Sex differences in cerebral pulsatility and damping: A 4D flow MRI study.

Cerebral pulsatility is a potential marker of cerebrovascular health, yet little is understood about sex differences in cerebral pulsatility with age, especially within different cerebral arteries. Additionally, cerebral damping can blunt cerebral pulsatility and might decline with age. Therefore, we aimed to identify sex differences in cerebral pulsatility and damping across the adult lifespan. Forty-three young, 67 middle-aged and 54 older adults had cerebral haemodynamics measured in the internal carotid arteries (ICAs), middle cerebral arteries (MCAs) and basilar artery using 4D flow MRI. Cerebral pulsatility index (PI) and damping factor (DF) were calculated. Young females had lower PI than young males in the ICAs (p < 0.05 for both), and middle-aged females had lower PI than middle-aged males in the right ICA (p < 0.01). In contrast, older females had greater PI than older males in the right ICA (p < 0.01) and in the right MCA (p < 0.05). Only the DF between the right ICA and MCA was lower in young females than in young males (p < 0.001). Taken together, females experience greater age-related elevations in cerebral pulsatility in comparison to males, especially within the proximal arteries of the anterior circulation. Damping was not different between males and females within the proximal arteries of anterior circulation, suggesting a different underlying mechanism. Overall, our findings suggest sex-specific trends in cerebral pulsatility with age, although the mechanisms driving this require further exploration.