Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jun 11:18:319-336.
doi: 10.2147/MDER.S522827. eCollection 2025.

Phybrata Digital Biomarkers of Age-Related Balance Impairments, Sensory Reweighting, and Intrinsic Fall Risk

John D Ralston  1 , Scott Stanley  2 , Joshua M Roper  1 , Andreas B Ralston  3
Affiliations

Phybrata Digital Biomarkers of Age-Related Balance Impairments, Sensory Reweighting, and Intrinsic Fall Risk

John D Ralston et al. Med Devices (Auckl). .

Abstract

Objective: To assess the utility of digital biomarkers derived from a head-mounted wearable physiological vibration acceleration (phybrata) sensor to quantify age-related balance impairments, sensory reweighting, and fall risks in older populations.

Methods: Data were collected and analyzed from 516 participants aged 77.7 ± 8.0 yrs (min 51 yrs, max 98 yrs, 334 females, 182 males) in 4 residential senior living communities. Participants first completed a questionnaire that included their fall history in the past 6 months. A 2-minute standing balance test was then carried out for each participant using the phybrata sensor (1 minute with eyes open, followed by 1 minute with eyes closed). Four balance performance biomarkers were derived from the phybrata time series data: eyes open (Eo) and eyes closed (Ec) phybrata powers, average phybrata power (Eo+Ec)/2, and Ec/Eo phybrata power ratio. Sensory reweighting biomarkers were derived from phybrata acceleration spectral density (ASD) distributions. Results are compared for participants with no reported fall history (NF) and those reporting one or more falls (FR) in the previous 6 months.

Results: All four phybrata balance performance biomarkers show significantly higher values for FR participants vs NF participants. As a fall risk biomarker, Ec phybrata power was found to have the strongest statistical correlation with the reported retrospective incidence of falls within the previous 6 months. The Ec phybrata biomarker also showed the strongest statistical difference between F and M participants. Phybrata sensory reweighting biomarkers quantify age-related impairments and sensory reweighting across sensory inputs (visual, vestibular, proprioceptive), central nervous system (CNS) processing, and neuromotor control (vestibulocollic reflex), revealing progressive reductions in visual and vestibular balance regulation and vestibulocollic head stabilization that are offset by an increasing reliance on proprioceptive balance control.

Conclusion: Phybrata digital biomarkers enable rapid objective assessment of progressive age-related balance impairments, sensory reweighting, and fall risks in older populations.

Keywords: age-related balance decline; balance performance; biomarker; fall risk; phybrata; presbystasis; sensory reweighting; vestibular; wearable sensor.

PubMed Disclaimer

Conflict of interest statement

John D Ralston is the co-founder and CEO of Neursantys, Inc., and has a financial interest in the company. In addition, he reports a US provisional patent application 63/741,968 pending to Neursantys Inc. Josh Roper is the co-founder and Vice President of Operations of Neursantys, Inc., and has a financial interest in the company. Scott Stanley is the CEO of Caring Hands Caregivers, and a member of the Neursantys Advisory Board. The authors report no other conflicts of interest in this work.

Figures

Figure 1
Figure 1
Phybrata sensor attached to the mastoid using an adhesive patch.
Figure 2
Figure 2
Sample eyes open (Eo) and eyes closed (Ec) x (anterior-posterior, AP), y (vertical), z (medial-lateral, ML) phybrata time series data for participants (a) with no reported fall history (b) reporting a single fall in the past 6 months (c) reporting multiple falls in the past 6 months.
Figure 3
Figure 3
Sample eyes open (Eo) and eyes closed (Ec) AP/ML phybrata spatial scatter plots and phybrata powers for participants (a) with no reported fall history (b) reporting a single fall in the past 6 months (c) reporting multiple falls in the past 6 months.
Figure 4
Figure 4
Box plots showing distributions of 4 phybrata metrics for (a) 329 participants with no reported falls and 187 participants with one or more reported falls (b) 230 female participants and 99 male participants with no reported falls (c) 104 female participants and 83 male participants with one or more reported falls.
Figure 5
Figure 5
ROC curves for 4 phybrata metrics used for the classification of falls history for all 516 participants.
Figure 6
Figure 6
Phybrata sensory reweighting plots for 20 lowest fall risk participants, 20 threshold low/high fall risk participants, and 20 highest fall risk participants (a) Eo (b) Ec.
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Florence CS, Bergen G, Atherly A, Burns E, Stevens J, Drake C. The medical costs of fatal falls and fall injuries in older adults. J Am Geriatr Soc. 2018;66(4):693–698. doi: 10.1111/jgs.15304 - DOI - PMC - PubMed
    1. Agrawal Y, Pineault KG, Semenov YR. Health-related quality of life and economic burden of vestibular loss in older adults. Laryngoscope Investig Otolaryngol. 2017;3(1):8–15. doi: 10.1002/lio2.129 - DOI - PMC - PubMed
    1. Roman-Liu D. Age-related changes in the range and velocity of postural sway. Arch Gerontol Geriatr. 2018;77:68–80. doi: 10.1016/j.archger.2018.04.007 - DOI - PubMed
    1. Hignett S, Masud T. A review of environmental hazards associated with inpatient falls. Ergonomics. 2006;49(5–6):605–616. doi: 10.1080/00140130600568949 - DOI - PubMed
    1. Davis LE. Dizziness in elderly men. J Am Geriatr Soc. 1994;42(11):1184–1188. doi: 10.1111/j.1532-5415.1994.tb06986.x - DOI - PubMed

LinkOut - more resources