Ankle brachial index, MRI markers and cognition: The Epidemiology of Dementia in Singapore study.

BACKGROUND AND AIMS

Previous studies showed an independent association of low ankle-brachial index (ABI) with cognitive impairment. However, the association between low ABI and cognition in the presence of both cerebrovascular disease (CeVD) and neurodegeneration is lacking. We aimed at investigating a) the association of low ABI with markers of CeVD and cortical thickness, and b) whether the association of low ABI with cognition is influenced by these markers.

METHODS

Data was drawn from the Epidemiology of Dementia In Singapore (EDIS) study where all participants (n = 832) underwent neuropsychological tests and 3T brain magnetic resonance imaging (MRI) to assess CeVD markers as well as cortical thicknesses. Cognitive function was expressed as a global composite z-score and domain-specific z-scores of a comprehensive neuropsychological battery.

RESULTS

Multivariate analyses showed low ABI to be independently associated with intracranial stenosis [odds ratios (OR): 1.51; 95% confidence interval (CI):1.23-1.87] and lacunar infarcts [OR: 1.29; 95% CI: 1.06-1.57]. A low ABI was also independently associated with smaller cortical thickness globally [β: 0.09; 95% CI: 0.27-0.16] as well as with the limbic [β: 0.10; 95% CI: 0.03-0.17], temporal [β: 0.09; 95% CI: 0.02-0.15], parietal [β: 0.08; 95% CI: 0.02-0.15], and occipital [β: 0.09; 95% CI: 0.03-0.16] lobes. Low ABI was associated with worse performance in verbal memory [β: 0.06; 95% CI: 0.01-0.12], which became attenuated in the presence of MRI markers.

CONCLUSIONS

A low ABI is associated with MRI markers, and affects cognition in the presence of CeVD and neurodegeneration. Atherosclerosis should be targeted as a potentially modifiable risk factor to prevent cognitive disorders.