Saccadic performance characteristics and the behavioural neurology of Tourette's syndrome

Objective-To better understand the neuropathological correlates of Tourette 's syndrome (TS), measures of saccadic eye movement performance were examin ed among patients with TS. Methods-A case-control design was used. Twenty one patients with DSM-IV TS (mean age 40.6 years (SD 11.0); 38% female) mainly recruited from UCSD Psyc hiatry Services, and a community based sample of 21 normal subjects (mean a ge 34.6 years (SD 13.4); 43% women) participated in this study. Participant s were administered ocular motor tasks assessing visual fixation, and the g eneration of prosaccades, predictive saccades, and antisaccades. Saccadic r eaction time, amplitude, duration, and mean and peak velocity were computed . Intrusive saccades during visual fixation and the proportion of correct a ntisaccade responses were also evaluated. Results-The groups had similar visual fixation performance. Whereas patient s with TS generated prosaccades with normal reaction times and amplitudes, their saccade durations were shorter and their mean velocities were higher than in normal subjects. During a prosaccade gap task, patients with TS exh ibited an increased proportion of anticipatory saccades (RTs<90). The propo rtion of ((express)) saccades (90<RTs<135) did not differ between groups. P atients with TS had fewer correct antisaccade responses than did normal sub jects, an effect accounted for by 19% of the patients. Antisaccade reaction times among patients with TS were increased during an overlap version of t he task. Conclusion-These findings suggest that TS mildly affects the ocular motor c ontrol circuitry associated with saccade inhibition.