influence on semantic fluency.
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Ham
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Jae Jung
authors.initials: JJ
authors.lastname: Lee
authors.affiliation: Department of Neurology, Bundang Jesaeng General Hospital, Seongnam, South Korea.
authors.forename: Mun-Kyung
authors.initials: MK
authors.lastname: Sunwoo
authors.affiliation: Department of Neurology, Yonsei University Wonju College of Medicine, Wonju, South Korea.
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Hong
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Young H
authors.initials: YH
authors.lastname: Sohn
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea; Severance Biomedical Science Institute, Seoul, South Korea. Electronic address: phisland@chol.net.
authors.forename: Phil Hyu
authors.initials: PH
authors.lastname: Lee
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D003072:Cognition Disorders / Q000000981:diagnostic imaging* / Q000209:etiology*; D056344:Executive Function; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D000857:Olfaction Disorders / Q000000981:diagnostic imaging / Q000209:etiology*; D010300:Parkinson Disease / Q000150:complications*; D012372:ROC Curve; D012044:Regression Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D066127:White Matter / Q000000981:diagnostic imaging* / Q000473:pathology
keywords: Cognition; Olfaction; Parkinson's disease; White matter hyperintensities