Hypofrontality in panic disorder and major depressive disorder assessed by multi-channel near-infrared spectroscopy.

BACKGROUND: Panic disorder is a common and debilitating psychiatric disease; yet, the neurobiology of this disorder is not fully understood. Deficits in the prefrontal inhibitory control over hyperactivity of the anxiety-related neural circuit are implicated in the pathophysiological core of panic disorder. The aims of this study were to investigate whether panic disorder reveals frontal lobe dysfunction while performing the word fluency test by using multi-channel near-infrared spectroscopy and to compare the findings in panic disorder with those in major depressive disorder. METHODS: Twenty-one patients with panic disorder, 17 patients with major depressive disorder, and 24 healthy control subjects participated in the study. RESULTS: Both patients with panic disorder and with major depressive disorder showed similarly attenuated increases in oxy-hemoglobin during the word fluency test in the bilateral frontal regions, when compared to healthy control participants. Hypofrontality in panic disorder and major depressive disorder was most prominent in the left medial inferior frontal lobe. CONCLUSIONS: This study clarified that hypofrontality in panic disorder is evident even with neutral stimuli of little emotional load.