Objective: We aim to assess the relationship between neurogenic Orthostatic Hypotension (nOH) and general dysautonomia in an early motor PD cohort.

Background: Dysautonomia is a known complication of PD[1], and one of its manifestation is nOH, which is orthostatic hypotension (OH) characterized by a blunted HR increase in the presence of a drop in systolic blood pressure (SBP)[2]. Although a recent study did not show association between nOH and brain pathology in PD[3], nOH has been related to cortical atrophy in the same population [4]. In this context we aimed to explore if nOH was also related to general dysautonomia in PD.

Method: Subjects from PPMI database with baseline orthostatic vital signs and SCOPA-AUT scores, excluding sexual dysfunction, were selected. We excluded items related to sexual dysfunction due to non-response rate. Dysautonomia was measured using the SCOPA-AUT rating scale. OH was defined as a drop of ≥20mm Hg in SBP or ≥10 mm Hg in diastolic blood pressure (DBP) [5]. A cutoff of ΔHR/Δ-SBP < 0.5 was used to categorize presence of nOH[2]. Two different methods were used to explore our hypothesis. First, Student’s t-test was used to assess nOH’s association with increased SCOPA-AUT scores. A second more exhaustive method included a machine learning method in which two random forest regression models were used to predict SCOPA-AUT scores. A full model included orthostatic vital signs and demographics as predictors, and a control model that included only demographics. To determine whether vital sign changes impacted the outcomes, we compared the mean absolute errors of the scores between models.

Results: 679 subjects were included in the analysis. Subjects with nOH (n=56, mean age=67) were older than patients without it (n=623, mean age=61). Student’s t-test did not show significant differences between groups in total SCOPA-AUT scores (p=0.21) or its subsections. Random forest regression models showed no difference in mean absolute errors between models (p=0.13) for total SCOPA-AUT.

Conclusion: Orthostatic vital sign changes and nOH did not predict general dysautonomia using the SCOPA-AUT in this early motor PD cohort. Early longitudinal follow up of orthostatic vital signs and inclusion of other variables may help improve the model and predict clinical dysautonomia in PD.

References: 1. Merola A, Romagnolo A, Rosso M, Suri R, Berndt Z, Maule S, et al. Autonomic dysfunction in Parkinson’s disease: A prospective cohort study. Movement disorders : official journal of the Movement Disorder Society. 2018;33(3):391-7.

2. Norcliffe-Kaufmann L, Kaufmann H, Palma J-A, Shibao CA, Biaggioni I, Peltier AC, et al. Orthostatic heart rate changes in patients with autonomic failure caused by neurodegenerative synucleinopathies. Annals of Neurology. 2018;83(3):522-31.

3. Ruiz Barrio I, Miki Y, Jaunmuktane ZT, Warner T, De Pablo-Fernandez E. Association Between Orthostatic Hypotension and Dementia in Patients With Parkinson Disease and Multiple System Atrophy. Neurology. 2023;100(10):e998-e1008.

4. Pilotto A, Romagnolo A, Scalvini A, Masellis M, Shimo Y, Bonanni L, et al. Association of Orthostatic Hypotension With Cerebral Atrophy in Patients With Lewy Body Disorders. Neurology. 2021;97(8):e814-e24.

5. Freeman R, Wieling W, Axelrod FB, Benditt DG, Benarroch E, Biaggioni I, et al. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Clin Auton Res. 2011;21(2):69-72.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neurogenic-orthostatic-hypotension-is-not-associated-with-generalized-dysautonomia-in-early-motor-pd/