Arterial and venous flow dynamics are modified by age in the non-human primate.

Growing evidence suggests that vascular abnormalities contribute to neurodegenerative processes during ageing. With the anticipated rise in the elderly population, we aimed to characterise arterial and venous flow dynamics, which reflect cardio-cerebro-vascular conditions, using a preclinical model: the marmoset monkey. We employed MRI protocols to image brain and intracranial vessel anatomy. We adapted the phase-contrast MRI protocol to measure blood dynamics synchronised with the ECG signal in the carotid arteries, basilar trunk, superior sagittal, and straight sinuses. We imaged both young and old healthy marmosets. Our analysis revealed a similar chronological sequence of maximal blood flow values in the various arteries and sinuses for both young and old marmosets; however, the peaks occurred earlier in the cardiac cycle for the older group. Furthermore, we observed shorter arterio-venous delays in older marmosets, suggesting ageing-related cardiovascular and cerebrovascular changes. We analysed the temporal progression of arterial and venous blood volumes within the cranial system at the cardiac cycle scale, providing valuable insights into the constraints on the craniospinal system. An illustration of the relationships between input flow and output flow revealed a characteristic hysteresis effect, indicating an age-dependent behaviour of the venous system.