Abstract
A deeper understanding of cerebral hemodynamics at rest is warranted to identify pathological changes associated with maladaptive changes in cognition. The need stems from evidence supporting cortical hypoperfusion during early adulthood as a predictor of late adulthood Alzheimer’s disease. PURPOSE: To disseminate which physiometrics can aid at identifying changes in cerebral blood flow. METHODS: A total of 22 young (22.55 ± 2.58 years) men participated in this study. Ultrasound sonography (doppler & pulse wave) was utilized to assess the peak systolic (PS) and end diastolic (ED) velocity (cm/s), while simultaneously measuring the vessel diameter (cm) in the internal (ICA) and external (ECA) carotid arteries. Blood flow volume (mL · min-1) for each artery was calculated [π(diameter/2)2 x velocity x 60] during PS and ED phases, and then used to calculate a hemodynamic ratio (ICA:ECA) between arteries. Fasted blood plasma was collected via antecubital venipuncture and utilized to quantify nitric oxide (NO), erythropoietin (EPO), phosphocreatine (PCr), and inorganic phosphate (Pi). The latter two were utilized to calculate a systemic surrogate (PCr:Pi) of metabolic status. Stepwise linear regression was utilized to identify the physiometrics affecting the ICA:ECA. An independent sample t-test was utilized to examine upper and lower 50th percentile comparisons within the ICA:ECA. All data was reported as mean ± standard deviation, with a statistical significance of p < 0.05 and Cohen’s d reported as effect size. RESULTS: The linear regression explained 36.6% of the variability in the ICA:ECA [F(2,18) = 6.769, p = 0.006]. For every 1 unit increase in diastolic blood pressure (p = 0.048), the ICA:ECA decreased by 0.024 units, indicating a greater blood flow volume towards the ECA. In addition, for every 1 unit increase in the PCr:Pi (p = 0.036), the ICA:ECA decreased by 0.623 units, also indicating a greater blood flow volume towards the ECA. Stratified into upper and lower than 50th percentile of the ICA:ECA, groups became highly dichotomous with no distribution near the median. This comparison revealed a significant difference [t(20) = 3.233, p = 0.004, d = 3.01] in the ICA PS (upper: 924.92 ± 190.55 mL· min-1; lower: 676.15 ± 169.80 mL· min-1) blood volume. The significant difference [t(20) = 2.293, p = 0.033, d = 1.22] was also present in the ICA ED (upper: 305.52 ± 76.12 mL· min-1; lower: 234.09 ± 69.88 mL· min-1) blood volume. CONCLUSION: In young men, having a lower diastolic blood pressure is linked to a greater intracranial blood flow. Such hemodynamic predominance might indicate a greater metabolic demand at rest, explaining why a higher ICA blood volume coexisted with a lower PCr:Pi. Conducting continuous follow-ups throughout late adulthood is critical to identify the extent to which maintaining a controlled blood pressure is beneficial in preventing cortical hypoperfusion and associated cognitive decline.
Recommended Citation
Hamlin, Kyle J.; Guadiana, Marcela; Guadiana, Camila; Koh, Yunsuk; and Moris, Jose M.
(2025)
"Intercranial Blood Flow is Determined by Diastolic Blood Pressure,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
17, Article 87.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss17/87
