title: Lithium Use in Older Adults is Associated with Increased Prescribing of Parkinson Medications.
abstract: OBJECTIVE
  To test the hypothesis of an increased incidence of antiparkinson drug prescribing or Parkinson disease (PD) diagnostic codes after chronic lithium treatment compared with chronic valproic acid or antidepressant treatment among older adults.
  
  
  METHODS
  A retrospective cohort study using healthcare administrative databases in Ontario, Canada included 1,749 lithium users, 1,787 valproic acid users, and 285,154 other antidepressant users ≥ 66 years old having used the drug continuously in monotherapy for at least 1 year. Outcome measures were start of (1) a dopaminergic medication (levodopa or a dopamine agonist), (2) any antiparkinson drug (levodopa, dopamine agonists, anticholinergic medication, amantadine, monoamine oxidase B inhibitors), (3) any antiparkinson drug or a diagnostic code for PD, and (4) any antiparkinson drug in the absence of a diagnostic code for PD.
  
  
  RESULTS
  For patients with no previous antipsychotic use, lithium monotherapy was associated with an increased incidence of dopaminergic drug use (adjusted HR: 1.87; 95% CI: 1.06-3.30) and an increased incidence of antiparkinson drug use or a PD diagnosis (adjusted HR: 1. 68; 95% CI: 1.13-2.48) compared with antidepressant monotherapy.
  
  
  CONCLUSIONS
  Chronic lithium use is associated with an increased incidence of dopaminergic drug use compared with antidepressants, identifying a prescribing cascade related to lithium use in the elderly. Whether this reflects inappropriate treatment of action tremor or treatment of drug-induced parkinsonism should be addressed by a close examination of prescribing practices.
authors.affiliation: Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital and The Edmond J. Safra Program in Parkinson's Disease, Toronto, Ontario, Canada; University of Toronto, Toronto, Ontario, Canada. Electronic address: cmarras@uhnresearch.ca.
authors.forename: Connie
authors.initials: C
authors.lastname: Marras
authors.affiliation: University of Toronto, Toronto, Ontario, Canada; Division of Geriatric Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Nathan
authors.initials: N
authors.lastname: Herrmann
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
authors.forename: Hadas D
authors.initials: HD
authors.lastname: Fischer
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Kinwah
authors.initials: K
authors.lastname: Fung
authors.affiliation: University of Toronto, Toronto, Ontario, Canada; Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; Department of Family Medicine, University of Alberta, Edmonton, Alberta, Canada; Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gruneir
authors.affiliation: University of Toronto, Toronto, Ontario, Canada; Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Paula A
authors.initials: PA
authors.lastname: Rochon
authors.affiliation: University of Toronto, Toronto, Ontario, Canada; Division of Geriatric Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Soham
authors.initials: S
authors.lastname: Rej
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Simone
authors.initials: S
authors.lastname: Vigod
authors.affiliation: Institute for Clinical Evaluative Sciences, Queen's University, Kingston, Ontario, Canada.
authors.forename: Dallas
authors.initials: D
authors.lastname: Seitz
authors.affiliation: University of Toronto, Toronto, Ontario, Canada; Division of Geriatric Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Kenneth I
authors.initials: KI
authors.lastname: Shulman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000928:Antidepressive Agents / Q000627:therapeutic use*; D018692:Antimanic Agents / Q000627:therapeutic use; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D015259:Dopamine Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D018020:Lithium Compounds / Q000627:therapeutic use*; D008297:Male; D009864:Ontario / Q000453:epidemiology; D010300:Parkinson Disease / Q000188:drug therapy* / Q000453:epidemiology; D012189:Retrospective Studies; D014635:Valproic Acid / Q000627:therapeutic use
chemical_list: D000928:Antidepressive Agents; D018692:Antimanic Agents; D000978:Antiparkinson Agents; D015259:Dopamine Agents; D018020:Lithium Compounds; D014635:Valproic Acid
keywords: bipolar disorder; dopaminergic medication; lithium; treatment; tremor