Reduced saccadic velocity and pupillary width in young onset Parkinson’s disease

Abstract

BackgroundPatients with Young onset Parkinson disease patients (YODP) are individuals with motor complications identical to late onset Parkinson’s disease (PD) but onset in early age. YOPD is a specific subgroup of PD and their performance on saccadic eye movements is not well established. This study evaluated saccadic eye movements in patients with YOPD (< 40 years at onset of illness). MethodsEye movements were recorded during saccadic eye movement tasks, induced by presentation of a visual target and reflexive saccadic task was administered. ResultsYOPD patients showed reduced saccadic velocity on reflexive saccadic task (Gap task) as compared to their age matched healthy controls. Additionally, pupil width in gap period and at saccade onset was measured. Pupil width was significantly smaller in patients with YOPD as compared to control subjects. ConclusionsReduced saccadic velocity implies that Parkinson’s disease affects saccadic circuitry in patients with YOPD reflecting impaired circuitry at the brainstem level. The reduced pupillary response in gap condition is attributed to deficits in motor preparedness in patients compared to controls.