Characteristics of the anxiolytic effects of buspirone in high- and low-anxious normal humans assessed by frontal midline theta activity.

Fmtheta is a distinct theta activity in the frontal midline area that appears during performance of mental tasks. It is suggested that relief from anxiety might be reflected in the appearance of Fmtheta. In the present study, the anxiolytic effects of buspirone were investigated using 24 male university students with (Fmtheta group, n = 12) and without (non-Fmtheta group, n = 12) Fmtheta. The subjects were given placebo, buspirone 5 mg and 15 mg in a double-blind, crossover design. Blood samples were obtained, scores were made on the State Trait Anxiety Inventory (STAI), and EEGs were recorded before and during performance of an arithmetic addition. The test was repeated twice: before and 1 h after drug administration. In the Fmtheta group, buspirone dose-dependently produced a decrease in plasma 5-HT and 5-HIAA concentrations and in state anxiety scores and an increase in Fmtheta amounts. In the non-Fmtheta group, however, there were no differences in these items except for 5-HT concentration before and after buspirone administration. These results suggest that anxiety in the Fmtheta group is mainly correlated with 5-HT1A receptor function, and that buspirone may have anxiolytic effects in patients with reactive anxiety but not those with endogenous anxiety.