Anyone who is waiting for important news or living in an unpredictable situation quite sensibly feels anxiety, a general state of apprehension or psychological tension. And anyone who is in a dangerous and unfamiliar situation, such as making a first parachute jump or facing a peevish python, quite sensibly feels flat-out fear. In the short run, these emotions are adaptive because they energize us to cope with danger. They ensure that we don't make that first jump without knowing how to operate the parachute, and that we get away from that snake as fast as we can.

But sometimes fear and anxiety become detached from any actual danger, or these feelings continue even when danger and uncertainty are past. The result may be generalized anxiety disorder, marked by long-lasting feelings of apprehension and doom; panic attacks, short-lived but intense feelings of anxiety; or phobias, excessive fears of specific things or situations.

The chief characteristic of generalized anxiety disorder is excessive, uncontrollable anxiety or worry—a feeling of foreboding and dread—that occurs on a majority of days during a 6-month period and that is not brought on by physical causes such as disease, drugs, or drinking too much coffee.

Some people suffer from generalized anxiety disorder without having lived through any specific anxiety-producing event. They may have a genetic predisposition to experience its symptoms—sweaty palms, a racing heart, shortness of breath—when they are in unfamiliar or uncontrollable situations. Genes may also be involved in causing abnormalities in the amygdala, the core structure for the acquisition of fear, and in the prefrontal cortex, which is associated with the ability to realize when danger has passed (Lonsdorf et al., 2009). But anxiety disorders may also stem from experience: Some chronically anxious people have a history, starting in childhood, of being unable to control or predict their environments (Barlow, 2000; Mineka & Zinbarg, 2006). Whatever the origin of generalized anxiety disorder, its sufferers have mental biases in the way they attend to and process threatening information. They perceive everything as an opportunity for disaster, a cognitive habit that fuels their anxiety and keeps it bubbling along (Boswell et al., 2013; Mitte, 2008). Learn more about anxiety disorders by watching the video Living With a Disorder 1.

Are you afraid of bugs, snakes, or dogs? Are you vaguely uncomfortable or so afraid that you can't stand to be around one? A phobia is an exaggerated fear of a specific situation, activity, or thing. Some common phobias—such as fear of snakes, insects, heights (acrophobia), or being trapped in enclosed spaces (claustrophobia)—may have evolved to be easily acquired in human beings because these fears reflected real dangers for the species. Some fears, as of the number 13 (triskaidekaphobia), may reflect idiosyncratic experiences or cultural traditions. Whatever its source, a true phobia is frightening and often incapacitating for its sufferer. It is not just a tendency to say “ugh” at tarantulas or skip the snake display at the zoo.

People who have a social phobia become extremely anxious in situations in which they will be observed by others—eating in a restaurant, speaking in public, having to perform for an audience. They worry that they will do or say something that will be excruciatingly embarrassing and that other people will laugh at them or reject them. These phobias are more severe forms of the occasional shyness and social anxiety that everyone experiences. For people with a social phobia, the mere thought of being in a new situation with unfamiliar people is scary enough to cause sweating, trembling, nausea, and an overwhelming feeling of inadequacy. So they don't go, increasing their isolation and imagined fears.

By far the most disabling fear disorder is agoraphobia. In ancient Greece, the agora was the social, political, business, and religious center of town, the public meeting place away from home. The fundamental fear in agoraphobia is panic and its imagined disastrous consequences—being trapped in a public place, where escape might be difficult or where help might be unavailable. Individuals with agoraphobia report many specific fears—of being in a crowded movie theater, driving in traffic or tunnels, or going to parties—but the underlying fear is of being away from a safe place, usually home, or a safe person, usually a parent or partner.

Agoraphobia typically begins with a panic attack that seems to have no cause. The attack is so unexpected and scary that the agoraphobic-to-be begins to avoid situations that he or she thinks may provoke another one. A woman we know had a panic attack while driving on a freeway. This was a perfectly normal posttraumatic response to the suicide of her husband a few weeks earlier. But thereafter she avoided freeways, as if the freeway, and not the suicide, had caused the attack. Because so many of the actions associated with agoraphobia arise as a mistaken effort to avoid a panic attack, psychologists regard agoraphobia as a “fear of fear” rather than simply a fear of places.