The effect of age on cerebrovascular reactivity to cold pressor test and head-up tilt

OBJECTIVE: To compare the cold pressor test (CPT) and head-up tilt (HUT) responses of the older and younger healthy individuals by transcranial Doppler. SUBJECTS AND 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). CONCLUSION: The age affected the v(m) responses to CPT and HUT in the group of older subjects.