Abstract
Orthostatic blood pressure (BP) dysregulation can impair cerebral blood perfusion and cognition. Water intake prevents syncope caused by orthostatic hypotension (OHypo) and improves orthostatic tolerance. However, research on scheduled water intake's effect on the association between OHypo and cognition is limited. This study aimed to investigate the impact of scheduled water intake on orthostatic BP dysregulation and mild cognitive impairment (MCI). This cross-sectional study was conducted in rural Fuxin, Liaoning Province, China, using cohort data. Water intake patterns were self-reported, and orthostatic BP was measured. MCI was assessed with the Chinese version of the Montreal Cognitive Assessment-Basic (MoCA-BC).Latent class mixed models were applied to identify systolic BP trajectory patterns. Logistic regression was used to examine the association between orthostatic BP abnormality and MCI, adjusting for potential confounders and including an interaction term for orthostatic BP abnormality and water intake regularity. Linear regression was used to analyze the relationship between orthostatic BP abnormality and total MoCA-BC score. Subgroup analyses were conducted based on age and water intake regularity. The study included 1576 participants: 1236 (78.4%) had normal recovery, 234 (14.8%) had delayed recovery, 36 (2.3%) had OHypo, and 70 (4.5%) had orthostatic hypertension. The average age was 63.2 ± 7.7 years, with a daily water intake of 1612.5 ± 978.8 ml; 1055 (66.9%) were female. Unscheduled water intake significantly interacted with OHypo on MCI (OR 5.82; 95% CI 1.17-35.34; P = 0.039). After adjusting for confounders, scheduled water intake was associated with a lower OR of MCI in those with OHypo (OR 0.11; 95% CI 0.02-0.44; P = 0.003), while unscheduled water intake showed no significant association (OR 0.99; 95% CI 0.41-2.57; P = 0.985). Scheduled water intake is linked to a lower risk of MCI in individuals with OHypo, suggesting a protective role. Promoting scheduled water intake might be inversely associated with MCI in OHypo patients. Further longitudinal studies are needed to confirm these findings and understand the mechanisms involved.