To determine whether orthostatic hypotension (OH) impacts cognition in Parkinson disease (PD) over time as measured by Montreal Cognitive Assessment (MoCA), and whether cognition differs between symptomatic (sOH) and asymptomatic OH (aOH) patients.

Autonomic nervous system dysfunction causing OH affects up to half of PD patients¹. OH can lead to many symptoms including cognitive disturbances^2-4. OH can also be asymptomatic, and may cause transient cognitive decline without overt symptoms^5-8. Limited studies suggest that aOH and sOH PD patients have similar ambulatory and functional capacity, falls, and healthcare utilization^{9, 10}, but it remains unknown whether cognition differs between these groups. A better understanding of the association between OH and cognition is needed to guide therapeutic decision-making.  

Baseline and one follow-up visit data (mean follow-up duration= 4.2 years) was retrospectively obtained from our IRB-approved database.18 OH- and 18 OH+ (9 aOH, 9 sOH) PD patients matched for age, sex, education, disease duration, Hoehn and Yahr stage, and follow-up interval were identified. MoCA scores at baseline and final follow-up visits were compared between OH- and OH+, and sOH and aOH groups using repeated measures analysis of variance.  

MoCA scores increased at follow-up for OH- patients (baseline 24.8, follow-up 26.1), but decreased for OH+ patients (25.1, 23.5), showing that OH had a deteriorating impact on MoCA over time (p=0.025). Within the OH+ group, disease duration was longer in sOH compared to aOH (p=0.004). There was no difference in MoCA change between sOH and aOH (p=0.51), and no significant group and time interaction (p=0.56). There were no demographic differences between sOH and aOH groups.

Presence of OH was associated with clinically and statistically significant cognitive decline over time, independent of orthostatic symptoms. Larger studies are warranted to clarify how OH contributes to longitudinal cognitive decline, and whether treating OH has beneficial effects on cognition.