Discussion/ConclusionsAssociations

Discussion/ConclusionsAssociations between cerebral blood flow and cognition have been reported in high-grade asymptomatic carotid stenosis, but prior studies have only partially quantified the nature of the cognition-hemodynamic relationship. In the current study, we used an easily attainable hemodynamic measure − MFV by TCD − to show that reduced blood flow has a linear relationship to cognitive impairment in the setting of asymptomatic high-grade carotid artery disease, but only below an identifiable flow velocity threshold. Cognitive function, as measured by a composite Z-score on a standard neurocognitive test battery, declined in a linear fashion below a threshold of 45cm/s. This threshold is in the low normal range for patients from 60 to 80 years of age [18]. In contrast, cognition remained constant when flow velocities were >45 cm/s. The relationship did not hold for every individual. As illustrated in Figure ​Figure1,1, 9 of the patients whose MFV was