BRADYKINESIA AND MOVEMENT PRECISION IN HUNTINGTONS-DISEASE

To determine whether bradykinesia in patients with Huntington's diseas e (HD) reflects impaired force production or an increased requirement for terminal visual guidance, II HD patients and matched controls perf ormed drawing movements with varying precision requirements. Participa nts used an electronic pen upon a WACOM SD420 graphics tablet to join targets of either IO or 20 mm diameter which were separated by a dista nce of 62.5 or 125 mm. While HD patients had slower movements, exhibit ing more cycles of acceleration and deceleration, patients were not di sproportionately affected by variations in target size or separation. Bradykinesia did not seem to be a product of impaired force production or increased reliance upon terminal visual guidance, since neither ac celerative or decelerative phases were specifically affected by HD. Ho wever, movements of HD patients were of less consistent duration, impl ying variability associated with internal cues regulating movement. Co pyright (C) 1966 Elsevier Science Ltd