Protective Step Training in Parkinson's Disease

The primary purpose of this project is to determine the preliminary effectiveness of protective step training to improve balance and reduce falls in people with Parkinson's disease (PD) and postural disturbances. A secondary purpose is to understand which baseline patient characteristics predict responsiveness to treatment. By informing 1) the effectiveness of a promising rehabilitative intervention, and 2) the selection of the participants that will be most responsive to treatment, these data may enhance clinicians' ability to treat balance disturbances in people with PD. Importantly, protective step training, described in this proposal, can be quickly deployed in the clinic at minimal cost. Therefore, if shown to be effective via this and subsequent trials, this approach can be easily integrated into care, immediately impacting a large number of people with PD.

This project contains 3 aims: Aims 1 and 2 address the primary goal of this project: Determining the effectiveness of protective step training. Aim 1 will test whether perturbation training can improve protective stepping in people with PD with postural dysfunction. Aim 2 will test whether improvements are retained over 2 months and generalize to untrained perturbation tasks (which may be important for real world situations). Importantly, investigators will also gather exploratory data regarding the effect of perturbation training on falls. Aim 3 addresses the secondary goal of this project: Determining for whom protective step training is most beneficial. Aim 3 will relate behavioral factors and neuroimaging outcomes to the magnitude of improvement in protective stepping. All aims will be tested in people with PD who have postural disturbances. To complete these aims, participants will undergo 12 visits to the laboratory over the course of about 5 months. These will include 6 "training visits" over the course of 2 weeks, surrounded by 6 "assessment" visits before and after the training. During assessment visits, investigators will assess the ability to step quickly in response to a loss of balance (e.g. a slip), as well as thinking assessments and, if eligible, investigators will complete an MRI. During training visits, investigators will train the ability to step quickly in response to a slip. In this study, participants will serve as their own controls. As such, there is no randomization to multiple groups.

Participants will be assessed before and after a 2-week baseline period, and again before and after a 2 week "protective step training period. Participants will also be assessed 2 months later at a follow-up visit.

Participants will undergo 6, 1 hour visits (over the course of 2 weeks) where they will be exposed to repeated slips on a treadmill.

MOS: Distance between the extrapolated center of mass and base of support at first foot contact after the slip

Cognition, measured as the total score on the "SCales for Outcomes in PArkinson's disease-COGnition" (SCOPA-COG)

SCOPA-COG: This scale characterizes cognitive capacity of several domains, and was developed specifically for people with PD. Range: 0-43 (higher score reflects better cognitive capacity). Subscales/domains are calculated, and the *total* score is calculated as the sum of each subscale.

Structural brain connectivity between the cortex (supplementary motor area), and basal ganglia (striatum)

Diffusion Tensor Imaging data (collected via MRI), will be collected and analyzed to characterize the structural connectivity specifically between the cortex and basal ganglia.

Number of falls will be recorded via fall calendar in the 2 month period prior to training (baseline) and the 2 month period following training (post)

Inclusion Criteria: Neurologist diagnosed PD Postural Instability / Gait Dysfunction (PIGD) Ability to stand unaided for 5 minutes Exclusion Criteria: non-PD related neurological pathology orthopedic impairments affecting balance

Individual participant data will not be shared outside of the primary investigator and backup contact, noted above.