Vascular determinants of hippocampal viscoelastic properties in healthy adults across the lifespan

• Published in: Journal of cerebral blood flow and metabolism 2023-11, Vol.43 (11), p.1931-1941
• Main Authors: Sanjana, Faria, Delgorio, Peyton L, DeConne, Theodore M, Hiscox, Lucy V, Pohlig, Ryan T, Johnson, Curtis L, Martens, Christopher R
• Format: Article
• Language: English
• Subjects: Adult; Blood Flow Velocity - physiology; Carotid Arteries - diagnostic imaging; Cross-Sectional Studies; Hippocampus - diagnostic imaging; Humans; Longevity; Original; Vascular Stiffness - physiology
• ISSN: 0271-678X; 1559-7016; 1559-7016
• DOI: 10.1177/0271678X231186571

Arterial stiffness and cerebrovascular pulsatility are non-traditional risk factors of Alzheimer’s disease. However, there is a gap in understanding the earliest mechanisms that link these vascular determinants to brain aging. Changes to mechanical tissue properties of the hippocampus (HC), a brain structure essential for memory encoding, may reflect the impact of vascular dysfunction on brain aging. We tested the hypothesis that arterial stiffness and cerebrovascular pulsatility are related to HC tissue properties in healthy adults across the lifespan. Twenty-five adults underwent measurements of brachial blood pressure (BP), large elastic artery stiffness, middle cerebral artery pulsatility index (MCAv PI), and magnetic resonance elastography (MRE), a sensitive measure of HC viscoelasticity. Individuals with higher carotid pulse pressure (PP) exhibited lower HC stiffness (β = −0.39, r = −0.41, p = 0.05), independent of age and sex. Collectively, carotid PP and MCAv PI significantly explained a large portion of the total variance in HC stiffness (adjusted R2 = 0.41, p = 0.005) in the absence of associations with HC volumes. These cross-sectional findings suggest that the earliest reductions in HC tissue properties are associated with alterations in vascular function.