Objective: To confirm the feasibility of daily life physical activity monitoring in PSP using a single activPAL sensor, and to examine preliminary associations between overall sedentary behavior, patient demographics, and home exercise per diary records.
Background: People with PSP have limited activity levels in daily life due to balance impairment and fear of falling. Two prior studies have examined home activity monitoring in PSP using the activPAL sensor. One study found decreased walking duration in PSP compared to Parkinson’s, ataxia, and age matched controls [1]; the second study found that low walking activity in PSP correlated with subsequent falls [2]. To our knowledge no prior studies have examined the relationship between disease severity, home exercise patterns, and the SI in PSP.
Method: Two individuals with PSP wore an activPAL activity monitor on their thigh for 7 continuous days and their care partners recorded sleep and exercise sessions. We collected demographics, a Montreal Cognitive Assessment, and an on-medication PSP Rating Scale (PSPRS). The SI was calculated as the percentage of the waking day spent in sedentary behaviors.
Results: Subject one: 79 year-old male, MOCA 24/30, PSPRS 23/100 (gait and midline subscore 3), exercise sessions over 7 days=5, average SI over 7 days= 79%.
Subject two: 63 year-old male, MOCA 21/30, PSPRS 41/100 (gait and midline subscore 14), exercise sessions over 7 days=3, average SI over 7 days= 91%.
See Figure 1. The Sedentary Index (SI) shows the proportion of the waking day spent in sedentary behaviors such as sitting or resting quietly.The reference population is drawn from 4,494 days of accelerometer data from 632 adults aged 63 ±8 years (NCI IDATA cohort study).
Conclusion: Collection of 7 days of continuous data from a single activPAL monitor is feasible for patients and their care partners. Preliminarily, we see a correspondence between increased disease severity in PSP, decreased home exercise, and increased SI. We anticipate collecting data from additional participants by the October MDS meeting. The sedentary index may be a viable outcome in future clinical trials.
The Sedentary Index (SI) vs Reference Population
References: [1] Klenk J, Srulijes K, Schatton C, Schwickert L, Maetzler W, Becker C, Synofzik M. Ambulatory Activity Components Deteriorate Differently across Neurodegenerative Diseases: A Cross-Sectional Sensor-Based Study. Neurodegener Dis. 2016;16(5-6):317-23. doi: 10.1159/000444802. Epub 2016 May 21. PMID: 27197840.
[2] Srulijes K, Klenk J, Schwenk M, Schatton C, Schwickert L, Teubner-Liepert K, Meyer M, K C S, Maetzler W, Becker C, Synofzik M. Fall Risk in Relation to Individual Physical Activity Exposure in Patients with Different Neurodegenerative Diseases: a Pilot Study. Cerebellum. 2019 Jun;18(3):340-348. doi: 10.1007/s12311-018-1002-x. PMID: 30617629.
To cite this abstract in AMA style:
M. Dale, C. Silva-Batista, A. Ragothaman, Z. Nhem, A. Lawston, G. Harker, D. Maxwell, C. Speirs, D. Loudon, M. Mancini. The Sedentary Index (SI) for Daily Life Activity Monitoring in Progressive Supranuclear Palsy (PSP) [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/the-sedentary-index-si-for-daily-life-activity-monitoring-in-progressive-supranuclear-palsy-psp/. Accessed October 5, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/the-sedentary-index-si-for-daily-life-activity-monitoring-in-progressive-supranuclear-palsy-psp/