Role of attentional resources on gait performance in Huntington's disease.

Patients with Huntington's disease (HD) suffer from cognitive deficits with impaired executive functions, including limited attentional resources. We sought to use a dual-task paradigm to evaluate attentional demands and the ability of patients with HD to concentrate on two tasks simultaneously. We analyzed the interference effects of cognitive and motor tasks on walking in HD and the contribution of clinical symptoms to gait disturbances. Patients and controls were asked to perform either a motor task (carrying a tray with four glasses), a cognitive task (counting backwards), or no task at all while walking at their preferred speed. Kinematic spatial parameters, temporal parameters, and angular parameters related to gait were recorded in 15 patients and 15 controls by means of a videomotion analysis system. Gait instability was assessed using the stride-to-stride variability of the various gait parameters. For patients with HD, performing a concurrent cognitive task resulted in a lower gait speed (compared with free walking), with decreased cadence and stride length. However, this effect was not observed in controls. Performing a motor task did not change any kinematic gait parameters in either HD or control subjects. We found correlations between gait speed in the dual cognitive/walking task on one hand and the motor UHDRS score, cognitive status and executive function on the other. Patients with HD had greater difficulty walking while performing a concurrent cognitive task; the drain on attentional resources deteriorated walking performance.