title: Slowing of number naming speed by King-Devick test in Parkinson's disease.
abstract: BACKGROUND
  The King-Devick (KD) test measures the speed of rapid number naming, and is postulated to require fast eye movements, attention, language, and possibly other aspects of cognitive functions. While used in multiple sports concussion studies, it has not been applied to the field of movement disorders.
  
  
  METHODS
  Forty-five Parkinson's disease (PD), 23 essential tremor (ET), and 65 control subjects were studied. Subjects performed two trials of reading out loud single-digit numbers separated by varying spacing on three test cards that were of different formats. The sum time of the faster trial was designated the KD score and compared across the three groups.
  
  
  RESULTS
  PD patients had higher (worse) KD scores, with longer reading times compared to ET and control subjects (66 s vs. 49 s vs. 52 s, p < 0.001, adjusting for age and gender). No significant difference was found between ET and control (Δ = -3 s, 95% CI: -10 to 4).
  
  
  CONCLUSIONS
  This is the first study of the King-Devick Test in Parkinson's disease. PD patients were found to have a slower rapid number naming speed compared to controls. This test may be a simple and rapid bedside tool for quantifying correlates of visual and cognitive function in Parkinson's disease.
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, Scottsdale, AZ, USA.
authors.forename: Tanya P
authors.initials: TP
authors.lastname: Lin
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, Scottsdale, AZ, USA. Electronic address: cadler@mayo.edu.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Adler
authors.affiliation: Department of Biostatistics, Mayo Clinic College of Medicine, Scottsdale, AZ, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Hentz
authors.affiliation: Department of Neurology, NYU School of Medicine, New York, NY, USA.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Balcer
authors.affiliation: Department of Neurology, NYU School of Medicine, New York, NY, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Galetta
authors.affiliation: King-Devick Test LLC, Oakbrook Terrace, IL, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Devick
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology; D020329:Essential Tremor / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D012438:Saccades / Q000502:physiology
keywords: Cognitive function; Eye movements; Parkinson's disease