Wearable heart monitor shows distinct signal in Parkinson's disease, small study finds

A case-control study using a wearable ECG device found that several measures of heart rate variability were reduced in people with Parkinson's disease, and that one measure, low-frequency power, tracked tremor severity and correlated with brain volume on MRI. The pattern is different from the Alzheimer's-linked HRV changes reported earlier in this section, and the authors say it needs testing in far larger groups before it could serve as any kind of diagnostic tool.

A small case-control study has found that heart rate variability measured with a wearable electrocardiogram device differs between people with Parkinson's disease and healthy controls, and that one measure, low-frequency (LF) power, tracked the severity of tremor and correlated with the volume of gray matter in the cerebellum and thalamus on MRI. The findings were published in Frontiers in Aging Neuroscience on May 12, 2025, by researchers at Yonsei University Wonju College of Medicine in South Korea.

The study prospectively enrolled 17 healthy controls and 20 people with Parkinson's disease, who wore an ECG device continuously for up to 72 hours. After adjusting for age and sex, several HRV measures, including the standard deviation of heart-to-heart intervals, the standard deviation of heart rate, and LF power, were associated with a Parkinson's diagnosis. Of these, only LF power also correlated with a clinical feature: it rose and fell with tremor sub-scores on a standard Parkinson's rating scale (r = 0.500, p = 0.035).

When the researchers compared HRV to brain MRI scans, LF power was negatively correlated with gray matter volume in the left cerebellum (r = -0.598, p = 0.024) and right cerebellum (r = -0.693, p = 0.006), and also with thalamic volume, after adjusting for age, sex, and total brain size. The authors describe LF power as a possible biomarker of tremor-related pathology in Parkinson's disease and describe long-term wearable ECG monitoring as a "promising tool" worth further study, not a diagnostic test.

Outside researchers have reported HRV changes in Parkinson's disease before, including in ambulatory ECG studies dating back two decades, but results linking HRV to specific brain regions using modern wearable devices remain few and, by the authors' own account, this is one small step in that direction.

The study adds to a body of work treating the autonomic nervous system, not just the brain, as a source of measurable signal in movement disorders, but the authors themselves frame it as hypothesis-generating rather than conclusive.