Novel challenges to gait in Parkinson's disease: the effect of concurrent music in single- and dual-task contexts.

Objective: To investigate the effect of concurrent music on parkinsonian gait in single- and dual-task contexts.

Design: A counterbalanced repeated-measure design.

Setting: A university balance research laboratory.

Participants: People with idiopathic Parkinson's disease (PD) (n=10) (67+/-7 y) and healthy age-matched (65+/-6 y) control subjects (n=10).

Intervention: Subjects walked at a self-selected pace along an unobstructed walkway in 4 differing test conditions. Test conditions were differentiated by the presence of music accompaniment (no music/music) and the presence of a secondary cognitive task (single/dual). Single- and dual-task conditions were randomized; trials were blocked by the presence of music and counterbalanced between subjects. Music was self-selected by subjects. The cognitive task consisted of serial subtractions (3's). Subjects were not instructed to attend to the music nor were they provided with instructions regarding task prioritization.

Main Outcome Measures: Mean gait velocity, stride length, and the percentage of the gait cycle spent in double-limb support.

Results: Gait among the PD patients was adversely affected by concurrent music. In contrast, gait performance in the control subjects showed no significant difference between no music and music conditions. The added requirement of a cognitive task differentially influenced gait performance in PD patients and control subjects, with PD patients displaying a further decrease in spatiotemporal parameters of gait and control subjects displaying a marginal improvement.

Conclusions: Gait impairments associated with PD are exacerbated in the presence of concurrent music, an effect that is further exaggerated by the addition of a cognitive task. These results have implications for patient safety in multitasking situations.