Analysis of heart rate response to sleep apnea events in patients with Parkinson’s disease

Degeneration of the autonomic nervous system is observed in the early stage of Parkinson’s Disease (PD). Because of this, early detection of PD may be possible by detecting abnormalities in autonomic nervous system activity. Although 27-60% of patients with PD have sleep apnea syndrome (SAS), sympathetic cardiac overdrive is observed in SAS patients, while degeneration of the sympathetic nervous system is observed in PD. These findings suggest it may be possible to differentiate patients with PD from patients with SAS using their autonomic nervous response. In this study, we analyzed and compared the heart rate response pattern to sleep apnea events in SAS patients to patterns in PD patients with SAS (PD + SAS). Twenty patients with SAS and 15 patients with PD + SAS underwent overnight polysomnography (PSG) at Toneyama National Hospital. Electrocardiography (ECG), SpO2, and airflow data were measured and used for analysis. Time series of participant’s instantaneous heart rate were calculated from ECG signals. The timing of sleep apnea events was calculated from airflow data. In addition, the (1) latency and (2) amplitude of participant’s heart rate response, area of (3) increasing and (4) decreasing heart rate responses, and (5) participant’s heart rate response during the early phase of SpO2 reduction were calculated for each heart rate response to sleep apnea events. Sleep apnea events were divided into two categories based on whether they were the first event in the consecutive series or not. Results found no statistically significant difference in heart rate response indices between patients with PD and PD + SAS for the first apnea event in a consecutive series. On the contrary, the amplitude and area of increasing heart rate responses as well as heart rate response during the early phase of SpO2 reduction were all statistically significantly lower in patients with PD + SAS than in patients with SAS for all the apnea events except the first one in the consecutive series. These results indicate the attenuation of the autonomic nervous system response to sleep apnea events in patients with PD.