Did you know clinical depression may be a symptom of other mental illnesses? For example, there's a link between clinical depression and anxiety disorders. That includes such disorders as post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), panic disorder, social phobia, and generalized anxiety disorder. Together, these conditions affect millions of Americans. Fortunately, these mental illnesses can be treated effectively, and those affected can lead normal and productive lives.

What is anxiety?

Anxiety is a normal reaction to stress. However, anxiety can take on a life of its own. Then it becomes an unhealthy, generalized reaction that affects the body and mind. Symptoms can include rapid heartbeat, aches and pains, and muscle tension.

According to the National Institutes of Health, 40 million adults in the United States suffer from anxiety disorder of some type in any given year. Like depression, anxiety is thought to arise from a combination of both genetic and environmental factors.

What is an anxiety disorder?

Although anxiety is not always present in depressive disorders, most of the time it lurks beneath the surface. It generally presents itself as one of a number of symptoms within the depressive syndrome. While a depressed mood is generally the first and most important symptom in depressive disorders, in anxiety disorders, anxiety is the primary symptom. It's often the first symptom to appear, even though depression is commonly present.

There are several different types of anxiety disorder. They include:

Generalized anxiety disorder (GAD)
Obsessive-compulsive disorder (OCD)
Panic disorder -- with or without agoraphobia
Phobic disorder
Social anxiety disorder
Posttraumatic stress disorder (PTSD)

Anxiety disorders affect women twice as frequently as they do men. And many studies show that people with depression often have clinical characteristics of an anxiety disorder.

An anxiety disorder that's left untreated can cause unnecessary suffering and impairment for both the person who has it and the person's family.

What is generalized anxiety disorder (GAD)?

People with generalized anxiety disorder (GAD) are filled with greatly exaggerated worry and tension. They experience these feelings even though there is usually nothing to worry about. These individuals anticipate disaster and ruminate about their health, their finances, their relationships and family problems, or their work.

With GAD, there is excessive worry and anxiety occurring more days than not for at least six months. The person is unable to control the worry and may have other symptoms including:

Difficulty concentrating
Fatigue
Irritability
Muscle tension
Restlessness
Sleep disturbance

This anxiety disorder is not related to substance abuse or a medical condition. It occurs independently.

What is obsessive-compulsive disorder?

Obsessive-compulsive disorder, or OCD, is characterized by continuous, unwanted, and intruding thoughts that the person is unable to control. These thoughts are also accompanied by a pervasive anxiety.

Compulsive disorder refers to repeated, ritualistic behavior that often is purposeless. Nevertheless, the patient is unable to reduce or stop it. OCD is also accompanied by general anxiety. Obsessive thoughts and compulsive acts may focus around real-life problems the patient is confronting or may take on a bizarre nature.