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