Neurobiological mechanisms of panic anxiety: biochemical and behavioral correlates of yohimbine-induced panic attacks.

The effects of yohimbine, an alpha 2-adrenergic receptor antagonist, on anxiety, blood pressure, heart rate, and plasma levels of the norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) and cortisol were determined in 20 healthy subjects and 68 patients who had agoraphobia with panic attacks or panic disorder. Yohimbine produced panic attacks meeting DSM-III criteria in 37 patients and one healthy subject. The patients reporting yohimbine-induced panic attacks had significantly larger increases in plasma MHPG, cortisol, systolic blood pressure, and heart rate than the healthy subjects. These findings support the hypothesis relating high noradrenergic neuronal activity to the pathophysiology of panic attacks in a subgroup of panic disorder patients.