title: Cognitive impairment and PD patients' capacity to consent to research.
abstract: OBJECTIVE
  To examine how cognitive impairment affects Parkinson disease (PD) patients' research consent capacity.
  
  
  METHODS
  A cross-sectional study of 90 patients with PD, divided using Mattis Dementia Rating Scale-2 scores into 3 groups of 30 (normal, borderline, and impaired), and 30 neurologically normal older adults completed 2 capacity interviews (an early-phase randomized and controlled drug trial and a sham-controlled surgical implantation of genetic tissue) using the MacArthur Competence Assessment Tool for Clinical Research. Expert clinicians used the interviews to classify the patients as either capable or not capable of providing their own informed consent. These judgments were compared with performance on the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE).
  
  
  RESULTS
  Cognitively normal PD patients typically scored well on the capacity measures. In contrast, patients with impaired cognition were not capable of providing their own informed consent: 17% (5/30) on the drug trial and 3% (1/30) on the surgery trial were judged capable. Patients with borderline impairment showed adequate performance on measures of appreciation and reasoning, but impaired performance on understanding the drug trial compared with normal controls and normal PD patients, and on understanding the surgery trial compared with normal controls. Sixty-seven percent (20/30) on the drug trial and 57% (17/30) on the surgery trial were judged capable of consent. Receiver operating characteristic analyses showed that the MMSE and MoCA could detect the likelihood of impaired capacity, with the MoCA demonstrating greater sensitivity.
  
  
  CONCLUSIONS
  PD patients with borderline cognitive impairment have impairments in their decisional capacity. The MoCA may be useful to identify the patients at risk of impaired capacity.
authors.affiliation: University of Pennsylvania, Philadelphia, PA, USA. Jason.Karlawish@uphs.upenn.edu
authors.forename: Jason
authors.initials: J
authors.lastname: Karlawish
authors.forename: Mark
authors.initials: M
authors.lastname: Cary
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Moelter
authors.forename: Andrew
authors.initials: A
authors.lastname: Siderowf
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Sullo
authors.forename: Sharon
authors.initials: S
authors.lastname: Xie
authors.forename: Daniel
authors.initials: D
authors.lastname: Weintraub
mesh_terms: D000368:Aged; D003072:Cognition Disorders / Q000175:diagnosis / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007258:Informed Consent; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000175:diagnosis / Q000503:physiopathology*; D012372:ROC Curve; D012106:Research
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