Objective: Assessment of cardiovascular (CV) dysfunction, its association with motor symptoms of Parkinson's disease (PD) and dopaminergic therapy.

Methods: The study included 252 patients with Hoehn and Yahr stage I-III PD. All patients were assessed using a survey of symptoms of orthostatic intolerance (OI), an orthostatic test, UPDRS II-IV, a Sch&En daily activity score, and a Mini-Mental State Examination (MMSE). A heart rate variability (HRV) test was performed on 31 patients and 10 control subjects of comparable age.

Results: OI symptoms were detected in 35.3% of patients, orthostatic hypotension in 5.8%, and lying hypertension in 34%. The HRV indices (SDNN, TP, VLF, and LF) were decreased in all patients versus the controls (p<0.0001); no normal increase in sympathetic effects occurred with the orthostatic test. The PD stage was associated with OI symptoms (p=0.003), a decrease in the total HRV power (rS=-0.357; p=0.049), an increase in lying hypertension and heart rate, and a decrease in changes in heart rate during the orthostatic test. Patients with OI symptoms had longer PD history and worse Sch&En and UPDRS scores (hypokinesia, posture, resistance, dyskinesia scores). Significant negative correlations of HRV were identified with the same motor indices: UPDRS II and III, impaired gait, posture, stiffness, and rigidity. Resting tremor or action tremor had no association with HRV and OI. The use of dopaminergic drugs (levodopa, amantadines, dopamine receptor agonists) was associated with lower systemic blood pressure and OI symptoms but did not aggravate orthostatic responses and HRV.

Conclusions: Obtained data indicate the presence in patients with the initial stages of PD of autonomic CV dysfunction, closely related to the motor (especially walking and postural balance) symptoms of PD by a single neurodegenerative process covering both central and peripheral structures of the autonomic nervous system.