Dissecting the Vascular-Cognitive Nexus: Energetic vs. Conventional Hemodynamic Parameters

ABSTRACT Background Blood flow measurements are being studied in relation to vascular health and cognitive function, but their role is unclear. Objective We investigated whether energetic hemodynamic parameters, such as aortic and carotid mean and pulsatile energy, and energy pulsatility index (PI), provide a more nuanced understanding of the vascular-cognitive link, as assessed by the Montreal Cognitive Assessment (MoCA), than conventional flow and flow PI. Methods Cognitive evaluation and hemodynamic measurements, including aortic and carotid pressure and flow waves, were performed on 1858 MoCA participants. Energy was calculated by integrating pressure time flow. An asymmetric bifurcation model was used to calculate aortic and carotid mean, pulsatile energy, and hemodynamic parameters across the interface. Results After adjusting for age, sex, education, depression score, heart rate, BMI, HDL-cholesterol, and glucose levels, energetic hemodynamic parameters were more associated with MoCA score than aortic and carotid flow and flow PI. In particular, carotid mean energy was most significantly positively associated with MoCA (standardized beta = 0.053, P = 0.0253) and energy PI was most significantly negatively associated (standardized beta = -0.093, P = 0.0002), surpassing conventional metrics like carotid PI. Aortic pressure reflection coefficient at the aorta-carotid bifurcation was positively correlated with mean carotid energy and weakly negatively correlated with PI. Aortic characteristic impedance positively correlated with carotid energy PI but not mean energy. Conclusion Our study shows that energetic hemodynamic parameters, particularly carotid mean energy and energy PI, better explain the vascular-cognitive nexus than conventional measures.