| Effect | Decrease |
| Trial Design | Double blind |
| Trial Length | 24 hours |
| Number of Subjects | 102 |
| Sex | Both Genders |
| Age Range | 18-29, 30-44, 45-64 |
| Body Types | Overweight, Average |
102 light, nondependent caffeine users were subject to varying doses of caffeine and tested for its psychostimulatory responses.
Sedation was significantly lowered and stimulation was higher, although still lesser to 20mg d-amphetamine (used as comparison) even when at 450mg caffeine. No significant interactions on euphoria or desire of 'more drug' were noted with caffeine, but were with d-amphetamine.
Performance on working memory was decreased at the 450mg dosage but processing speed at all doses was increased, most significantly at the 450mg dosage.
