Blood-brain barrier permeability in response to caffeine challenge

Purpose Caffeine is known to alter brain perfusion by acting as an adenosine antagonist, but its effect on blood-brain barrier (BBB) permeability is not fully elucidated. This study aimed to dynamically monitor BBB permeability to water after a single dose of caffeine tablet using a non-contrast MRI technique. Methods Ten young healthy volunteers who were not regular coffee drinkers were studied. The experiment began with a pre-caffeine measurement, followed by four measurements at the post-caffeine stage. Water-extraction-with-phase-contrast-arterial-spin-tagging (WEPCAST) MRI was used to assess the time dependence of BBB permeability to water following the ingestion of 200 mg caffeine. Other cerebral physiological parameters including cerebral blood flow (CBF), venous oxygenation (Y-v), and cerebral metabolic rate of oxygen (CMRO2) were also examined. The relationships between cerebral physiological parameters and time were studied with mixed-effect models. Results It was found that, after caffeine ingestion, CBF and Y-v showed a time-dependent decrease (p < 0.001), while CMRO2 did not change significantly. The fraction of arterial water crossing the BBB (E) showed a significant increase (p < 0.001). In contrast, the permeability-surface-area product (PS), i.e., BBB permeability to water, remained constant (p = 0.94). Additionally, it was observed that changes in physiological parameters were non-linear with regard to time and occurred at as early as 9 min after caffeine tablet ingestion. Conclusion These results suggest an unchanged BBB permeability despite alterations in perfusion during a vasoconstrictive caffeine challenge.

Automated summary

This study used non-contrast MRI technique to dynamically monitor the effect of caffeine on blood-brain barrier (BBB) permeability to water. The results showed that caffeine ingestion led to decreased cerebral blood flow and venous oxygenation, but did not affect BBB permeability to water. These findings provide important insights into the effects of caffeine on the nervous system.