Cerebrospinal fluid production and dynamics in normal aging: a MRI phase-mapping study.

Magnetic resonance imaging (MRI) phase mapping was used for non-invasive evaluation of the to-and-fro motion of cerebrospinal fluid (CSF) in the cerebral aqueduct, and to measure the supratentorial CSF production in vivo, in 13 healthy volunteers to determine whether normal aging affects these parameters. Eight young healthy volunteers (mean age 29.8 years) and five elderly healthy volunteers (mean age 69.0 years) were examined, all were normal on conventional MRI. Slightly higher aqueductal CSF peak flow velocities and peak volume flow in both the caudal and rostral directions were found in the group of elderly healthy volunteers, however, this was not statistically significant. The calculated mean supratentorial CSF production rates in the two groups were almost identical, corresponding to approximately 900-1000 ml per 24 h, we suggest that supratentorial CSF production in healthy humans in fact occurs at this relatively high rate. Our study further suggests that the differences found in human CSF production rates are caused by interindividual factors other than age.