Effects of exercise on gait and motor imagery in people with Parkinson disease and freezing of gait. (August 2018) - Myers, Peter S.
Abstract: Introduction: Exercise improves gait in Parkinson disease (PD), but whether exercise differentially affects people with PD with (freezers) and without freezing of gait (non-freezers) remains unclear. This study examines exercise's effects on gait performance, neural correlates related to these effects, and potential neural activation differences between freezers and non-freezers during motor imagery (MI) of gait. Methods: Thirty-seven participants from a larger exercise intervention completed behavioral assessments and functional magnetic resonance imaging (fMRI) scans before and after a 12-week exercise intervention. Gait performance was characterized using gait velocity and stride length, and a region of interest (ROI) fMRI analysis examined task-based blood oxygen-level dependent (BOLD) signal changes of the somatomotor network (SMN) during MI of forward (IMG-FWD) and backward (IMG-BWD) gait. Results: Velocity (F(1, 34) = 55.04, p < 0.001) and stride length (F(1, 34) = 77.58, p < 0.001) were significantly lower for backward versus forward walking in all participants. The ROI analysis showed freezers had lower BOLD signal compared to non-freezers in the cerebellum (F(1, 32) = 7.01, p = 0.01), primary motor (left: F(1, 32) = 7.09, p = 0.01; right: F(1, 32) = 7.45, p = 0.01), and primary sensory (left: F(1, 32) = 9.59, p = 0.004; right: F(1, 32) = 8.18, p = 0.007) cortices during IMG-BWD only. The evidence suggests the exercise intervention did not affect gait or BOLD signal during MI. Conclusion: While all participants had significantly slower and shorter backward velocity and stride length, respectively, the exercise intervention had no effect. Similarly, BOLD signal during MI did not change with exercise; however, freezers had significantly lower BOLD signal during IMG-BWD compared to non-freezers. This suggests potential decreased recruitment of the SMN during MI of gait in freezers. Highlights: Freezers and non-freezers had similar forward and backward gait velocity. Somatomotor network activity was lower in freezers during imagined backward gait. Gait velocity and somatomotor network activity did not change after regular exercise.