REGIONAL CEREBRAL METABOLIC ASYMMETRIES REPLICATED IN AN INDEPENDENT GROUP OF PATIENTS WITH PANIC DISORDER

Background: Abnormal left/right (L/R) hemispheric ratios of regional c erebral glucose metabolic rates (rCMRglc) (hippocampus and inferior pr efrontal cortex) have been noted in unmedicated panic disorder patient s, Methods: An independent group of panic disorder patients placed on imipramine was studied with positron-emission tomography, testing for evidence of normalization versus persistence of the abnormal rCMRglc r atios, Differences in orbital frontal rCMRglc values between the imipr amine-treated and the previously reported unmedicated panic disorder p atients were tested examining for evidence that the differences would resemble those noted in obsessive-compulsive disorder (OCD) patients t reated with clomipramine. Results: We found the same abnormally low UR hippocampal and posterior inferior prefrontal rCMRglc ratios in the i mipramine-treated panic disorder patients, In addition, we found poste rior orbital frontal rCMRglc decreases in the imipramine-treated panic disorder patients compared with the unmedicated panic disorder patien ts, Conclusions: These abnormal asymmetries found in unmedicated panic disorder patients and now, in imipramine-treated panic disorder patie nts may reflect a trait abnormality, The orbital frontal rCMRglc diffe rences between the imipramine-treated and unmedicated patients are sim ilar to changes noted in OCD patients treated with clomipramine and ma y reflect direct or indirect effects of imipramine treatment in panic disorder patients, (C) 1998 Society of Biological Psychiatry.