Association of Ankle Brachial Index and Cognitive Function in Elderly Hypertensive Patients: A 2-Year Longitudinal Study

Background: Ankle brachial index (ABI) is widely used to evaluate peripheral artery disease and atherosclerosis. Given the recognized links between atherosclerosis and cognitive impairment, this study was designed to evaluate the association between ABI and cognitive function in elderly hypertensive patients. Methods: A total of 408 elderly hypertensive patients from two hospitals were included and followed up for two years in 3 groups according to the ABI tertiles (Low ABI, ABI < 1.07 (n = 140); Intermediate ABI 1.07-1.12 (n = 136), High ABI > 1.12 (n = 132)). Cognitive function was assessed by the Mini-Mental State Examination (MMSE). Multiple analyses were used to evaluate the connection between ABI and cognitive function. Subgroup analyses along with interaction tests were done to see if this link was consistent. The analysis of covariance (ANCOVA) was used to compare the cognitive decline among 3 groups during a 2-year follow-up adjusted for related confounding factors. Results: ABI was independently correlated with MMSE score (B: 9.844, 95% CI: 7.088–12.600, P<0.001), while the blood pressure-related parameters and brachial-ankle pulse wave velocity (BaPWV) were not. The frequencies of cognitive impairment decreased among the 3 groups (22.1%, 8.1%, 3.0%, P < 0.001). Compared with high ABI group, low ABI group was associated with a higher prevalence of cognitive impairment (OR: 5.980, 95% CI: 1.966-18.187, p = 0.015). ABI was negatively associated with cognitive impairment (OR: 0.057, 95% CI: 0.014-0.787, p = 0.026), and this association was more pronounced in the old-old subgroup. The MMSE score decline value decreased among 3 groups overall (F = 9.619, P < 0.001) and old-old (F = 5.333, p = 0.006) hypertensive patients over a 2-year follow-up, but not in the young-old patients (F = 2.345, p = 0.098). Conclusions: ABI is associated with cognitive impairment and cognitive function decline in elderly hypertensive patients, superior to the blood pressure-related parameters and BaPWV. Besides, the association is stronger in the old-old than in the young-old.