The American Psychiatric Association uses the label anxiety disorder to classify a number of psychiatric conditions characterized by extreme fearfulness, worry or dread. These illnesses include generalized anxiety disorder, panic attack, social anxiety, post traumatic stress disorder, obsessive compulsive disorder and various phobias. The Anxiety Disorders Association of America reports that anxiety disorders affect approximately 40 million adults in the United States, the most frequently diagnosed mental illness. Anxiety disorders are complex and have multiple factors, including biological factors that influence their development.
Genetic Factors
The complexity of an anxiety disorder makes its exact cause difficult to identify. Familial studies on identical and fraternal twins have been conducted to support genetic linkages of anxiety disorders. For example, if one identical twin has a diagnosed anxiety disorder, his identical twin is at greater risk of having an anxiety disorder than a non-identical sibling. The American Psychiatric Association reports that research findings have indicated that the panic attack anxiety disorder is most closely linked to a genetic predisposition.
Chemical Factors
In the U.S. Surgeon General's report on mental health, five key chemicals or neurotransmitters have been identified and linked to anxiety. Those neurotransmitters are serotonin; GABA, or gamma-aminobutyric acid; CRH, or corticotropin-releasing hormone; cholecystokinin; and norepinephrine. Although each of these chemicals has a specific function, they all work together to stabilize mood and associated behaviors. When there are slight imbalances in any of the chemicals, symptoms associated with anxiety disorders usually manifest. Many of the drugs prescribed to treat anxiety are designed to address either an over or under production in one or more of the neurotransmitters.
Neurological Factors
Two structures in the brain, the hippocampus and the amygdala, have been studied extensively. Research supports their linkage to anxiety disorders. The National Institute of Mental Health reports that these two structures are vital in the processing, interpreting and storage of sensory stimuli and their subsequent connection to emotions. Many people who suffer from post traumatic stress disorder have a significantly smaller hippocampus than those without the disorder. Although the cause of the diminished hippocampus is not known, its impact on anxiety disorders is well supported.
References
- American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders: DSM-IV-TR. Washington, DC: Author.
- Anxiety Disorders Association of America: Facts and Statistics
- University of Maryland Medical Center: Mental Health
- Mental Health: A Report of the Surgeon General
- National Institute of Mental Health: Anxiety Disorders
