Cardiovascular autonomic dysfunction in Parkinson's disease: associations with disease severity and the modulatory role of dopaminergic therapy

Abstract Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by both motor and non-motor symptoms, with autonomic dysfunction significantly impacting patients' quality of life. Despite its recognized importance, comprehensive evaluation of autonomic dysfunction in PD remains limited. To assess cardiovascular autonomic dysfunction in PD, explore its association with disease severity, and examine the modulatory effects of dopaminergic therapy. A cross-sectional study was conducted involving 60 PD patients and 30 age- and sex-matched healthy controls. Autonomic function was evaluated using standardized cardiovascular tests, including deep breathing, the Valsalva maneuver, and head-up tilt. Heart rate variability, baroreflex sensitivity, and orthostatic blood pressure responses were measured. Parkinson's disease patients were evaluated in both dopaminergic medication ON and OFF states. Correlations between autonomic parameters and disease severity were analyzed. Parkinson's disease patients demonstrated significant autonomic impairment compared to controls (p < 0.001). Standard deviation of NN intervals (SDNN) (21.3 ± 8.7 vs. 32.5 ± 10.2 ms), baroreflex sensitivity (4.2 ± 1.8 vs. 7.1 ± 2.3 ms/mmHg), and heart rate response to deep breathing (8.3 ± 3.2 vs. 13.7 ± 4.1 bpm) were reduced, while systolic blood pressure drop on tilt increased (22.5 ± 12.8 vs. 8.3 ± 5.7 mmHg). Autonomic impairment correlated with disease severity. Dopaminergic medication showed modest but significant improvements in heart rate variability (p = 0.032), baroreflex sensitivity (p = 0.041), and orthostatic response (p = 0.025). Parkinson's disease patients exhibit marked cardiovascular autonomic dysfunction correlating with disease severity. The modest modulatory effects of dopaminergic medication on autonomic parameters suggest complex dopaminergic-autonomic interactions and supports autonomic parameters as potential markers of disease progression.