Freezing is a debilitating phenomenon that reduces quality of life for people withParkinson's disease (PwPD). This study tests the hypothesis that: 1) freezing is linked to executive dysfunction; 2) freezing is a global motor phenomenon, not limited to gait. We compared 14 PwPD to 16 controls. Several aspects of executive function were measured using pro- and anti-saccade tasks under gap and overlap timing conditions, where the gap effect is defined as the reduction in saccade latency associated with the removal of fixation before target presentation. As predicted, results showed larger anti-saccade gap effects in PwPD with than without FOG, and that the pro-saccade gap effect predicted FOG severity in PwPD with FOG. PwPD also demonstrated impaired performance on reaching and walking tasks designed to elicit freezing. These findings strengthen the evidence that executive dysfunction, measured by saccade tasks, is linked to freezing in PwPD.
Author Keywords: executive function, eye movements, freezing of gait, freezing of upper limbs, Parkinson's disease