Nocturnal heart rate variability in Parkinson's disease: associations with autonomic dysfunction, cognitive function, and mood symptoms

Introduction Heart Rate Variability (HRV) analysis reflects beat-to-beat fluctuations in RR intervals, serving as a method to non-invasively monitor sympatho-vagal balance during sleep. The primary aim of this study is to investigate nocturnal HRV in Parkinson's Disease (PD). In addition, we explore its association with various non-motor symptoms. Methods In 36 participants with PD and 20 healthy controls (HC), frequency-domain HRV analysis of polysomnography-derived electrocardiogram data was conducted to derive low-frequency power (LF), high-frequency power (HF), and LF/HF ratio in NREM and REM sleep. In PD subjects, Spearman correlations were determined between HRV variables and the MDS-UPDRS sub-scores for autonomic symptoms (1.10–1.12) and mood (1.3, 1.4), the Pittsburgh Sleep Quality Index (PSQI), the Beck Depression Inventory (BDI), and a comprehensive neurocognitive battery. Results Individuals with PD demonstrated lower LF (NREM p = 0.037, REM p = 0.007), lower LF/HF (NREM p = 0.046, REM p = 0.0106), and higher HF (NREM p = 0.037, REM p = 0.008) compared to HC subjects. In PD subjects, executive function and processing speed were negatively correlated with LF and LF/HF (p = 0.03; p = 0.033) and positively correlated with HF ( p = 0.029; p = 0.033) during NREM. Greater severity of lightheadedness and urinary problems correlated with worse performance in multiple cognitive domains and higher BDI scores. Conclusion Our findings offer novel insight into the association between HRV and non-motor symptoms in PD. Individuals with PD have reduced sympathetic influence on HRV during sleep compared to HC. However, stronger parasympathetic influence correlates with better cognitive performance. Furthermore, subjective autonomic symptoms are correlated with poorer cognition and mood.