title: Apathy and olfactory dysfunction in early Parkinson's disease.
abstract: OBJECTIVE
  Olfactory and emotional dysfunctions are very common in patients with Parkinson's disease (PD). Olfaction and emotions share common neuroanatomical substrates. Therefore, in this study, we evaluated the association between olfactory and emotional dysfunctions in patients with PD.
  
  
  METHODS
  Parkinson's disease patients who had been assessed for their olfactory function and neuropsychiatric symptoms including emotional dysfunction were included. A logistic regression analysis was performed to evaluate the association between low olfaction and different neuropsychiatric symptoms.
  
  
  RESULTS
  The patients with low olfaction (cross cultural smell identification test score ≤ 6) showed a higher prevalence of apathy when compared with those with high olfaction, whereas the frequencies of other neuropsychiatric symptoms were comparable between the two groups. A multivariate logistic regression analysis revealed that the presence of apathy/indifference [odds ratio (OR) = 2.859, p = 0.007], age 70 years or more (OR = 2.281, p = 0.009), and the male gender (OR = 1.916, p = 0.030) were significantly associated with low olfaction.
  
  
  CONCLUSIONS
  Our results demonstrate that apathy/indifference is a unique emotional dysfunction associated with olfactory dysfunction in PD. The findings also suggest that PD patients with low olfaction have a high prevalence of apathy.
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University Wonju College of Medicine, Wonju, Korea ; Department of Neurology, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Hong
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University Wonju College of Medicine, Wonju, Korea ; Department of Neurology, Bundang Jesaeng General Hospital, Seongnam, Korea.
authors.forename: Mun Kyung
authors.initials: MK
authors.lastname: Sunwoo
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Ham
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Jae Jung
authors.initials: JJ
authors.lastname: Lee
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University Wonju College of Medicine, Wonju, Korea ; Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Phil Hyu
authors.initials: PH
authors.lastname: Lee
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Young H
authors.initials: YH
authors.lastname: Sohn
keywords: Apathy; Emotion; Hyposmia; Neuropsychiatric; Parkinson’s disease