title: The effect of age on cerebrovascular reactivity to cold pressor test and head-up tilt.
abstract: OBJECTIVE
  To compare the cold pressor test (CPT) and head-up tilt (HUT) responses of the older and younger healthy individuals by transcranial Doppler.
  
  
  METHODS
  Forty healthy volunteers were divided into two age groups (18-39 years, 40-69 years). Mean blood velocity (v(m)) in both middle cerebral arteries was monitored during CPT and HUT. Mean arterial blood pressure, heart rate and end-tidal CO(2) (Et-CO(2)) were measured simultaneously.
  
  
  RESULTS
  The v(m) increased by 7.1% during CPT and decreased by 10.1% during HUT. The v(m) responses were significantly lower in the older group (P < 0.01). Linear regression analysis showed a significant effect of age on dv(m) during both CPT (P < 0.01) as well as HUT (P < 0.01).
  
  
  CONCLUSIONS
  The age affected the v(m) responses to CPT and HUT in the group of older subjects.
authors.affiliation: Department of Neurology, Laboratory of Neurosonology, University Medical Center Ljubljana, Slovenia. janja.pretnar@siol.net
authors.forename: J P
authors.initials: JP
authors.lastname: Oblak
authors.forename: M
authors.initials: M
authors.lastname: Zaletel
authors.forename: B
authors.initials: B
authors.lastname: Zvan
authors.forename: T
authors.initials: T
authors.lastname: Kiauta
authors.forename: T
authors.initials: T
authors.lastname: Pogacnik
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000502:physiology; D010812:Physical Stimulation; D011187:Posture / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D012016:Reference Values; D018667:Tilt-Table Test