Anxiety is a common, normal, and often useful response to life's challenges and dangers. But in people who suffer from an anxiety disorder, anxiety levels spin out of control, causing psychological and physical symptoms that interfere with normal functioning, appear even in the absence of obvious external stressors, or are clearly excessive in the face of the stressors.

Researchers believe that anxiety disorders result from hyperactivity in certain areas of the brain, perhaps related to low levels of the neurotransmitter gamma-aminobutyric acid (GABA), which is responsible for keeping activity levels of nerve cells in check. Anxiety disorders also run in families.

Despite how common it is, anxiety may be undertreated: In one study, almost 20 percent of patients visiting a primary care clinic were diagnosed with at least one anxiety disorder—but 41 percent of them were receiving no treatment.

Anxiety Symptoms

Common psychological symptoms of anxiety include

  • irritability
  • intense fear
  • worry
  • difficulty concentrating, and
  • a general "keyed up" feeling.

Physical symptoms of anxiety include

  • sweating
  • dry mouth
  • hot flashes or chills
  • dizziness
  • heart palpitations
  • muscle tension
  • trembling
  • nausea
  • restlessness

Some medical conditions and drugs can cause anxiety or produce its symptoms. Alcohol withdrawal, asthma, a heart attack, an overactive thyroid, and a deficiency in folate or vitamin B12 are examples. Drugs that might cause or mimic anxiety symptoms include bronchodilators such as ephedrine and epinephrine, psychostimulants such as methylphenidate (Ritalin), and thyroid hormone.

Publication Review By: Karen L. Swartz, M.D.

Published: 06 Mar 2011

Last Modified: 07 Oct 2014