Huntington's disease: changes in saccades and hand-tapping over 3 years.

Saccades and hand-tapping are both potential biomarkers in patients with Huntington's disease (HD). While it is well known that patients with manifest Huntington's disease display abnormalities in both of these tasks, less is known about how these abnormalities progress over time, or to what extent premanifest patients are affected. This study was designed to address these issues. We examined premanifest and manifest Huntington's cohorts, together with a group of controls, over a 3-year period. Data were collected using a portable head-mounted saccadometer and a computerised hand-tapping device. Both premanifest and manifest Huntington's disease patients display significant and systematic changes from year to year in the parameters describing saccadic latency, while controls remain unchanged. By contrast, although hand-tapping was abnormal in HD patients, annual changes were much smaller. Measuring the rate of progression of saccadic abnormalities in manifest HD patients may provide a way to track disease progression, and thus help to evaluate novel therapies to modify the disease. The clear-cut progression in saccadic abnormalities in the premanifest group may prove useful in the future as a predictor of time to disease onset.