DIFFERENTIAL-EFFECTS OF DOPAMINERGIC DRUGS ON ANXIETY AND AROUSAL IN HEALTHY-VOLUNTEERS WITH HIGH AND LOW ANXIETY

1. The appearance of frontal midline theta activity (Fm theta), the di stinct EEG theta rhythm in the frontal midline area during performance of a mental task, indicates relief from anxiety in humans. 2. The aut hors examined the effects of bromocriptine and sulpiride on anxiety an d arousal in 24 male university students with (Fm theta group, n=12) a nd without (non-Fm theta group, n=12) Fm theta. Subjects were given pl acebo, 2.5 mg bromocriptine and 100 mg sulpiride in a double-blind cro ssover design. 3. Blood samples were obtained, STAI scores were determ ined, and EEGs were recorded before and during the performance of an a rithmetic addition task. The test was repeated twice: before and 1 hr after drug administration. 4. Bromocriptine reduced the MIA concentrat ion in both groups; sulpiride caused an increase in both groups. In th e Fm theta group, bromocriptine did not alter the appearance time of F m theta, the state anxiety score or the task performance; sulpiride in creased the Fm theta amount and reduced the state anxiety but did not affect the task performance. In the non-Fm theta group, bromocriptine increased the Fm theta duration and reduced the state anxiety score bu t did not influence the task performance, while sulpiride reduced Fm t heta and increased the state anxiety but had no effect on the task per formance. 5. These results suggest that the sensitivity of presynaptic D2 receptors is higher in high-anxiety subjects compared with low-anx iety subjects, and that anxiolytic effects in high-anxiety humans and those in low-anxiety humans may be caused by decreased and increased D A activity, respectively. In addition, the stimulation of DA function may cause anxiogenic effects in high-anxiety individuals.