Anxiety Disorder : DEFINITION
Anxiety can be described as an uncomfortable feeling of vague fear or apprehension accompanied by characteristic physical sensations. It is a normal and often beneficial response to situations that humans perceive as threatening, frightful, or otherwise disturbing.
PATHOPHYSIOLOGY
A neurocircuit arising from the output pathways of the central nucleus of the amygdala is thought to mediate fear and anxiety responses in humans.Dysregulated or exaggerated output through various amygdala-related circuits may be a common element underlying the different anxiety disorders, but the specific type of dysfunction probably differs among the various disorders. Several neurotransmitter systems have been linked to the neurobiology of anxiety: the inhibitory amino acid, ?-aminobutyric acid (GABA); the monoamine neurotransmitters, serotonin and norepinephrine; the excitatory amino acid, glutamate; and the neuropeptides, cholecystokinin (CCK), corticotrophin-releasing factor (CRF), neuropeptide Y (NPY), and substance P.2,3 Much of the evidence for these biologic processes has come from research on drugs that are used either to treat anxiety or to induce anxiety. Discovery of the anxiolytic effects of benzodiazepines in the early 1960s marked the beginning of this era of research. However, the anxiety-reducing properties of alcohol and barbiturates were recognized long before that time.