Effects of low doses of caffeine on cognitive performance, mood and thirst in low and higher caffeine consumers

  • Published: Psychopharmacology. October 2000, Volume 152, Issue 2, pp 167-173 (2000)
  • Authors: Smit, H.J. & Rogers, P.J
  • Date Added: 29 Dec 2013
  • Last Update: 29 Dec 2013
  • Format: pdf


This study measured the effects of 0, 12.5, 25, 50 and 100 mg caffeine on cognitive performance, mood and thirst in adults with low and moderate to high habitual caffeine intakes.


This was a double-blind, within-subjects study. Following overnight caffeine abstinence, participants (n=23) completed a test battery once before and three times after placebo or caffeine administration. The test battery consisted of two performance tests, a long duration simple reaction time task and a rapid visual information processing task, and a mood questionnaire (including also an item on thirst).

Key Findings:

  • Effects on performance and mood confirmed a psychostimulant action of caffeine.

  • All doses of caffeine significantly affected cognitive performance, and the dose-response relationships for these effects were rather flat.

  • The effects on performance were more marked in individuals with a higher level of habitual caffeine intake, whereas caffeine increased thirst only in low caffeine consumers.


Caffeine, cognitive performance, mood, thirst, rapid visual information, psychostimulant


This research demonstrates the effect of caffeine of cognitive performance and the mood of an individual who is used to different daily intakes.