Rapid tryptophan depletion following cognitive behavioural therapy for panic disorder.
OBJECTIVE
The aim of this study was to examine the effect of rapid tryptophan depletion (RTD) combined with a panicogenic challenge in patients with panic disorder who had responded to treatment with cognitive behavioural therapy (CBT). We hypothesised that RTD (compared with the control drink) would result in an increase in anxiety symptoms when provoked by a panicogenic challenge with the benzodiazepine antagonist, flumazenil.


METHODS
Nine patients with panic disorder who had responded to CBT received a tryptophan-free amino acid drink on one occasion and a control drink on the other in a double-blind crossover design. In addition, they received flumazenil and placebo infusions on each day.


RESULTS
Our hypothesis regarding the effects of RTD was supported by findings of a significant interaction between RTD and flumazenil on measures from visual analogues scales (total) and the Spielberger State Anxiety inventory. A somewhat unexpected finding was that in this group of CBT responders, the panicogenic effect of flumazenil was not completely blocked by treatment. This meant that although four of the nine subjects (44%) reported a panicogenic effect of flumazenil on the RTD day, this was not significantly different from the rate of panic attacks in response to flumazenil on the control day.


CONCLUSIONS
We suggest that the partial return of symptoms in response to flumazenil reflects a vulnerability to RTD in this group of panic disorder patients who had responded to treatment with CBT.
Bell
Caroline
C
Department of Psychological Medicine, University of Otago, Christchurch, New Zealand. caroline.bell@otago.ac.nz
Hood
Sean
S
Potokar
John
J
Nash
Jon
J
Adrover
Mariona
M
Frampton
Chris
C
Hince
Dana
D
Rich
Ann
A
Argyropoulos
Spilios
S
Nutt
David
D
D000328:Adult; D001007:Anxiety / Q000209:etiology*; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005442:Flumazenil / Q000494:pharmacology; D018757:GABA Modulators / Q000494:pharmacology; D006801:Humans; D008297:Male; D016584:Panic Disorder / Q000503:physiopathology / Q000628:therapy*; D011569:Psychiatric Status Rating Scales; D014364:Tryptophan / Q000172:deficiency*; D055815:Young Adult
D018757:GABA Modulators; D005442:Flumazenil; D014364:Tryptophan