Most folks tap away at their smartphone for fun, communication, or information.
But such tapping may also help them track the progress of a rare degenerative brain disease, researchers say.
Five simple smartphone-measured tests of movement control can provide quick and regular insight into the motor function of someone with Huntington’s disease, according to a groundbreaking study published June 9 in the journal Brain. These app-based tests—focused on balance, finger tapping, and involuntary movements—are used to produce the Huntington’s Disease Digital Motor Score (HDDMS), a digital tool that may dramatically improve how clinicians detect and monitor disease progression.
What Is the HD Digital Motor Score (HDDMS)?
The HDDMS is a composite score designed to evaluate motor symptoms in people with Huntington’s disease (HD) using data collected via a smartphone. Developed by researchers led by Louis-Solal Gibion, Ph.D., from F. Hoffmann-La Roche Ltd in Basel, Switzerland, the score draws on smartphone sensors to measure key areas of motor control, including balance, chorea (involuntary movements), speeded tapping, and gait.
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Using built-in sensors like accelerometers and gyroscopes, the smartphone captures data during simple motor tasks performed at home. This data is distilled into the HDDMS using factor analysis and weighted scoring to reflect disease severity. The entire process takes just five minutes, making it convenient and scalable for widespread use.
A Smart Way to Track a Complex Disease
“Incorporating the HDDMS in clinical trials will help to give clearer answers about whether a potential treatment is working, with fewer participants or shorter lead times than conventional measures,” said Ed Wild, professor of neurology at University College London’s Huntington’s Disease Center.
“What’s more, the fact that the HDDMS is evaluated in a five-minute assessment in people’s homes makes it convenient and potentially more meaningful than in-clinic measures of motor impairment,” he added in a news release.
This remote monitoring model represents a shift toward digital biomarkers—objective, sensor-based data that offer real-time insights into a patient’s condition outside of clinical settings.
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Why It Matters
Huntington’s disease is a genetic neurological disorder that causes nerve cells in parts of the brain to break down and die. It primarily affects areas responsible for movement, leading to uncontrollable, dance-like motions and distorted postures. Symptoms can worsen under stress or distraction, and there is currently no cure.
Because of the disease’s slow, progressive nature and its variability across individuals, it has traditionally been challenging to measure subtle shifts in motor function. Accurate tracking is crucial now more than ever, as promising new treatments move into clinical trials.
Development and Validation of the HDDMS
The HDDMS was created using data from more than 1,000 individuals across four separate clinical studies. This extensive dataset allowed researchers to identify the movement characteristics most predictive of disease progression and determine how these could be captured using smartphone-based tests.
In clinical validation, the score demonstrated:
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High reliability (intraclass correlation coefficient >0.95)
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Strong correlation with the gold-standard composite Unified Huntington’s Disease Rating Scale (cUHDRS) (r = -0.5)
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Greater sensitivity to change, detecting disease progression in 20 weeks compared to 68 weeks for the cUHDRS
These findings indicate that the HDDMS is approximately twice as accurate at detecting changes in motor function as conventional methods.
A New Era for Clinical Trials
The enhanced sensitivity of the HDDMS could make clinical trials for Huntington’s disease more efficient by:
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Requiring fewer participants
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Shortening trial durations
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Enabling early-phase insights into treatment efficacy
“More sensitive tools to measure disease progression are particularly valuable in rare diseases like Huntington’s disease,” Wild noted. “The fewer people there are who can possibly participate in clinical trials, the more important it becomes to minimize trial burden and size.”
Limitations and Future Outlook
While the results are highly promising, researchers caution that more studies are needed to confirm the HDDMS’s ability to predict long-term functional decline. The current data is robust for short-to-medium-term monitoring, but continued observation will help clarify how well the tool can inform long-term care planning.
Additionally, since several authors disclosed financial ties to F. Hoffmann-La Roche and Ionis Pharmaceuticals, and the study was partially funded by these companies, transparency and further independent validation will be key to widespread adoption.
Final Thoughts
As Huntington’s disease continues to challenge patients, caregivers, and researchers, tools like the HDDMS offer hope not only for better treatments, but also for better ways to track those treatments’ effects. By moving assessments out of the clinic and into the comfort of patients’ homes, the HDDMS provides a new level of accessibility, sensitivity, and convenience in disease monitoring.
The ability to detect even small changes in symptoms could transform both care and research, ushering in a new era of personalized, data-driven support for people living with HD.
