Panic disorder is one of the most prevalent and disabling psychiatric disorders. Brain regions such as amygdala, hippocampus, periaqueductal gray (PAG), locus coeruleus, parahippocampal gyrus, frontal cortex, and thalamus has been reported to be related with the pathophysiology and treatment outcome in panic disorder. Paroxetine has been used as primary agent for treatment of panic disorder but there is little information on how paroxetine affects the brain function in patients with panic disorder.

The specific aim of this study is to examine the differences in brain activity between responders and nonresponders and to determine the predictor of paroxetine treatment in patients with panic disorder in terms of brain activity.

Inclusion Criteria:

• panic disorder 20-60 years

Exclusion Criteria:

• history of major psychosis (schizophrenia or bipolar disorder), social phobia, obsessive-compulsive disorder, and generalized anxiety disorder, and posttraumatic stress disorder, alcohol abuse and dependence, current regular use of benzodiazepines
• less than 17 on the HAM-D