Caffeine reduces cerebrovascular reactivity in addition to lowering basal perfusion

Motivation: Caffeine, one of the widely used psychoactive substances is known to reduce basal cerebral blood flow (CBF). However, its effect on vasodilatory capacity has not been characterizedGoal(s): To evaluate the impact of Caffein on cerebrovascular reactivity (CVR)Approach: 8 healthy caffeine-naïve volunteers were scanned for baseline (pre-caffeine) and post-Caffeine CVR measurements using BOLD MRI and phase-contrast MRI (PC)-MRI during normal air breathing and hypercapnia using 5% CO2 enriched gas mixtureResults: There was a significant reduction in blood-flux (BF) during room-air (p=0.002) and hypercapnia (p=0.0015) post caffeine administration (variation=33.7% and 41.3% respectively). PC-CVR and BOLD-CVR were reduced by 32.7%(p=0.006) and 22.5%(p=0.006) respectivelyImpact: This study's findings provide valuable insights into the impact of caffeine on cerebrovascular reactivity (CVR), revealing a significant reduction after caffeine intake. Findings would be beneficial in reducing the inter-subject variability of CVR by improving the sensitivity in detecting abnormalities.