While much is known about the effects of dual tasking on cyclical and continuous motor performance (e.g., locomotion), there is a paucity of information on the effect of dual tasking on the initiation of movement. Therefore, the purpose of this study was to investigate the effect of a concurrent cognitive task on gait initiation in three groups: patients with Parkinson disease, healthy older adults, and healthy young adults. We examined the anticipatory postural adjustment displacements and

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... cities during single-task gait initiation as well as two dual-task conditions: (1) 0-back + gait initiation and (2) 2-back + gait initiation. The Parkinson disease group exhibited less anticipatory postural adjustment displacement and velocity than their aged-matched healthy peers and young adults during the single-and dual-task gait initiation settings (p < 0.05). Of interest was the finding of no additional effect on anticipatory postural adjustment displacement or velocity of gait initiation during the dual-task conditions in any group, including the Parkinson disease group. More traditionally studied gait/balance dual-task paradigms have demonstrated both motor and cognitive decline. Therefore, our results may suggest a prioritization of more "intentional" movement task (e.g., gait initiation) while dual tasking in Parkinson disease. Abbreviations : ANOVA = analysis of variance, APA = anticipatory postural adjustments, GI = gait initiation, H&Y = Hoehn & Yahr, HOA = healthy older adults, HYA = healthy young adults, MANOVA = multivariate analysis of variance, MMSE = Mini-Mental State Examination, PD = Parkinson disease.