Panic disorder among patients with chronic fatigue.

Among 200 adults with a chief complaint of chronic fatigue evaluated in an internal medicine practice, currently active panic disorder was diagnosed in 26 patients (13%), a frequency tenfold greater than that in the general population. Panic disorder preceded or was coincidental with the onset of chronic fatigue in 21 of these patients. In comparison with the rest of the study cohort, significantly more patients with panic disorder had a history of severe depression, including persistent thoughts of death or suicide. Moreover, more patients with panic disorder showed a lifetime tendency to have physical symptoms that remained unexplained after medical evaluation. Our findings suggest that treatable panic disorder is an important contributor not only to major depression and somatization, but also to the etiology and clinical presentation of chronic fatigue in patients in an outpatient practice.