The application of positron emission tomography to the study of panic disorder.

Positron emission tomography was used to study eight patients with panic disorder who were vulnerable to lactate-induced panic, eight patients with panic disorder who were not vulnerable to lactate-induced panic, and 25 normal control subjects. Patients who were vulnerable to lactate-induced panic had several abnormalities in the resting, nonpanic state: an abnormal hemispheric asymmetry of parahippocampal blood flow, blood volume, and oxygen metabolism; abnormally high whole brain metabolism; and abnormal susceptibility to episodic hyperventilation. A hypothetical model for the neurobiology of panic disorder, involving the abnormal parahippocampal region and its afferent and efferent connections, is proposed.