Panic Provocation Studies with Placebo

In panic disorder (PD) and agoraphobia with panic attacks, periodic panic attacks occur, characterized by the sudden onset of such physical symptoms as paresthesia, dizziness, palpitations, etc and are accompanied by a sensation of extreme fear (1). Panic attacks may be provoked by using some probes. Procedures that provoke symptoms of a specific illness have obvious value as tools for the study of that illness and may have important clinical uses as well (2). Pharmacological challenges in anxiety disorders generally and in PD specifically may serve as a diagnostic test, as a predictor of treatment response, as a means of assessing treatment adequacy, and as a predictor of relapse (3). The use of pharmacological challenges in PD is unique in that the clinical phenomenon of central interest (i.e., the panic attack) can be readily provoked and assessed in the clinical laboratory setting (4). Carbon dioxide (CO2) both 5% and 35% have been reported to be anxiogenic in patients with PD (5,6,7). It has been shown that compounds which are effective in PD decrease CO2 sensitivity and ineffective ones cannot (8). Another effective probe, cholecystokinin (CCK) is an octapeptide found regionally in the gastrointestinal tract and brain, where it acts as a neurotransmitter and neuromodulator. In some neurons, it is colocalized with other neurotransmitters, particularly dopamine (DA) and gamma-aminobutyric acid (GABA), and GABA seems to be involved in the regulation of CCK release. Interest in CCK`s role in anxiogenesis arose from evidence that it stimulates rat cortical and hippocampal neurons, effects that are blocked by benzodiazepine agonists (9). Panic Provocation Studies with Placebo