Effect of Visit-to-Visit Blood Pressure Variability on Cognitive and Functional Decline in Mild to Moderate Alzheimer’s Disease
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BACKGROUND: Visit-to-visit blood pressure (BP) variability (VVV) is increasingly recognized as a marker of cardiovascular risk. Although implicated in cognitive decline, few studies are currently available assessing its effects on established dementia. OBJECTIVE: To investigate if VVV is associated with one-year rate of decline in measures of cognition and function in patients with mild to moderate Alzheimer's disease (AD) in the Doxycycline And Rifampicin for Alzheimer's Disease study. METHODS: Patients were included if ≥3 BP readings were available (n = 392). VVV was defined using different approaches including the coefficient of variation (CV) in BP readings between visits. Outcomes included rates of decline in the Standardized Alzheimer's Disease Assessment Scale-Cognitive Subscale (SADAS-cog), Standardized MMSE, Clinical Dementia Rating Scale, the Quick Mild Cognitive Impairment screen and the Lawton-Brody activities of daily living (ADL) scale. RESULTS: Half of the patients (196/392) had a ≥4-point decline in the SADAS-cog over one-year. Using this cut-off, there were no statistically significant associations between any measures of VVV, for systolic or diastolic BP, with and without adjustment for potential confounders including treatment allocation, history of hypertension and use of anti-hypertensive and cognitive enhancing medications. Multiple regression models examining the association between systolic BP CV by quartile and decline over one-year likewise showed no clinically significant effects, apart from a U-shaped pattern of ADL decline of borderline clinical significance.∥Conclusions: This observational study does not support recent research showing that VVV predicts cognitive decline in AD. Further studies are needed to clarify its effects on ADL in AD.