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Biological Theories of Panic Disorder

What Does Research Show About the Biological Causes of Panic Disorder?

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Updated June 26, 2014

Serotonin, norepinephrine and dopamine are chemicals that act as neurotransmitters or messengers in the brain. They send messages between different areas of the brain and are thought to influence one’s mood and anxiety level. One theory of panic disorder is that symptoms are caused by an imbalance of one or more of these chemicals.

Support for this theory is the reduction of panic symptoms many patients experience when antidepressants, which alter brain chemicals, are introduced. Some examples are:

  1. Selective serotonin reuptake inhibitors SSRIs (such as Paxil, Prozac, amd Zoloft) work by increasing the level of serotonin in the brain.
  2. Serotonin-norepinephrine reuptake inhibitors (SNRIs) (such as Effexor and Cymbalta) work on both serotonin and norepinephrine.
  3. Tricyclic antidepressants (TCAs) (such as Anafranil and Elavil) affect serotonin, norepinephrine and to a lesser extent, dopamine.
  4. Monoamine oxidase inhibitors (MAOIs) (such as Nardil, Parnate) also inhibit panic by altering brain chemicals.

Gamma Aminobutyric Acid (GABA)

It is believed that gamma aminobutyric acid -- GABA -- is a chemical in the brain that modulates anxiety. GABA counteracts excitement in the brain by inducing relation and suppressing anxiety. Research has indicated that it may play a role in many mental health issues including anxiety and mood disorders.

Anti-anxiety medications such as Xanax, Ativan, or Klonopin, work because they target GABA receptors in the brain. These medications enhance the function of GABA resulting in a calm and relaxed state.

In several studies, GABA levels in individuals with panic disorder were lower than in control subjects with no history of panic. Future research to yield a better understanding of the role of GABA in mental health disturbances will, likely, lead to improved medication options for sufferers.

Metabolic Theories

Metabolic studies focus on how the human body processes particular substances. Many of these studies have shown that people with panic disorder are more sensitive to certain substances than are their non-panic counterparts.

For example, panic attacks can be triggered in people with panic disorder by giving them injections of lactic acid, a substance naturally produced by the body during muscular activity. Other studies have shown breathing air with elevated carbon dioxide can trigger panic attacks in those with the disorder. Caffeine, nicotine and alcohol have also been implicated as triggers for those with panic disorder.

What Does This All Mean?

Despite the implications of the research to date, no definitive laboratory findings can assist in the diagnose panic disorder. Chemical messengers in the brain and metabolic processes are complex and interactive. It may be that each of these theories has a specific importance in the development of panic disorder. Future research is needed to further delineate and tie together the biological causes of panic disorder.

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