| Summary: | Hypertension, even when pharmaceutically controlled, may accelerate arterial stiffening and impair changes in blood flow necessary to support neural activity (neurovascular coupling [NVC]). Optimal NVC requires continuous, non-pulsatile flow, which is partially determined by extra- and intra-cranial vessel function.
Purpose: Examine extra- and intra-cranial hemodynamics during cognitive activity in adults with well-controlled hypertension and without hypertension.
Methods: 30 middle-aged, medicated hypertensive and 30 age-, sex-, and Body Mass Index (BMI)-matched non-hypertensive adults (56 ± 6 yrs, BMI 28.2 ± 2.9 kg/m2; 32 men) underwent cerebrovascular measures at rest and during a Stroop task. Applanation tonometry and ultrasound were used to assess aortic and carotid (single-point) Pulse Wave Velocity (PWV), respectively. Ultrasound and Doppler were used to measure carotid and Middle Cerebral Artery (MCA) blood velocity pulsatility. Near-infrared spectroscopy was used to measure prefrontal oxygenation (tissue saturation index; TSI). Accuracy and reaction times were computed to assess cognitive performance.
Results: Stroop performance was similar between groups (p > 0.01). Aortic and carotid PWV increased, carotid pulsatility decreased (p0.01; Table 1). Reductions in CCA pulsatility during the Stroop were associated with increases in cortical TSI in the combined sample (r = 0.27), suggesting extracranial hemodynamics may play a role in optimizing intracranial NVC.
Conclusions: Our findings indicate that middle-age adults with medically-controlled hypertension display similar intra- and extra-cranial cerebrovascular reactivity to adults without hypertension. Additionally, adults with and without hypertension may utilize reductions in extracranial pulsatility during NVC to minimize intracranial pulsatility and improve downstream cerebral oxygenation.
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