Electrophysiological evidence for an inverse benzodiazepine receptor agonist in panic disorder.

Inverse agonists of the GABA(A) receptor clearly decrease the amplitudes of the spontaneous EEG in the beta-frequency range. Therefore, we tested the hypothesis that panic patients exhibit a reduction of the EEG's spectral power in the beta-frequency band. Ten unmedicated patients with panic disorder and agoraphobia according to DSM-III-R criteria and 10 matched controls were investigated under baseline conditions, after hyperventilation and 30 min after hyperventilation. EEG recordings from the position Pz and Cz were performed under eyes closed conditions. At baseline conditions the patients suffering from panic disorder depicted a reduced beta-power reaching statistically significance for lead position Pz. Immediately after hyperventilation for both channels we observed a decreased beta-power. After hyperventilation we observed the same situation as under baseline conditions. Taken together, our results point to the view that in panic disorder an endogenous inverse agonist of the GABA(A)-benzodiazepine receptor could be hypothesized.