Dynamic cerebral autoregulation is unaffected by aging.
OBJECTIVE
Normal aging is associated with marked changes in the cardiovascular and cerebrovascular systems. Although cerebral autoregulation (CA) is impaired in certain disease states, the effect of age per se on dynamic CA in humans is unknown and the focus of this study.


METHODS
Twenty-seven young subjects (</=40 years) and 27 older subjects (>/=55 years), matched for sex and systolic blood pressure (BP), underwent measurement of cerebral blood flow velocity by transcranial Doppler ultrasound and noninvasive beat-to-beat arterial BP measurement during induced and spontaneous dynamic BP stimuli. A standard dynamic autoregulatory index (ARI) was derived for each spontaneous and induced dynamic BP stimulus to include the step response, as well as cardiac baroreceptor sensitivity (BRS), for the 2 groups.


RESULTS
The mean age of the young group was 29+/-5 years, and that of the older group was 68+/-5 years. Cardiac BRS was reduced in the older group (8. 6+/-4.5 versus 16.9+/-8.8 ms/mm Hg; P:<0.0001). However, no age-related differences were demonstrated in step response plots or in ARI values for any pressor or depressor dynamic BP stimulus (P:=0. 62), with mean ARI values for all stimuli combined being 4.9+/-1.8 for the young group and 5.0+/-2.3 for the older group.


CONCLUSIONS
Although increasing age is associated with a decrease in cardiac BRS, dynamic CA, as assessed by step response analysis as well as cerebral blood flow responses to transient and induced BP stimuli, is unaffected by aging.
Carey
B J
BJ
Division of Medicine for the Elderly, University of Leicester, Glenfield Hospital, Leicester. brian.carey@glenfield-tr.trent.nhs.uk
Eames
P J
PJ
Blake
M J
MJ
Panerai
R B
RB
Potter
J F
JF
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006321:Heart / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011311:Pressoreceptors / Q000502:physiology; D017585:Ultrasonography, Doppler, Transcranial / Q000706:statistics & numerical data