Heart Rate Variability in evaluation of autonomic dysfunction in idiopathic REM-sleep behaviour disorder

Area of Science:

• Neurology
• Sleep Medicine
• Cardiology

Background:

• Idiopathic REM sleep behaviour disorder (iRBD) often precedes alpha-synucleinopathies.
• Autonomic dysfunction may be an early indicator of alpha-synucleinopathy.
• Heart Rate Variability (HRV) offers a potential objective measure of autonomic dysfunction, obtainable from v-PSG.

Purpose of the Study:

• To assess dysautonomia in iRBD patients using HRV during sleep and wakefulness.
• To correlate HRV parameters with autonomic dysfunction measured by the Non-Motor Symptoms Scale (NMSS).
• To determine optimal HRV cut-off values for predicting dysautonomia.

Main Methods:

• Subjects with suspected RBD underwent v-PSG for diagnosis.
• HRV was analyzed from v-PSG recordings.
• Correlation and regression analyses were used to evaluate HRV, NMSS scores, and confounding variables.

Main Results:

• Twenty-nine iRBD subjects were diagnosed; 83% showed signs of prodromal Parkinson's Disease (pPD).
• A significant inverse correlation was found between NMSS score and log low-frequency (LF) HRV during wakefulness (r = -0.59, p = 0.001).
• Log LF HRV during wakefulness showed potential for predicting dysautonomia (AUC 0.74), but HRV did not predict iRBD presence, and results were confounded by age, gender, and sleep apnea.

Conclusions:

• HRV from v-PSG was not confirmed as a reliable predictor of questionnaire-assessed dysautonomia in iRBD patients.
• Confounding factors significantly impacted HRV predictability in this cohort.
• Further research is needed to clarify the role of HRV in iRBD and alpha-synucleinopathies.