This is a single-arm, longitudinal, observational study on the use of wearable sensors and digital health technology to measure fall frequency and motor, speech, and cognitive function in patients with PSP over the course of approximately one year. Participants will perform supervised remote assessments monthly and in-person assessments approximately every 6 months.

The primary objective of this study is to determine the feasibility of using wearable sensors and digital health technology to remotely monitor patients with possible or probable PSP.

Secondary objectives are to measure PSP progression using sensor-derived motor and tablet-derived speech and cognitive measures.

In brief, approximately 85 individuals with possible or probable PSP, probable Parkinson's disease, possible or probable Multiple System Atrophy, and healthy controls, will be enrolled at 4-5 sites in the U.S. and followed for one year. During the monitoring period for PSP and MSA participants (1 year), a wearable pendant sensor (PAMSys, BioSensics) will be used to monitor falls and physical activity (step counts) of all participants during activities of daily living (ADL). Parkinson's and healthy control participants will be seen once at baseline only. On a monthly basis, participants will have televideo conferences with the sites to perform supervised gait and balance tasks while wearing 3 LEGSys (BioSensics) sensors. Using a study-supplied tablet, participants will also perform cognitive tests including fluency, color trails and go-no-go tapping tests. Participants will undergo more extensive testing every 3 months including the PSPRS, MoCA, quality of life questionnaires and functional rating scales which will be performed remotely (virtually). Approximately 6 months participants will undergo an in-person PSPRS (to coincide with their clinic appointments).

Inclusion Criteria:

• Clinical diagnosis of possible or probable PSP phenotype as defined by the 2017 MDS criteria, clinical diagnosis of at least probable PD as defined by the 2015 MDS criteria, or clinical diagnosis of at least probable MSA as defined by the 2022 MDS criteria, or healthy controls.
• Male or female, aged 18 to 89 years, inclusive.
• Fluent in reading and speaking English.
• Capable of providing informed consent based on the investigator's judgment.
• Able to comply with the protocol based on the investigator's judgment.
• Able to walk 10 feet unassisted.
• With access to a caregiver who is able to assist with all study-related procedures.

Exclusion Criteria:

• Any neurological, medical, or psychiatric condition that would preclude participation in study activities based on the investigator's judgment.
• A history of frequent falls defined as more than 5 falls/month or requirement of a walker to ambulate safely.

All participants with clinical diagnosis of possible or probable PSP, probable PD, or possible or probable MSA are eligible to participate in this study. Participants must be able to ambulate unassisted for 10 feet in order to perform gait and balance tests.