Frontal brain hypoactivity as a biological substrate of anxiety in patients with panic disorders.

Frontal brain asymmetry is associated with differences in the basic dimensions of emotion. It seems to reflect the activation of specialized systems for avoidance-withdrawal behavior. Since patients with panic disorder are characterized by having both negative emotions and avoidance-withdrawal behavior, we expected them to show greater asymmetry in the frontal hemisphere change activation. Near-infrared reflection spectroscopy was recorded from the left and right frontal regions of 23 patients with panic disorder without depression and from 31 healthy control participants in the following conditions: confrontation at rest with neutral (mushroom), anxiety-relevant (spider and snake) or anxiety-irrelevant but emotionally relevant stimuli (erotic picture). Emotional states and traits were assessed by the State-Trait Anxiety Inventory. The left frontal oxyhemoglobin in patients was significantly lower than in control subjects when confronted with anxiety-relevant or anxiety-irrelevant but emotionally relevant stimuli. There was no frontal brain asymmetry when patients or control subjects observed any stimuli. These data suggest that patients with panic disorder are characterized by having a greater decrease in the activation of a left frontal avoidance-withdrawal system in situations with a negative valence. The findings are interpreted as biological evidence for a disturbed cortical processing in patients with panic disorder.