Gait Initiation Difficulty and Anticipatory Postural Adjustment (APA) Impairment in People With PD - Evaluation and Training

Gait initiation (GI) difficulty is common in people with Parkinson's disease (PD). Studies showed that the GI difficulty was related to impaired anticipatory postural adjustments (APA). In healthy people, two phases of APA related center of pressure (COP) shifting were observed before GI. In people with PD, delay and decrease amplitude of APA or abnormal multiple APAs were observed during GI.

Conventional balance tests record the maximum displacement and/or velocity of Center of pressure (COP). However, these variables could not show the performance of APA. Previous studies suggested that balance and gait initiation were controlled by separate neural circuitries. This could explain why the conventional COP measurement did not correlate to GI very well.

It is important to develop GI related APA tests and trainings. Researchers found that a perturbation applied before the COP displacement during GI could delay both GI and APA. This indicates that COP displacement has APA components. Our pilot study shows that there is a reverse direction of COP displacement before voluntary COP displacement, suggesting the existence of APA.

This three year project will evaluate the relationship of the APA of voluntary COP displacement and the APA of GI, establish the APA test for PD, and investigate the effect of APA training on GI in people with PD.

In the first year, 20 people without disability will be recruited. The APA before voluntary COP displacement test, APA before GI, and gait performance will be evaluated. In the second year, 15 people with PD and 15 healthy people will be recruited. Subjects will receive GI test, gait test, and APA before voluntary COP displacement test. The relationship between different types of APA will be established for PD and healthy people. In the third year, 30 people with PD will be randomized into APA training group, balance group, and control group. The different training effect will be evaluated especially on GI, gait performance, and freezing of gait.

This project will advance the knowledge of mechanism of GI difficulty. The result of this project can be applied to clinical rehabilitation of people with GI difficulty.