ABSTRACT
This chapter reviews the status of the neurobiological substrate of anxiety states. It discusses the neurobiological basis of panic and generalized anxiety disorders. Anxiety is a universal human experience, characterized by a fearful anticipation of an unpleasant event in the future. Postulated mechanisms of lactate-induced panic include central noradrenergic stimulation, increased central carbon dioxide sensitivity, and chemoreceptor hypersensitivity. Caffeine, a xanthine derivative, has been described as the most widely used psychotropic agent. Isoproterenol does seem to induce panic anxiety at least in a subgroup of panic disorder patients, and this may be due to mechanisms other than cardiac β-adrenergic sensitivity. Yohimbine, an alpha-2 adrenoceptor antagonist, can produce anxiety in psychiatric patients and normal volunteers. A genetic overlap with affective disorders has been suggested because of the beneficial effects of antidepressive drugs on panic disorder.
