Objective: This study manipulated the imaging modality to illustrate the physiology of cerebral flow with OH in PD (PD+OH).

Background: Orthostatic hypotension (OH) may antedate Parkinson’s disease (PD) or be found in early stages of the disease. OH may induce a PD brain to chronic hypotensive insults. 18F-Florbetaben (18F-FBB) tracer has a high first-pass influx rate and can be used with positron emission tomography (PET) as a surrogate marker for early- and late-phase evaluation of cerebral perfusion and cerebral amyloidosis, respectively. In this study, we evaluated whether 18F-FBB uptake in the early- and late-phases of PD was related to OH.

Method: A group of 73 early-stage PD patients was evaluated with a head-up tilt-test and 18F-FBB PET imaging. The cognitive status was assessed by a comprehensive battery of neuropsychological screening tests. PET images were normalized, and both early- and late-phase standardized uptake value ratios (SUVRs) of pre-specified regions were obtained. The associations between regional SUVRs and OH and cognitive status were analyzed.

Results: Twenty (27.4%) participants had OH. Thirteen (17.8%) patients were interpreted as having amyloid pathology based on regional 18F-FBB uptake. Early-phase SUVRs were higher in specific brain regions of PD+OH patients than patients without OH. However, SUVR values of late-phase did not differ between the groups. Amyloid-positivity was not associated with early-phase perfusion between the groups. The early-phase SUVRs was not influenced by amyloid burden or by interaction between amyloid and orthostatic hypotension. Cognitive functions were not disparate when PD+OH patients were contrasted with non-OH patients in this study.

Conclusion: Cerebral blood flow is compensated to preserve functions in early PD+OH.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/paradoxical-cerebral-hyperperfusion-in-parkinsons-disease-with-orthostatic-hypotension/