The Effects of Dietary Caffeine Use and Abstention on Blood Oxygen Level-Dependent Activation and Cerebral Blood Flow.
BACKGROUND
Caffeine is a known vasoconstrictor that reduces resting cerebral blood flow (CBF) throughout the brain. This effect may be problematic in functional magnetic resonance imaging (fMRI) research, as the blood oxygen level-dependent (BOLD) signal is a complex interaction of CBF and other factors that are dependent on changes in neural activity. It is unknown whether changes in the BOLD signal during an fMRI experiment could be affected by subjects' recent use or abstinence from dietary caffeine.


METHODS
Here, we report two similar studies (n=45 and 17) that measure the effects of caffeine on BOLD activation, BOLD time course parameters, and CBF. Using a factorial design, low, moderate, and high caffeine consumers received either caffeine (250 mg) or placebo during normal caffeine use (satiated state) or after 30 hours of abstention (abstinent state). The fMRI of a reaction time task and resting-state CBF were collected.


RESULTS
In general, acute caffeine administration reduced the time to peak and full width at half maximum of the BOLD time course, and CBF across both studies. Caffeine also produced a small reduction in BOLD activation. The majority of these reductions across measures were moderated by neither the level of caffeine use, nor the abstinent or satiated state.


CONCLUSIONS
These results suggest that dietary caffeine use does not produce a significant effect on task-related BOLD activation.
Department of Psychiatry and Behavioral Sciences, Duke University Medical Center , Durham, North Carolina.
Merideth A
MA
Addicott
Department of Radiation Oncology, Wake Forest University School of Medicine , Winston-Salem, North Carolina.
Ann M
AM
Peiffer
Department of Radiology, Wake Forest University School of Medicine , Winston-Salem, North Carolina.
Paul J
PJ
Laurienti