What question did this study set out to answer?

This research examines how cardiac autonomic dysfunction manifests across sleep stages in patients with alpha-synucleinopathies.

January 22, 2026BMJ Neurology Open0 citationsOpen Access

Exploring cardiac autonomic dysfunction in synucleinopathies with parkinsonism through awake–sleep stages: a possible connection to cardiovascular death

Q: What does this research mean for the field?

Patients with alpha-synucleinopathies show significantly reduced pNN50 during NREM sleep, indicating impaired nocturnal parasympathetic activity. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

NLNatlada LimotaiNeurological Institute of Thailand TSThapanee SomboonCleveland Sleep Research Center NSNarupat SuanprasertNeurological Institute of Thailand

Key Result

Patients with alpha-synucleinopathies showed significantly reduced pNN50 during NREM sleep (p=0.008), indicating impaired nocturnal parasympathetic activity.

Key Points

This research examines how cardiac autonomic dysfunction manifests across sleep stages in patients with alpha-synucleinopathies.
Retrospective analysis of 25 patients with alpha-synucleinopathies and 35 age-matched controls
Overnight polysomnography was conducted to collect sleep data
ECG segments from wakefulness, NREM, and REM sleep were analyzed for heart rate variability.
Significant reduction in heart rate variability indices in patients compared to controls
Most notable differences in NREM sleep, with a pNN50 of 0.008
Absence of normal parasympathetic activity elevation during NREM sleep in patients with synucleinopathies.

Structured PICO

Population

60 adults, including 25 patients with alpha-synucleinopathies with parkinsonism (13 idiopathic Parkinson's disease, 10 multiple system atrophy, 2 dementia with Lewy bodies; mean age 67.4, 76% male) and 35 age-matched controls without parkinsonism (mean age 63.1, 45.7% male).

Outcome

Time- and frequency-domain heart rate variability (HRV) indices (SDNN, RMSSD, pNN50, LF, HF, LF/HF ratio) computed from 5-minute ECG segments during wakefulness, non-rapid eye movement (NREM), and rapid eye movement (REM) sleep.surrogate

Patients with alpha-synucleinopathies exhibit blunted nocturnal parasympathetic activity, particularly during NREM sleep, suggesting that sleep-stage-specific HRV could serve as a biomarker for autonomic dysfunction and cardiovascular risk.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

Introduction Alpha-synucleinopathies (ASs), including Parkinson’s disease, multiple system atrophy and dementia with Lewy bodies, are characterised by autonomic dysfunction that may predispose to cardiovascular events and sudden death. Heart rate variability (HRV) is a non-invasive marker of autonomic regulation, yet its modulation across sleep stages in ASs remains unclear. Methods We retrospectively analysed 25 patients with ASs and 35 age-matched controls who underwent overnight polysomnography between 2020 and 2023. 5 min ECG segments from wakefulness, non-rapid eye movement (NREM) and rapid eye movement (REM) sleep were used to compute time- and frequency-domain HRV indices. Statistical comparisons and multivariate models were adjusted for sex and REM sleep behaviour disorder. Results HRV indices, particularly percentage of successive RR intervals that differ by more than 50 milliseconds (pNN50) and root mean square of successive differences, were significantly reduced in ASs compared with controls. The most pronounced difference occurred during NREM sleep (pNN50, p=0.008), where controls exhibited normal parasympathetic elevation that was absent in ASs. Conclusion Patients with ASs demonstrate blunted nocturnal parasympathetic activity, most evident during NREM sleep. Sleep-stage-specific HRV analysis provides sensitive insights into cardiac autonomic dysfunction and may serve as a potential biomarker of disease severity and cardiovascular risk in synucleinopathies.

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