The Etiology of Anxiety Disorders - Biological, Environmental and Life Events

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What is an Anxiety Disorder?

Most people experience anxiety at one time or another during their lifetime. An anxiety disorder, however, differs from typical anxiety in intensity, duration, quality of the experience, preoccupation with it, and its effects on functioning and behavior. In 1980, anxiety disorders were introduced as a distinct group in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III). The disorders retained this status in the fourth edition, the DSM-IV, and include many specific diagnoses, except for anxiety disorders related to substance abuse and those related to general medical conditions.

Biological, Psychological and Trauma

Anxiety disorders do not have one specific cause. Rather, these disorders develop because of a combination of factors, including biological causes, family history, psychological issues, and stressful or traumatic life events.

Biological causes of anxiety include problems with the regulation of neurotransmitters, the chemicals in the brain that transmit signals between cells. Serotonin, norepinephrine and gamma-aminobutyric acid (GABA) are the neurotransmitters involved with anxiety. Serotonin regulates appetite, sleep, mood, aggression, impulses, body temperature and pain. Norepinephrine is connected to the fight or flight response and regulates sleep, mood and blood pressure. GABA aids in promoting relaxation and sleep, and in controlling over excitation.

Brain-imaging techniques have indicated abnormal activity of specific areas of the brain in individuals with anxiety disorders. Abnormalities in cerebral blood flow and metabolism, for instance, along with frontal, occipital, and temporal lobe anomalies have been found in people diagnosed with these disorders. Higher than normal levels of activity in the locus ceruleus and the median raphe nucleus, with a high number of norepinephrine and serotonin neurons respectively seems to be linked with the development of panic attacks. Researchers, however, do not know yet how these abnormalities are linked to anxiety. Lastly, activity in the norepinephrine systems of the body and brain produce physical symptoms of anxiety (blushing, perspiring, and experiencing palpitations) and have been associated with the flashbacks of post traumatic stress disorder.

Family studies, twin studies, and genetic linkage studies have confirmed the role of genetics in the etiology of anxiety disorders. Individuals are more likely to have an anxiety disorder if they have or have had a relative with one. Close to 50% of people with a panic disorder have at least one relative with the disorder.

Psychological factors that contribute to the etiology of anxiety disorders are usually broken down into the cognitive, behavioral, and psychodynamic theories.

  • The cognitive theory emphasizes the role of dangers or threats and an individual’s ability to cope with them. People with anxiety disorders often overestimate danger and its potential consequences.

  • The behavioral theory, based on the learning theory, suggests that people acquire fear or anxiety by associating these feelings during stressful or traumatic events with specific cues, such as a place or a sound. Fear and anxiety are learned and felt again and again when these cues reoccur. This learned behavior becomes immediate, automatic, and out of conscious control.

  • The psychodynamic theory is now considered controversial and states that anxiety results from conflicts between sexual and aggressive urges and the defenses used against these urges.

Finally, stressful or traumatic life events, such as illness, divorce, or any type of abuse, can cause the development of anxiety disorders. These circumstances have a greater chance of creating anxiety disorders when biological causes and a family history of anxiety are present. The severity of anxiety disorders can depend on the type of stress or trauma and the duration of it.


Centre for Addiction and Mental Health. “What causes anxiety disorders.”

Starcevic, Vladen. Anxiety Disorders in Adults: A Clinical Guide. Oxford University Press, USA, 2004