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.

Endothelial Nitric Oxide Mediates Caffeine Antagonism of Alcohol-Induced Cerebral Artery Constriction

“…Our results are consistent with recent data documenting reduced human cerebral blood flow after acute administration of caffeine (Vidyasagar et al, 2013;see Discussion). Remarkably, when the two agents that caused vasoconstriction applied alone (50 mM ethanol; 10 mM caffeine) were mixed immediately before administration and coinjected into the carotid artery, cerebral arteriole diameter did not differ from preinfusion levels (Fig.…”

“…Remarkably, our in vivo and in vitro data from rat middle cerebral, resistance-size arteries are consistent with several in vivo studies in humans finding decreased cerebral blood flow after acute caffeine consumption (Mathew and Wilson, 1985;Cameron et al, 1990;Lunt et al, 2004;Addicott et al, 2009;Vidyasagar et al, 2013).…”

Acute caffeine administration impact on working memory-related brain activation and functional connectivity in the elderly: A BOLD and perfusion MRI study

“…As in younger cohorts, caffeine induced a global reduction of baseline perfusion in the range of 20% (Cameron et al, 1990;Mulderink et al, 2002;Vidyasagar et al, 2013). This effect is specific to caffeine, as for example the same effect was found for caffeine-containing tea, while decaffeinated tea did not reduce cerebral perfusion (Vidyasagar et al, 2013).…”

“…This effect is specific to caffeine, as for example the same effect was found for caffeine-containing tea, while decaffeinated tea did not reduce cerebral perfusion (Vidyasagar et al, 2013).…”

Arterial Spin Labeling Perfusion of the Brain: Emerging Clinical Applications

“…It may be less appreciated that even substances such as caffeine, which are widely distributed in beverages such as cola or coffee, significantly reduce the CBF estimated in ASL imaging, by about 20% in young adults (142) and even more in elderly controls (by approximately 23-25%) and mild cognitive impairment (MCI) (~30%) (143,144). Disease-related alterations in relative CBF, for example in dementia, are considerably smaller than caffeine-induced reduction of global CBF.…”