What role do genetics play in generalized anxiety disorder?

As with other anxiety disorders, certain abnormalities in the brain seem to predispose a person to generalized anxiety disorder (GAD). One is a low level of gamma-aminobutyric acid (GABA), a neurotransmitter that blocks the release of other neurotransmitters, thus modulating nerve impulses. Another is a low level of serotonin, a neurotransmitter that affects mood and sleep. Just how these chemical messengers influence anxiety is unknown, but anti-anxiety drugs and antidepressants that increase their levels relieve symptoms of generalized anxiety disorder.

Brain imaging studies of people with generalized anxiety disorder reveal other abnormalities: increased activity in the cortex and decreased activity in the basal ganglia. Although the precise implications are not clear, in general, such abnormalities indicate a problem with brain function that may prime the pump for an overreaction to stress. Because generalized anxiety disorder tends to run in families, experts believe that genes are at least partly responsible. Symptoms also surface or worsen under stress.