is often observed in panic disorder patients.. Anxiogenic properties of CCK were demonstrated in various animal models of anxiety, and results of only one of these studies suggested anxiolytic rather than anxiogenic properties of CCK.7 Anxiogenic qualities of CCK The first human study which demonstrated CCK anxiogenic properties was conducted by De Montigny in 1989. The study did not include a control group and all participants were healthy volunteers. Upon injection of various doles of CCK (20-100 g) 70% of participants developed panic attack symptoms.7 This discovery was confirmed a year later by Bradwejn and colleagues, who have contributed heavily to the research on the role of CCK as panicogenic agent. In 1991 they confirmed De Montignys observation with the use of a double-blind experimental design.7 Unlike de Montigny, Bradwejns study included no healthy volunteers, but rather panic disorder patients, who were randomly subjected to injections of either 50 g of CCK or placebo. The procedure was repeated two times and results left no room for ambiguity: all participants panicked with CCK and none with placebo. It is important to notice, that CCK induced panic attacks did not differ, in patients opinions, from naturally occurring panic attacks and fit the criteria established by the DSM III-R. The next step in CCK research was to compare the responses of normal volunteers and panic disorder sufferers. In a double-blind controlled procedure designed by Bradwejn and colleagues PD sufferers and healthy volunteers received either 25 or 50 g of CCK-4 via injection.3 The procedure was repeated with placebo for each subject in the experimental and control groups. The subjects had to describe their symptoms after each injection to the investigators, who recorded the onset and duration of symptoms. After the disappearance of symptoms the participants were assessed with the panic inventory consistent with DSM-III-R diagnostic cr...
