Decreased baroreflex sensitivity in Parkinson's disease is associated with orthostatic hypotension

Background: Autonomic dysfunction is a substantial part of extrapyramidal diseases, including Parkinson's disease (PD). Baroreflex is an important determinant of short-term blood pressure regulation and cardiovascular variability. Impaired baroreflex sensitivity (BRS) in PD has been a subject of investigation in several studies, however the relationship between BRS and orthostatic hypotension (OH) is still poorly understood.

Objective: To compare the BRS of Parkinson's disease patients with those of an age-matched control population, and to determine BRS association with blood pressure, orthostatic hypotension and antiparkinson treatment.

Patients and methods: The study included 52 patients with Parkinson's disease and 52 controls. We assessed autonomic dysfunction with a Finometer device using the method of spontaneous fluctuations of blood pressure (BP) and the R-R interval in time domain, expressed as baroreflex sensitivity. Supine and standing blood pressure were measured under standard conditions.

Results: BRS values were significantly lower in the PD group as compared to the control group: 4.0±2.0 vs. 6.4±3.8ms/mmHg (p=0.001). We determined a significant correlation between decreased BRS values and increased systolic BP (p=0.003) as well as between decreased BRS values and orthostatic hypotension (OH), in the PD group (p=0.048). Moreover, patients with PD and OH had significantly lower BRS as compared with patients with PD without OH (3.2±2 versus 4.5±2, p=0.045). We also determined that BRS values were significantly lower in the PD population treated with LDOPA+COMTI as compared to the LDOPA+COMTI untreated patients (3.0±1.5 vs. 4.8±2.0, p<0.001).

Conclusion: BRS was significantly lower in the PD group, supine hypertension and orthostatic hypotension was strongly associated with low BRS. We determined for the first time that orthostatic hypotension strongly correlates with decreased baroreflex sensitivity in PD patients. Moreover, orthostatic hypotension was associated with low BRS not only qualitatively but also quantitatively. We also revealed a strong association between LDOPA+COMTI therapy and decreased BRS in the literature for the first time.