ACUTE DOSE-EFFECT RELATIONSHIPS OF CAFFEINE AND MENTAL PERFORMANCE, EEG, CARDIOVASCULAR AND SUBJECTIVE PARAMETERS

The present study investigated the dose-effect relationship of caffein e on mental performance using a caffeine-sensitive rapid information p rocessing task (RTP) in a pre/post cross-over design. Twenty female no nsmoking regular coffee drinkers received 0, 1.5, 3 and 6 mg/kg caffei ne in a balanced order and the measurements were extended to cardiovas cular, EEG and mood parameters. Surprisingly, the dose-effect curves f or the different parameters were rather heterogeneous. Whereas increas ing effects with increasing caffeine doses were observed for alpha- an d beta-EEG frequencies, anxiety, wakefulness, and some coffee ratings, negative dose-effect relationships were obtained for RIP processing r ate and blood pressure. No apparent dose-effect relationships were see n for reaction time and motor activity. Thus, it was concluded that th e dose-response relationships are rather shallow and heterogeneous and that the different parameters have different ranges in which they are sensitive to caffeine. The caffeine doses which might have beneficial behavioral effects are at the lower end of the tested dose range and comparable to those found in caffeine-containing beverages.