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Updated: Mar 8, 2026
Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression
Published on: December 10, 2014
Evidence for hysteresis in the cerebral pressure-flow relationship in healthy men
Patrice Brassard1,2, Hélène Ferland-Dutil3,2, Jonathan D Smirl4
1Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada; patrice.brassard@kin.ulaval.ca.
The cerebrovasculature is more efficient at compensating for pharmacologically induced transient hypertension versus transient hypotension. Whether this phenomenon exists during nonpharmacologically induced hypertension and hypotension is currently unknown. We compared the percent change in mean velocity in the middle cerebral artery (MCAvmean) per percent change in mean arterial pressure (MAP) (%ΔMCAVmean/%ΔMAP) during transient hypertension and hypotension induced during squat-stand maneuvers performed at 0.05 Hz (20-s cycles) and 0.10 Hz (10-s cycles) in 58 male volunteers. %ΔMCAvmean/%ΔMAP was attenuated by 25% (P = 0.03, 0.05 Hz) and 47% (P < 0.0001, 0.10 Hz) during transient hypertension versus hypotension. Thus, these findings indicate that the brain in healthy men is better adapted to compensate for physiologically relevant transient hypertension than hypotension.NEW & NOTEWORTHY The novel finding of this study is that the change in middle cerebral artery mean flow velocity is attenuated during hypertension compared with hypotension physiologically induced by oscillations in blood pressure in men. These results support that the human brain is more effective at compensating for transient hypertension than hypotension.
The cerebrovasculature is more efficient at compensating for pharmacologically induced transient hypertension versus transient hypotension. Whether this phenomenon exists during nonpharmacologically induced hypertension and hypotension is currently unknown. We compared the percent change in mean velocity in the middle cerebral artery (MCAvmean) per percent change in mean arterial pressure (MAP) (%ΔMCAVmean/%ΔMAP) during transient hypertension and hypotension induced during squat-stand maneuvers performed at 0.05 Hz (20-s cycles) and 0.10 Hz (10-s cycles) in 58 male volunteers. %ΔMCAvmean/%ΔMAP was attenuated by 25% (P = 0.03, 0.05 Hz) and 47% (P < 0.0001, 0.10 Hz) during transient hypertension versus hypotension. Thus, these findings indicate that the brain in healthy men is better adapted to compensate for physiologically relevant transient hypertension than hypotension.NEW & NOTEWORTHY The novel finding of this study is that the change in middle cerebral artery mean flow velocity is attenuated during hypertension compared with hypotension physiologically induced by oscillations in blood pressure in men. These results support that the human brain is more effective at compensating for transient hypertension than hypotension.
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