title: Cognition and Dopamine D2Receptor Availability in the Striatum in Older Patients with Schizophrenia.
abstract: To assess the impact of reducing the dose of antipsychotics on cognition and dopaminergic D2receptor availability in the whole striatum, and identify their relationship in patients with schizophrenia aged 50 years or older.
  
  
  
  Open-label prospective PET [11C]-raclopride study.
  
  
  
  A tertiary care center outpatient setting.
  
  
  
  Thirty-seven clinically stable participants with schizophrenia or schizoaffective disorder, aged 50 years or greater, and having been treated with olanzapine or risperidone monotherapy at the same dose for at least 6 months.
  
  
  
  Gradual reduction in their olanzapine or risperidone daily dose of up to 40%.
  
  
  
  Clinical and cognitive assessments, and [11C]-raclopride PET to determine D2receptor availability at baseline and after the dose reduction. Main outcome measures were overall cognition and D2receptor availability in whole striatum.
  
  
  
  Reducing the antipsychotic dose resulted in an increase in D2receptor availability in the whole striatum and an association between D2receptor availability and overall cognition despite lack of change in the latter. There was also an association between change in D2receptor availability and change in overall cognition.
  
  
  
  Our findings suggest that optimizing D2receptor availability by reducing antipsychotic dose allows this system to contribute more significantly to cognitive function in patients with schizophrenia. This uncovered association could be harnessed by cognitive-enhancing interventions.
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. Electronic address: Tarek.Rajji@camh.ca.
authors.forename: Tarek K
authors.initials: TK
authors.lastname: Rajji
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Benoit H
authors.initials: BH
authors.lastname: Mulsant
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakajima
authors.affiliation: Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Fernando
authors.initials: F
authors.lastname: Caravaggio
authors.affiliation: Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uchida
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Philip
authors.initials: P
authors.lastname: Gerretsen
authors.affiliation: Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Wanna
authors.initials: W
authors.lastname: Mar
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Pollock
authors.affiliation: Department of Psychiatry, Faculties of Medicine and Health Science, University of Malta, Msida, Malta.
authors.forename: David C
authors.initials: DC
authors.lastname: Mamo
authors.affiliation: Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Ariel
authors.initials: A
authors.lastname: Graff-Guerrero
mesh_terms: D000368:Aged; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001569:Benzodiazepines / Q000008:administration & dosage / Q000494:pharmacology; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging / Q000378:metabolism*; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077152:Olanzapine; D049268:Positron-Emission Tomography; D011618:Psychotic Disorders / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D018967:Risperidone / Q000008:administration & dosage / Q000494:pharmacology; D012559:Schizophrenia / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism
chemical_list: D014150:Antipsychotic Agents; C581293:DRD2 protein, human; D017448:Receptors, Dopamine D2; D001569:Benzodiazepines; D020891:Raclopride; D018967:Risperidone; D000077152:Olanzapine
keywords: D(2) receptor; PET; antipsychotic; cognition; late-life schizophrenia