Behavioral and cognitive effects of caffeine in boys and adult males.

The behavioral and cognitive effects of single doses of caffeine (3 and 10 mg/kg) were studied using a double blind placebo-controlled crossover design. Subjects were 19 prepubertal boys and 20 college age men. In general, children tended to show more objective effects of caffeine than did adults, with increased motor activity, increased speech rate, and decreased reaction time. Adults generally reported side effects following caffeine while children did not, and side effects were more prominent for adults with low habitual caffeine intake. Autonomic measures of arousal were similarly affected for both age groups. Caffeine had some effects that differed from those of amphetamine, indicating distinctive actions of the two stimulants.