Bradykinesia in Huntington's disease. A prospective, follow-up study

Bradykinesia is a frequent finding in Huntington's disease (HD), but some aspects are presently unknown; including the natural evolution of bradykinesia over time and the correlation between bradykinesia and functional capacity. We studied the motor performance of 20 genetically confirmed patients with HD (age: 40+/-10.8 years; age at onset 33.6+/-11 years; total functional capacity (TFC): 9.57+/-3; UHDRS total motor scale: 31.4+/-13, triplet length (CAG)n: 46.7+/-4 triplets). These patients were studied in baseline conditions and after 18.7+/-6 months of follow-up. In addition, HD patients were compared with 20 age-matched normal controls. Motor study included the four CAPIT timed tests commonly used for Parkinson's disease: pronation-supination (PS), finger dexterity (FD), movement between two points (MTP) and walking test (WT). HD patients were significantly slower than controls in all motor tasks. A significant deterioration occurred over time in three of the four motor tasks (especially FD and WT). A significant correlation between timed tests and TFC score was found (for MTP, r: -0.845; p < 0,0001). In addition a significant correlation between timed tests and the UHDRDS total motor scale was also found (for MTP, r: 0.864; p < 0.0001). In conclusion, simple timed motor tests can detect a deterioration of motor activity over time in HD. Timed tests might be useful to follow the natural evolution of HD and to assess the efficacy of new therapies.