Diurnal regulation of cerebrospinal fluid flow dynamics assessed using cardiac-corrected phase-contrast magnetic resonance imaging

Motivation: Circadian regulation of cerebrospinal fluid (CSF) flow dynamics during wakefulness is incompletely understood yet has relevance to the growing number of studies of neurofluid circulation dysfunction. Goal(s): To investigate repeated changes in CSF flow kinetics through the cerebral aqueduct over the time of day. Approach: In healthy adults, phase-contrast-MRI was repeated four times over the circadian cycle of wakefulness to obtain measures of CSF flux and velocity, which were contrasted with time of day. Results: Larger diastolic, retrograde flux and larger systolic, anterograde flux was observed from morning to afternoon, suggesting CSF flow becomes more hyperdynamic later in the day. Impact: This works provides new evidence in humans that CSF flow dynamics at the level of the cerebral aqueduct become more dynamic over the circadian rhythm of wakefulness, with a directionality similar to that observed with increasing age and neurodegeneration.