New developments in the neurobiological basis of anxiety disorders.

Generalized anxiety disorder (GAD) is a chronic disorder that often precedes the development of, and is comorbid with, depression. Investigation of the neurobiological basis of GAD has provided suggestive evidence to implicate dysfunction of serotonergic and noradrenergic systems in the expression of GAD, as well as the depressive disorders. Hence, there may be a neurobiological link between GAD and depression through the activity of the serotonin and norepinephrine systems. The use of various anxiolytics and antidepressants, including benzodiazepines, tricyclic antidepressants, selective serotonin reuptake inhibitors, and serotonin and norepinephrine reuptake inhibitors in the treatment of GAD is reviewed. The neurobiological relationship between GAD and depression, and the frequent comorbidity of these disorders, suggests that agents with a dual action on the serotonin and norepinephrine systems may potentially offer superior benefits in the management of patients with anxiety and depressive disorders.