Reduced central sympathetic activity in Parkinson's disease

Objective With a combination of different sympathetic tests, we aimed to elucidate whether impairment of sympathetic function in Parkinson's disease (PD) is the consequence of a central or peripheral efferent dysfunction. Methods Thirty‐five patients with early‐to‐intermediate PD (median age: 63 years; IQR: 57–67 years; disease duration 1–9 years, 15 women) and 20 age‐ and sex‐matched healthy controls (median age: 64.5 years; IQR: 58–68 years; 10 women) were recruited. Autonomic testing was performed in two subgroups and included the assessment of resting cardiovascular parameters, postprandial hypotension (PPH), orthostatic hypotension (OH), and vasoconstriction induced by intradermal microdialysis with different concentrations of norepinephrine (NE; 10–5; 10–6; 10–7; 10–8) and by cold through forehead cooling. We also used sympathetic multiunit microneurography (muscle sympathetic nerve activity; MSNA; burst frequency (BF): bursts per minute; burst incidence (BI): bursts per 100 heart beats) and evaluated the presence of phosphorylated α‐synuclein deposits in skin innervation in biopsies from the thighs by immunohistohemistry. Results Diastolic blood pressure was higher in the PD group at rest (p