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Narrator: Anxiety is a familiar emotion to all of us. Whether it's peering down from a ledge or managing our finances, any one of us might feel anxious. Although it is unpleasant, anxiety is sometimes helpful. When it alerts you to a realistic threat, anxiety is adaptive and normal. Anxiety about your grades may motivate you to study harder.

Joseph Ledoux: Anxiety is a disease of worry. I mean, we all have anxiety, right? There's normal anxiety. And then there's pathological anxiety.

And the line between normal and pathological is very fuzzy. So it's hard to say when one crosses it. But in general, if your anxiety is so debilitating that it interferes with your daily life, then you have an anxiety disorder.

Narrator: Three features distinguish normal anxiety from pathological anxiety. There is a rational anxiety, which is provoked by perceived threats that are exaggerated or nonexistent.

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Narrator: There is uncontrollable anxiety, where the response is disproportionate and unrealistic. The person is aware yet unable to counteract it. And there is disruptive anxiety, where the result in behavior interferes with relationships, jobs, and other important segments of life.

Anxiety is common to many psychological disorders. But it's the main symptom in anxiety disorders. And it can manifest itself in different ways, depending on the disorder. For example, in phobia, a specific thing or experience— spiders, say, or heights— triggers a fearful response.

In panic disorder, people suffer from brief attacks of terror, often without a known cause. Some people's anxiety is longer-lasting. This condition is called GAD, generalized anxiety disorder.

People with GAD worry continually, are often tense and agitated, and are unable to identify the root cause of these feelings. Normally, anxiety quickly dissipates upon the resolution of a stressful situation. In GAD, however, when one source of worries is removed, another quickly moves in to take its place.

GAD often manifests itself physically, though doctors cannot pinpoint a root physiological cause. Long-term GAD can lead to ulcers, high blood pressure, a weakened immune systems, and other physical effects. Generalized anxiety disorder is like a dull ache, a constant, ongoing sense of distress and apprehension.

In contrast, a panic attack is a sudden episode of extreme anxiety that rapidly escalates in intensity. The most common symptoms of a panic attack are a pounding heart, rapid breathing, and a choking sensation. Accompanying the intense, escalating surge of physical arousal, are feelings of intense emotional terror.

A panic attack typically peaks within 10 minutes of onset. And then gradually subsides. When panic attacks occur frequently and unexpectedly, the person is said to be suffering from panic disorder. A panic attack can occur several times a month or not for many months and then several days in a row. It can occur after a stressful experience or not be precipitated by any discernible cause.

At times, we may feel enough anxiety to avoid making eye contact or talking with someone. Social anxiety disorder is far more debilitating than everyday shyness. People with social anxiety disorder are intensely fearful of being watched or judged by others. Even ordinary activities can cause unbearable anxiety. More severe cases are generally referred to as social phobia.

Joseph Ledoux: So fear is a response to a stimulus that's present. You're walking along the woods and there's a stake on the path, you have a fear response.

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Joseph Ledoux: Anxiety is a worry about something that's not present or that hasn't happened yet. So you worry about paying your bills. You worry about getting into college. You worry about grades. You worry about social conditions.

All of these things are things that— you might say, I'm afraid I'm going to perform poorly in this class. But really what you mean is you're anxious about performing, because it's not the particular stimulus that's triggering this, like a snake and so forth. It's more of a worry.

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Narrator: Fear becomes a phobia when it leads to an irrational desire to avoid an object or situation. In phobia, exposure to the fearful stimulus can provoke a full-fledged panic attack. For example, someone with arachnophobia may be incapacitated with terror when he or she sees a spider.

Particularly complex and debilitating is agoraphobia, which is the fear of venturing into public places. It's not the place that the person fears, but having a panic attack where it may be difficult to get help or to escape. People with agoraphobia will reduce or limit their activities to the point where they may be afraid to leave home, imprisoning themselves for weeks, months, or even years.

It is theorized that anxiety developed in early human history as a threat barometer. It gauged situations for their potential threat levels and prepared our fight-or-flight reflexes in the event of danger. Our current anxieties are rooted in the same survival instinct and the need to be alert to one's surroundings. In people with anxiety disorders, this ancient barometer seems to have gone haywire, seeing threats where there are none, and leading people to fear the worst, even in perfectly ordinary situations.

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Narrator: Anxiety remains essential to shifting the focus of our efforts to where it should be. Anxiety disorders may be a symptom of modern times. Or even though our survival is rarely threatened, the barometer has not adjusted properly to the prospect of new, reduced danger levels.

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