Ventilatory effects of tryptophan depletion in panic disorder: a preliminary report.

On the basis of preclinical studies, we hypothesized that deficient serotonin neurotransmission may be associated with the respiratory hyperactivity and carbon dioxide sensitivity seen in panic disorder. We used the tryptophan depletion method to investigate the effects of transient reductions in serotonin on respiration in five patients with panic disorder and seven normal control subjects. During room air breathing, the patients showed significantly increased ventilation when tryptophan-depleted, while the normal subjects showed no significant changes in respiration. These preliminary data suggest that serotonergic manipulation may affect ventilatory indices, with panic disorder patients being particularly sensitive to the effect of tryptophan depletion.