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Overview of Anxiety Disorders

by John H. Greist, MD

Anxiety disorders involve a state of distressing chronic but fluctuating nervousness that is inappropriately severe for the person's circumstances.

  • Anxiety disorders can make people sweat, feel short of breath or dizzy, have a rapid heartbeat, tremble, and avoid certain situations.

  • These disorders are usually diagnosed using specific established criteria.

  • Drugs, psychotherapy, or both can substantially help most people.

Anxiety is a normal response to a threat or to psychologic stress and is experienced occasionally by everyone. Normal anxiety has its root in fear and serves an important survival function. When someone is faced with a dangerous situation, anxiety induces the fight-or-flight response. With this response, a variety of physical changes, such as increased blood flow to the heart and muscles, provide the body with the necessary energy and strength to deal with life-threatening situations, such as running from an aggressive animal or fighting off an attacker. However, when anxiety occurs at inappropriate times, occurs frequently, or is so intense and long-lasting that it interferes with a person's normal activities, it is considered a disorder.

Anxiety disorders are more common than any other category of mental health disorder and are believed to affect about 15% of adults in the United States. However, anxiety disorders often are not recognized by people who have them or by health care practitioners and consequently are seldom treated.

How Anxiety Affects Performance

The effects of anxiety on performance can be shown on a curve. As the level of anxiety increases, performance efficiency increases proportionately, but only up to a point. As anxiety increases further, performance efficiency decreases. Before the peak of the curve, anxiety is considered adaptive because it helps people prepare for a crisis and improve their functioning. Beyond the peak of the curve, anxiety is considered maladaptive because it produces distress and impairs functioning.


The causes of anxiety disorders are not fully known, but genetic factors (including a family history), environment (such as experiencing a traumatic event or stress), psychologic make-up, and physical condition may be involved. An anxiety disorder can be triggered by environmental stresses, such as the breakup of a significant relationship or exposure to a life-threatening disaster. When a person's response to stresses is inappropriate or a person is overwhelmed by events, an anxiety disorder can arise. For example, some people find speaking before a group exhilarating. But others dread it, becoming anxious with symptoms such as sweating, fear, a rapid heart rate, and tremor. Such people may avoid speaking even in a small group.

Anxiety may also be caused by a physical disorder or the use of a drug (see Anxiety Induced by Physical Disorders or Drugs). For example, an overactive thyroid or adrenal gland can cause anxiety, as can a hormone-secreting tumor called a pheochromocytoma. Drugs that can cause anxiety include corticosteroids, cocaine, amphetamines, ephedrine, and sometimes caffeine if too much is consumed. Withdrawal from alcohol or certain sedatives can also cause symptoms of an anxiety disorder. In older people, dementia may be the most common cause of anxiety.

Anxiety tends to run in families. Doctors think some of this tendency may be inherited, but some is probably learned by living with anxious people.

Did You Know...

  • Anxiety disorders are the most common type of mental health disorder.

  • People with an anxiety disorder are more likely than other people to have depression.


Anxiety can arise suddenly, as in panic, or gradually over minutes, hours, or days. Anxiety can last for any length of time, from a few seconds to years. It ranges in intensity from barely noticeable qualms to a full-blown panic attack (see Panic Attacks and Panic Disorder), which may cause shortness of breath, dizziness, an increased heart rate, and trembling (tremor).

Anxiety disorders can be so distressing and interfere so much with a person's life that they can lead to depression (see Depression). People who have an anxiety disorder (except for certain very specific phobias, such as fear of spiders) are at least twice as likely to have depression as those without an anxiety disorder. Usually, the anxiety disorder develops before depression.


The diagnosis of an anxiety disorder is based largely on symptoms. The ability to tolerate anxiety varies, and determining what constitutes abnormal anxiety can be difficult. Doctors usually use specific established criteria, based mainly on symptoms and exclusion of other causes of symptoms.

Doctors ask whether family members have had similar symptoms. A family history of an anxiety disorder (except posttraumatic stress disorder, which results from a specific event) may help doctors make the diagnosis. Doctors also do a physical examination. Blood and other tests may be done to check for disorders that can cause anxiety.


Accurate diagnosis is important because treatment varies from one anxiety disorder to another. Additionally, anxiety disorders must be distinguished from anxiety that occurs in many other mental health disorders, which involve different treatment approaches. Depending on the anxiety disorder, drug therapy or psychotherapy (such as behavioral therapy), alone or in combination, can significantly relieve the distress and dysfunction for most people.

Drugs Used to Treat Anxiety Disorders



Some Side Effects










Generalized anxiety disorder

Panic disorder

Phobic disorders

Sleepiness, impaired coordination, and slowed reaction time

May lead to drug dependence

Most commonly used type of antianxiety drug

Promote mental and physical relaxation by reducing nerve activity in the brain

Begin to work quickly, sometimes within an hour

Should not be used by people who are dependent on alcohol


Generalized anxiety disorder

Dizziness and headache

Does not cause drowsiness or interact with alcohol

Does not lead to drug dependence

May take several weeks to start working


Selective serotonin reuptake inhibitors (such as escitalopram)

Norepinephrine -serotonin reuptake inhibitors (such as duloxetine and venlafaxine)

Monoamine oxidase inhibitors

Tricyclic antidepressants (such as clomipramine)

Generalized anxiety disorder

Panic disorder

Phobic disorders

Obsessive-compulsive disorder

Posttraumatic stress disorder

*Not all of the antidepressants listed work for all of the uses that are listed.

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Drugs Mentioned In This Article

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