ABNORMAL BRAIN HEMODYNAMIC-RESPONSES DURING PASSIVE ORTHOSTATIC CHALLENGE IN PANIC DISORDER

Objective: Autonomic dysregulation and cerebral blood flow (CBF) abnor malities have been reported in patients with anxiety disorders and, mo re recently, in panic disorder. Variations in the middle cerebral arte ry velocity (measured by transcranial Doppler technique), heart rate, and blood pressure during a tilting-table test were used as nonanxioge nic procedures to explore these abnormalities. Method: Mean flow veloc ity in the right middle cerebral artery, heart rate, and blood pressur e were monitored at rest and during a 70 degrees tilting-table test. T hree groups of patients were studied: 11 patients (eight women and thr ee men; mean age=31.1 years, SD=8.0) with a diagnosis of panic disorde r within 6 months of the onset of the disorder, nine asymptomatic pati ents (two men and seven women; mean age=35.0, SD=6.3) with a previous diagnosis of panic disorder who were in full remission of symptoms and had been drug free for at least 6 months, and 10 normal comparison su bjects (two men and eight women; mean age=31.1, SD=5.2). Results: Both patients with acute panic disorder and patients with remitted panic d isorder showed a significant percent reduction of right middle cerebra l artery mean flow velocity compared with normal subjects following ti lting to the upright position. No significant differences were observe d for blood pressure and heart rate. Conclusions: Patients with panic disorder, both during the acute phase of the illness and after clinica l recovery, show an exaggerated drop in CBF during tilting. Since thes e findings are similar, although attenuated in intensity, to those whi ch are observed in dysautonomic illnesses, one possible interpretation is that of panic disorder as a subclinical form of autonomic dysreact ivity.