How does the brain respond to fear in people with anxiety disorders?

The amygdala, a small structure deep in the brain, coordinates the body's fear response. Part of the limbic system, a complex group of structures associated with emotions, it helps mount a swift response to perceived and complex stimuli. The amygdala also plays a role in the early stages of extinguishing an embedded fear -- that is, learning not to be afraid in a situation that previously sparked fear.

In the face of danger, two brain circuits become active. One circuit feeds sensory information about the danger — the sight and smell of a fire, for example — to the cerebral cortex (the rippled outer layer of gray matter jacketing both brain hemispheres), the thinking part of the brain. The cerebral cortex evaluates this information and makes a rational judgment about it. For example, that judgment may determine that the fire is small, but tell you to get out of the house anyway and call the fire department.

The other circuit relays the sensory information to the amygdala, which sends impulses to the autonomic nervous system. This system triggers the "fight-or-flight" response even before the cerebral cortex has made sense of the information. Once activated, it increases heart rate, routes blood to muscles, releases stress hormones and glucose into the bloodstream, and spurs other responses to help you respond quickly to the danger.

The amygdala stores memories of frightening events and other emotional experiences. In people with anxiety disorders, the amygdala may be so sensitive that it overreacts in situations that aren't threatening. Research on animals suggests that different parts of the amygdala are activated for different anxiety disorders.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.