Gait and attentional performance in freezers under methylphenidate.

BACKGROUND Attentional resources appear to be involved in the occurrence of FoG. The Parkgait study recently reported that methylphenidate reduces gait hypokinesia and freezing of gait (FoG) in advanced PD patients receiving STN-DBS in the off-dopaminergic drug condition. Methylphenidate is considered to improve attention. The primary objective of the present ancillary study was to determine whether methylphenidate reduced the interference between a cognitive task and gait in patients with FoG. The study's secondary objective was to compare attentional performance in methylphenidate-treated and placebo-treated patients. METHODS A total of 24 patients (from two centers) were included in the study. Patients were randomly assigned 1:1 to a three-month course of methylphenidate (1mg/kg/day) or placebo. Patients were assessed after an acute L-dopa challenge. The primary outcome criterion was the stride length ratio ((dual-task stride length minus free gait stride length)/free gait stride length). Trials with FoG episodes were excluded from the analysis. Secondary outcomes included changes in reaction times for computerized attention tasks and FoG severity. RESULTS When comparing patients receiving methylphenidate with those receiving placebo, we did not observe any significant differences in the interaction between the dual task and gait or in attentional performance. CONCLUSION As in the main Parkgait study, methylphenidate did not reduce gait hypokinesia in patients receiving dopaminergic treatment. Our present results suggest that the reduction in the number of FoG episodes previously observed in patients on methylphenidate was neither due to interaction between a dual-task and gait nor an increase in attentional performance.