Effects of dietary caffeine on topographic EEG after controlling for withdrawal and withdrawal reversal.
OBJECTIVE
Despite several decades of research into the effects of caffeine on EEG, few consistent findings have emerged. Notwithstanding the likelihood that differences in methodology may explain some of the inconsistency, confidence in the published findings is undermined by the failure in previous studies to control for the effects of caffeine withdrawal and withdrawal reversal.


METHODS
Participants (n = 22) alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) 3 times daily for 4 consecutive weeks. EEG activity was measured at 32 sites during eyes closed, eyes open, and performance of a vigilance task.


RESULTS
Caffeine was found to have few and modest effects on EEG in the theta and alpha bandwidths, and no effects in the delta and beta bandwidths. Evidence was found of withdrawal, withdrawal reversal, and tolerance in relation to observed increases in theta power during task performance; withdrawal and withdrawal reversal in relation to increases in alpha power during all three behavioural conditions (eyes closed, eyes open, and task performance), and withdrawal-induced adverse effects in relation to aspects of subjective mood.


CONCLUSIONS
The finding of similar increases in theta power following caffeine challenge and acute caffeine withdrawal casts doubt on whether caffeine may be viewed as having direct stimulant effects. Results could suggest that change in drug state, whether in the form of acute caffeine withdrawal or challenge, may be disruptive to electrophysiological activity in the brain.
Keane
Michael A
MA
National University of Ireland, Galway, Ireland.
James
Jack E
JE
Hogan
Michael J
MJ
D000293:Adolescent; D000328:Adult; D000339:Affect / Q000187:drug effects; D000704:Analysis of Variance; D001288:Attention / Q000187:drug effects*; D001931:Brain Mapping; D002110:Caffeine / Q000008:administration & dosage* / Q000009:adverse effects; D000697:Central Nervous System Stimulants / Q000008:administration & dosage* / Q000009:adverse effects; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000187:drug effects*; D012463:Saliva / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013997:Time Factors
D000697:Central Nervous System Stimulants; D002110:Caffeine