title: From sweet to sweat: Hedonic olfactory range is impaired in Parkinson's disease.
abstract: BACKGROUND
  Olfactory dysfunction and neuropsychological symptoms like depression and anhedonia are common non-motor symptoms in Parkinson's disease (PD). The assessment of both functional domains includes clinical examination, olfactory testing, and standardized questionnaires. While olfaction is readily assessed by functional tests, the distinction of anhedonia as a separate symptom from other depressive symptoms is challenging. Thus, a test focusing on the assessment of hedonic olfaction may be helpful in the assessment of neuropsychological symptoms in PD.
  
  
  METHODS
  We examined anhedonia by evaluating the perception of pleasantness of odors in PD patients (n = 57) and healthy controls (n = 46). Pleasantness of odors was registered on a visual 9-point scale. For the assessment of anhedonia we used the Snaith-Hamilton-Pleasure-Scale (SHAPS). Depression was evaluated with the Zung Self-Rating Depression Scale and the Beck Depression Inventory II.
  
  
  RESULTS
  PD patients showed a substantial reduction in hedonic olfaction compared to controls (hedonic score: 1.5 vs. 2.2). Hyposmia, one of the most prevalent non-motor symptoms in PD, was a confounding factor. However, even normosmic PD patients showed a reduced hedonic olfaction compared to controls (hedonic score: 1.6 vs. 2.2). Furthermore, we observed a correlation between hedonic olfaction and the SHAPS-score for PD patients even though positive SHAPS-rating was observed in 9% of PD patients only, while no correlation to depression was present.
  
  
  CONCLUSIONS
  These findings suggest that reduced hedonic olfaction might be an additional neuropsychological feature, probably giving insights into changes in hedonic tone complementary to hyposmia and depression in PD.
authors.affiliation: Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Mrochen
authors.affiliation: Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany; Department of Neurology, University Hospital Erlangen, FAU, Schwabachanlage 6, 91054 Erlangen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Marxreiter
authors.affiliation: Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Kohl
authors.affiliation: Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Schlachetzki
authors.affiliation: Department of Experimental and Clinical Pharmacology, FAU, Krankenhausstr. 9, 91054 Erlangen, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Renner
authors.affiliation: Department of Neurology, University Hospital Erlangen, FAU, Schwabachanlage 6, 91054 Erlangen, Germany; Clinical Neuropsychology, Department of Psychology, Ludwig-Maximilians-University Munich, Leopoldstr. 13, 80802 Munich, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schenk
authors.affiliation: Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Winkler
authors.affiliation: Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany. Electronic address: jochen.klucken@uk-erlangen.de.
authors.forename: J
authors.initials: J
authors.lastname: Klucken
mesh_terms: D000368:Aged; D059445:Anhedonia; D016022:Case-Control Studies; D003863:Depression / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000503:physiopathology*; D055696:Olfactory Perception; D010300:Parkinson Disease / Q000503:physiopathology* / Q000523:psychology; D057181:Pleasure
keywords: Anhedonia; Depression; Hedonia; Non-motor symptoms; Olfaction; Parkinson's disease