A comparison of the effects of caffeine following abstinence and normal caffeine use

Abstract

Rationale: Caffeine typically produces positive effects on mood and performance. However, tolerance may develop following habitual use, and abrupt cessation can result in withdrawal symptoms, such as fatigue. This study investigated whether caffeine has a greater stimulant effect in a withdrawn state compared to a normal caffeinated state, among moderate daily caffeine consumers.

Materials and methods: Using a within-subjects design, 17 caffeine consumers (mean +/- sd = 375 +/- 101 mg/day) ingested placebo or caffeine (250 mg) following 30-h of caffeine abstention or normal dietary caffeine use on four separate days. Self-reported mood and performance on choice reaction time, selective attention, and memory tasks were measured.

Results: Caffeine had a greater effect on mood and choice reaction time in the abstained state than in the normal caffeinated state, but caffeine improved selective attention and memory in both states.

Conclusions: Although improvements in mood and reaction time may best explained as relief from withdrawal symptoms, other performance measures showed no evidence of withdrawal and were equally sensitive to an acute dose of caffeine in the normal caffeinated state.

Figures

Fig. 1

Average self-reported mood scores pre- and postcapsule administration. Mood scores were higher in the normal state than in the abstained state, and caffeine increased mood in the abstained state only. Mood decreased following placebo in the normal state (paired t test pre- to postcapsule: *p<0.01). Bars are SEM

Fig. 2

Average reaction times for the choice reaction time task after caffeine and placebo in the abstained and normal state. Caffeine decreased reaction times in the abstained state (paired t test placebo to caffeine: *p<0.01), but not in the normal state. Bars are SEM

Fig. 3

Average reaction times for the congruent and incongruent task conditions in the flanker selective attention task following placebo and caffeine in the abstained (AP and AC, respectively) and normal state (NP and NC, respectively). Caffeine decreased reaction time in the incongruent task (paired t test AP to AC and NP to NC: *p<0.05), but not in the congruent task. Bars are SEM

Fig. 4

Average accuracy (percent correct responses) for the 1-back and 2-back task conditions in the memory task following placebo and caffeine in the abstained (AP and AC, respectively) and normal state (NP and NC, respectively). Caffeine increased accuracy in the 1-back task (paired t test AP to AC: *p<0.05), but did not significantly affect accuracy in the 2-back task. Bars are SEM