Associations of Orthostatic Hypotension and Orthostatic Intolerance with Domain-Specific Cognitive Decline in Patients with Early Parkinson Disease: An 8-Year Follow-up

Objective Although orthostatic hypotension (OH) and orthostatic intolerance (OI) are prevalent in patients with Parkinson disease (PD), it remains unclear how these conditions primarily affect the trajectory of decline in specific cognitive domains. This study aimed to explore the effects of OH and OI on longitudinal domain-specific cognitive changes in patients with PD. Design An 8-year follow-up of the Parkinson Progression Markers Initiative cohort study. Setting and Participants A total of 403 patients with early, untreated PD and 195 matched healthy controls were included. They were classified into OH, OI, and normal groups. OH was defined according to the international consensus, and OI was defined as the presence of orthostatic symptoms without meeting the criteria for OH. Methods The patients underwent detailed neuropsychological testing annually for up to 8 years of follow-up. Linear mixed effects models were used to investigate the associations between OH, OI, and longitudinal cognitive changes. Results The prevalence of both OH and OI in patients with PD was significantly higher than that in controls (13.4% vs 7.2%, P = .002, for OH, and 29.3% vs 14.4%, P < .001, for OI). The OH group in patients with PD showed a faster decline in Letter-Number Sequencing (LNS) (β = −0.11, 95% CI −0.20 to −0.02, t = −2.44, P = .015) and Semantic Fluency Test (SFT) (β = −0.44, 95% CI –0.81 to −0.08, t = −2.42, P = .016) scores than the normal group. Similarly, the OI group showed a steeper decline in LNS (β = −0.08, 95% CI –0.14 to −0.01, t = −2.20, P = .028) and SFT (β = −0.36, 95% CI –0.63 to −0.08, t = −2.55, P = .011) scores compared to the normal group. There were no significant longitudinal changes in the other neuropsychological test scores between the groups. Conclusions and Implications Both OH and OI may be associated with a faster decline in executive function among cognitive domains of patients with PD. These findings may highlight the potential importance of orthostatic blood pressure control in PD patients with OH and even those with orthostatic symptoms without OH.