The influence of dopaminergic medication on gait automaticity in Parkinson's disease.

Dual-tasking studies have shown that gait automaticity in Parkinson's disease (PD) is significantly diminished. Additionally, it's well accepted that dopaminergic medication improves single-task gait. But, how dopaminergic medication influences gait automaticity in PD has not been sufficiently understood. This study was a cross-sectional design, where sixteen subjects with PD completed single- and dual-task walking for 3 min off and on medication. Gait velocity, cadence, and stride length were measured. Kinematic variables included mean, maximum, and SD angles of bilateral hip, knee, and shoulder joints. Data were analyzed with a repeated measures ANOVA and a linear mixed effects repeated measures model. Dopaminergic medication significantly increased gait velocity (p = 0.007) and stride length (p = 0.046). After controlling for gait velocity, several kinematic variables were also improved with medication. Despite medication state, dual-tasking significantly interfered with cadence (p = 0.042), stride length (p < 0.001), and some kinematic measures. Dopaminergic medication mostly increased the hip and knee joint angles, while dual-tasking primarily decreased the hip joint angles on the less PD-affected side. There was no significant interaction between medication status and task condition. The significant differences in dual-tasking between off- and on-medication states indicates that motor improvements from taking medications improved dual-tasking. However, the lack of significant interactions and secondary task effects does not support a medication-induced improvement in automaticity.