Caffeine and human cerebral blood flow: a positron emission tomography study

Life Sci. 1990;47(13):1141-6. doi: 10.1016/0024-3205(90)90174-p.


Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased paCO2 and increased systolic blood pressure significantly; the change in paCO2 did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Administration, Oral
  • Adult
  • Anxiety Disorders / blood
  • Blood Flow Velocity / drug effects
  • Blood Pressure / drug effects
  • Brain / blood supply
  • Brain / drug effects*
  • Caffeine / administration & dosage
  • Caffeine / blood
  • Caffeine / pharmacology*
  • Carbon Dioxide / blood
  • Cerebrovascular Circulation / drug effects*
  • Epinephrine / blood
  • Female
  • Humans
  • Injections, Intravenous
  • Male
  • Norepinephrine / blood
  • Partial Pressure
  • Tomography, Emission-Computed


  • Carbon Dioxide
  • Caffeine
  • Norepinephrine
  • Epinephrine