High norepinephrinergic orthostatic hypotension in early Parkinson's disease.

INTRODUCTION: Plasma norepinephrine concentration reflects lesions causing OH. We investigate whether patients with high norepinephrinergic orthostatic hypotension (OH) whose supine plasma norepinephrine concentration (NEsupine ) is above the mean value in all patients with Parkinson's disease (PD) have central sympathetic denervation.

METHODS: We analyzed data from 110 non-demented patients with early de novo PD who underwent cardiovascular examinations. We divided the patients into three groups according to the presence or absence of orthostatic hypotension and NEsupine : patients without OH, patients with OH+high NEsupine , and patients with OH+low NEsupine .

RESULTS: The mean NEsupine in all patients was 251.6 pg/ml. Twelve patients (10.9%) had OH+high NEsupine (≥251.6 pg/ml), and 45 patients (40.9%) had OH+low NEsupine (<251.6 pg/ml). OH was more pronounced in patients with OH+high NEsupine than in those with OH+low NEsupine (p = 0.024). Vasopressin release and percent increase of NE after orthostatic stress were well preserved in patients with OH+low NEsupine , but not in patients with OH+high NEsupine . Cognition was lower in patients with OH+high NEsupine than in patients with OH+low NEsupine (p = 0.019) and was associated with vasopressin release during orthostatic stress on multiple regression analysis. The degree of cardiac sympathetic denervation did not differ between two groups with OH.

CONCLUSIONS: Patient with PD and high norepinephrinergic OH are a subset of patients who have early cognitive decline and impaired vasopressin release. Vasopressin release after orthostatic stress was closely related to global cognition in PD.