The neurochemistry of anxiety: an update.

1. Recent neurochemical investigations have enhanced our understanding of the anxiety disorders. Emphasis has been placed on dysfunction in central benzodiazepine, serotonergic and noradrenergic systems. 2. Changes in activity of endogenous ligands for the benzodiazepine receptor or in benzodiazepine receptor sensitivity appear to modulate anxiety. 3. There is evidence of serotonergic involvement in anxiety, in that serotonin agonists may increase anxiety, whilst drugs that reduce serotonin function are anxiolytic. 4. Noradrenergic dysfunction, especially that of alpha-2-adrenoceptors, provides the strongest etiological evidence in the development of anxiety. 5. A number of testable hypotheses can be generated from our present knowledge. As a result, new and more specific treatments may become apparent for the anxiety disorders.