Most people experience feelings of anxiety before an important event such as a big exam, business presentation or first date. Anxiety disorders, however, are illnesses that cause people to feel frightened, distressed and uneasy for no apparent reason. Left untreated, these disorders can dramatically reduce productivity and significantly diminish an individual's quality of life.

How Common Are Anxiety Disorders?
Anxiety disorders are among the most common mental illnesses in America; more than 40 million are affected by these debilitating illnesses each year.

What Are the Different Kinds of Anxiety Disorders?
Panic Disorder
Characterized by panic attacks, sudden feelings of terror that strike repeatedly and without warning. Physical symptoms include chest pain, heart palpitations, shortness of breath, dizziness, abdominal discomfort, feelings of unreality and fear of dying. There are different types of anxiety, as follows:

• Generalized Anxiety Disorder
• Obsessive-Compulsive Disorder
• Phobia
• Post-Traumatic Stress Disorder

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Link: http://www.mentalhealthamerica.net/go/information/get-info/anxiety-disorders/anxiety-disorders/anxiety-disorders-what-you-need-to-know

Bipolar Disorder (Manic Depression)
Bipolar disorder, also known as manic depression, is an illness involving one or more episodes of serious mania and depression. The illness causes a person’s mood to swing from excessively “high” and/or irritable to sad and hopeless, with periods of a normal mood in between. More than 2 million Americans suffer from bipolar disorder.

Bipolar disorder typically begins in adolescence or early adulthood and continues throughout life. It is often not recognized as an illness and people who have it may suffer needlessly for years.

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Link: http://cms.nmha.org/index.cfm?objectid=74F71A5E-1372-4D20-C830054B471F27A0