title: Association between olfactory identification and parkinsonism in patients with non-affective psychosis.
abstract: Olfactory identification deficits (OIDs) are seen in schizophrenia patients and individuals at increased risk for psychosis but its pathophysiology remains unclear. Although dopaminergic imbalance is known to lie at the core of schizophrenia symptomatology, its role in the development of OIDs has not been elucidated yet. This study investigated the association between OIDs and symptoms of parkinsonism as a derivative of dopaminergic functioning.
  
  
  
  In 320 patients diagnosed with non-affective psychosis, olfactory identification performance was assessed by means of the Sniffin' Sticks task. Level of parkinsonian symptoms was assessed by means of the Unified Parkinson's Disease Rating Scale (UPDRS-III). By means of multiple linear regression with bootstrapping, the association between UPDRS and Sniffin' Sticks score was investigated while correcting for potential confounders. A Bonferroni corrected P-value of 0.007 was used.
  
  
  
  Higher UPDRS scores significantly predicted worse olfactory identification in patients with non-affective psychosis with an unadjusted b = -0.07 (95% CI -0.10 to -0.04) and an adjusted b = -0.04 (95% CI -0.07 to -0.01).
  
  
  
  Results provide preliminary evidence that the same vulnerability may underlie the development of parkinsonism and OIDs in patients with non-affective psychosis. Further investigation should evaluate the clinical value of OIDs as a marker of dopaminergic vulnerability that may predict psychosis.
authors.affiliation: Academic Medical Center, Academic Psychiatric Centre, Department of Early Psychosis, University of Amsterdam, Amsterdam, The Netherlands. juliameijer80@gmail.com.
authors.forename: Julia H
authors.initials: JH
authors.lastname: Meijer
authors.affiliation: Psychiatric Centre GGZ Centraal, Amersfoort, The Netherlands.|Department of Psychiatry and Psychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: van Harten
authors.affiliation: Academic Medical Center, Academic Psychiatric Centre, Department of Early Psychosis, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Carin J
authors.initials: CJ
authors.lastname: Meijer
authors.affiliation: Academic Medical Center, Academic Psychiatric Centre, Department of Early Psychosis, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Maarten W
authors.initials: MW
authors.lastname: Koeter
authors.affiliation: Department of Psychiatry and Rob Giel Research Center, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Richard
authors.initials: R
authors.lastname: Bruggeman
authors.affiliation: Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Wiepke
authors.initials: W
authors.lastname: Cahn
authors.affiliation: Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: René S
authors.initials: RS
authors.lastname: Kahn
authors.affiliation: Academic Medical Center, Academic Psychiatric Centre, Department of Early Psychosis, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: de Haan
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D055696:Olfactory Perception; D020734:Parkinsonian Disorders / Q000150:complications / Q000175:diagnosis*; D011618:Psychotic Disorders / Q000150:complications / Q000523:psychology*; D012678:Sensation Disorders / Q000150:complications / Q000523:psychology*; D055815:Young Adult
keywords: dopamine; extrapyramidal; olfaction; schizophrenia