Association Between Orthostatic Hypotension and Dementia in Patients With Parkinson Disease and Multiple System Atrophy.

early OH, but not its symptom severity, increases the risk of cognitive impairment in patients with PD and MSA. OH is not associated to more extensive Lewy, amyloid-β, tau, Alzheimer's or cerebrovascular pathologies. It is likely that OH contributes to cognitive impairment in patients with PD and MSA by hypoxia-induced non-specific neurodegeneration. Further research should evaluate whether improving brain perfusion by treating OH may modify the risk of dementia in these conditions.