Background and purpose: During normal aging, the cerebral autoregulation mechanism and the CO2-induced cerebral reserve capacity remain unaffected. This led to the suggestion of a wide compensatory range of mechanisms responsible for the cerebral blood flow regulation. The authors investigated the neurovascular coupling mechanism for age-related changes. Because several authors criticized the comparison between higher and younger age groups, the current authors restricted their study on volunteers between 10 and 60 years.
Methods: Twenty healthy volunteers in the age group of 10 to 20, 20 to 40, and 40 to 60 each without cerebrovascular risk factors were enrolled in this study; they were aged 16.3 +/- 3.4 SD years (9 boys), 32.7 +/- 2.3 SD years (9 men), and 53.1 +/- 5.3 SD years (10 men). A functional transcranial Doppler test was performed using a visual stimulation paradigm. The resultant flow velocity changes in the posterior cerebral artery were analyzed using a control system approach. Resting flow velocity and each of the control system parameters, which were time delay, attenuation, natural frequency, rate time, and gain, were compared between groups statistically.
Results: Control system parameters remained statistically unchanged between groups, whereas the resting flow velocity decreased significantly by age.
Conclusions: The neurovascular coupling mechanism seems to be unaffected by moderate aging as estimated by Doppler parameters. Vasoregulative dysfunction in patients at vascular risk is more likely to be caused by the risk factor rather than by age.