Variability in cerebral blood flow velocity at rest and during mental stress in healthy individuals: Associations with cardiovascular parameters and cognitive performance.

This study analyzed variability in cerebral blood flow velocity (CBFV) and possible underlying physiological mechanisms during rest and a mental arithmetic task. Blood flow velocities were bilaterally recorded by transcranial Doppler sonography in the anterior and middle cerebral arteries of 43 participants. Electrocardiography, continuous blood pressure (BP) and respiratory recordings were additionally obtained. Fast Fourier transformation revealed a spectral profile with two main components in CBFV, one in the very low frequency (VLF, 0.01-0.025 Hz), and the other in the low frequency band (LF, 0.075-0.11 Hz). During the task, CBFV variability decreased. While heart rate variability and respiration had only weak impacts, BP variability was closely associated with CBFV variability. LF CBFV variability correlated negatively with task performance. The findings indicate a connection between peripheral and cerebral hemodynamics, presumably mediated by the passive pressure-flow relationship and neural mechanisms. LF CBFV variability may constitute a suitable marker of mental effort load.