Biological basis of generalized anxiety disorder.

Despite the considerable revisions to diagnostic criteria, recent data indicate that generalized anxiety disorder (GAD) is one of the most common anxiety disorders. Growing evidence also indicates that GAD is a serious illness, which frequently causes moderate impairment and often requires prolonged treatment. Thus, investigation of the biological correlates of GAD may be helpful in the development of effective treatments for this disorder. Recent data suggest possible abnormalities in the regulatory mechanisms of several important biological components in GAD patients. Maladaptive responses to stressful stimuli have been observed in the locus-ceruleus-norepinephrine-sympathetic nervous system, the hypothalamic-pituitary-adrenocortical axis, and the cholecystotin system. Abnormalities in other important CNS modulators, such as 5-HT and gamma-aminobutyric acid, may also be involved in the biology of GAD. In the following article, the authors will review the existing information regarding these potential biological abnormalities in GAD.