Cognitive Decline Associated with Longitudinal Changes in 24‐h Ambulatory Blood Pressure Variability

Background Cognitive decline has been associated with variability in blood pressure (BP). However, whether the increment of the BP variability during follow‐up precedes cognitive decline remains undocumented. We aimed this study to investigate cognitive decline in relation to longitudinal changes in 24‐h reading‐to‐reading BP variability. Methods We conducted an observational longitudinal study that included 717 dementia‐free participants from the Maracaibo Aging Study who underwent follow‐up assessment in both 24‐h ambulatory BP monitoring and cognitive tests between 1998 and 2015. Cognitive domains consisted of selective reminding tests (total, long‐term, short‐term, and recognition memory) and the Mini‐Mental State Examination (MMSE). Cognitive decline was a longitudinal decrease in cognitive scores. Participants underwent 24‐h ambulatory BP monitoring between 2‐4 times – with at least one‐year interval. Systolic and diastolic BP variability was studied during 24‐h and divided into daytime (from 06h00 to 23h00), and nighttime (23h00 to 06h00) periods. To account for BP level, we used variability independent of the mean (VIM) to compute systolic and diastolic BP variability. Other measures of BP variability included the nocturnal BP drop in comparison to the daytime BP level, which was estimated as the night‐to‐day ratio. Statistics included multivariate linear regression mixed models. Results Overall, the mean age was 65.6±7.36 years old and 66.5% (n = 447) of the participants were women. In mixed models, a decline in all memory domains was associated with greater variability in the 24‐h, daytime, and nighttime systolic BP during follow‐up, with an estimated decline in cognitive scores ranging from ‐0.2 to ‐0.04 points per unit increase in VIM systolic BP during follow‐up (P values ranged from 0.022 to 0.003). Decline in total, short‐term, and MMSE memory domains was associated with greater 24‐h and daytime diastolic BP variability (P≤0.015). A lower night‐to‐day dipping ratio during follow‐up increased the risk of cognitive decline, with a ‐5.8 to ‐1.6 decline in long‐term memory and MMSE scores; respectively (P≤0.037). Conclusions Cognitive decline associates with greater reading‐to‐reading 24‐h BP variability and lower falls in nocturnal BP over time. These findings might be indicative of deteriorated regulatory mechanisms to maintain steady BP levels as individuals age.