General anxiety disorder is associated with irregular levels of neurotransmitters in the brain. Neurotransmitters are chemicals that carry signals across nerve endings. Neurotransmitters that seem to involve anxiety include norepinephrine, GABA (gamma-aminobutyric acid), and serotonin.
Norepinephrine is concentrated in the locus ceruleus (nerve cluster that lies near the brain's fourth ventricle). Increased activity in the locus ceruleus is associated with anxiety, and decreased activity in the locus ceruleus diminishes anxiety. Increased levels of GABA and serotonin seem to reduce anxiety. All of these neurotransmitters interact during heightened anxiety.
The psychodynamic theory of psychology sees anxiety as an alerting mechanism that arises when our unconscious motivations clash with the constraints of our conscious mind. This conflict is intensified in people with GAD.
Behavioral theory holds that anxiety results from not knowing how to behave in a given situation. The possibility of suffering negative consequences because of inappropriate behavior may result in hesitation and inaction. The anxiety may be generalized to similar situations. For example, anxiety over taking a particular test may be generalized to taking all tests in the future.