title: The effect of black tea and caffeine on regional cerebral blood flow measured with arterial spin labeling.
abstract: Black tea consumption has been shown to improve peripheral vascular function. Its effect on brain vasculature is unknown, though tea contains small amounts of caffeine, a psychoactive substance known to influence cerebral blood flow (CBF). We investigated the effects on CBF due to the intake of tea components in 20 healthy men in a double-blinded, randomized, placebo-controlled study. On separate days, subjects received a single dose of 184 mg caffeine (equivalent to one strong espresso coffee), 2,820 mg black tea solids containing 184 mg caffeine (equivalent to 6 cups of tea), 2,820 mg decaffeinated black tea solids, or placebo. The CBF and cerebrovascular reactivity (CVR) to hypercapnia were measured with arterial spin labeled magnetic resonance imaging (MRI) before and 2 hours after administration. We found a significant global reduction with caffeine (20%) and tea (21%) in gray matter CBF, with no effect of decaffeinated tea, suggesting that only caffeine influences CBF acutely. Voxelwise analysis revealed the effect of caffeine to be regionally specific. None of the interventions had an effect on CVR. Additional research is required to conclude on the physiologic relevance of these findings and the chronic effects of caffeine and tea intake on CBF.
authors.affiliation: Centre for Imaging Sciences, Institute of Population Health, University of Manchester, Manchester, UK. rishma.vidyasagar@manchester.ac.uk
authors.forename: Rishma
authors.initials: R
authors.lastname: Vidyasagar
authors.forename: Arno
authors.initials: A
authors.lastname: Greyling
authors.forename: Richard
authors.initials: R
authors.lastname: Draijer
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Corfield
authors.forename: Laura M
authors.initials: LM
authors.lastname: Parkes
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply* / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D028241:Camellia sinensis / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004311:Double-Blind Method; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012039:Regional Blood Flow / Q000187:drug effects*; D013113:Spin Labels; D013662:Tea / Q000378:metabolism*; D055815:Young Adult
chemical_list: D013113:Spin Labels; D013662:Tea; D002110:Caffeine