Since then, Celia has had about three attacks a month. She does not know when they are coming. She always thinks she is going to die.

Panic attacks are not subtle, and you need no quiz to find out if you or someone you love has them. As many as five percent of American adults probably do. The defining feature of the disorder is simple: recurrent awful attacks of panic that come out of the blue, last for a few minutes, and then subside. The attacks consist of chest pain, sweating, nausea, dizziness, choking, smothering, or trembling. They are accompanied by feelings of overwhelming dread and thoughts that you are having a heart attack, that you are losing control, or that you are going crazy.

THE BIOLOGY OF PANIC

There are four questions that bear on whether a mental problem is primarily "biological" as opposed to "psychological":

Can is be induced biologically?

Is it genetically heritable?

Are specific brain functions involved?

Does a drug relieve it?

Inducing panic: Panic attacks can be created by a biological agent. For example, patients who have a history of panic attacks are hooked up to an intravenous line. Sodium lactate, a chemical that normally produces rapid, shallow breathing and heart palpitations, is slowly infused into their bloodstream. Within a few minutes, about 60 to 90 percent of these patients have a panic attack. Normal controlssubjects with no history of panic-rarely have attacks when infused with lactate.

Genetics of panic: There may be some heritability of panic. If one of two identical twins has panic attacks, 31 percent of the cotwins also have them. But if one of two fraternal twins has panic attacks, none of the cotwins are so afflicted.

Panic and the brain: The brains of people with panic disorders look somewhat unusual upon close scrutiny. Their neurochemistry shows abnormalities in the system that turns on, then dampens, fear. In a`dition, the PET scan (positron-emission tomography), a technique that looks at how much blood and oxygen different parts of the brain use, shows that patients who panic from the infusion of lactate have higher blood flow and oxygen use in relevant parts of their brain than patients who don't panic.

Drugs: Two kinds of drugs relieve panic: tricyclic antidepressants and the antianxiety drug Xanax, and both work better than placebos. Panic attacks are dampened, and sometimes even eliminated. General anxiety and depression also decrease.

Since these four questions had already been answered "yes" when Jack Rachman called, I thought the issue had already been settled. Panic disorder was simply a biological illness, a disease of the body that could be relieved only by drugs.

A few months later I was in Bethesda, Maryland, listening once again to the same four lines of biological evidence. An inconspicuous figure in a brown suit sat hunched over the table. At the first break, Jack introduced me to him-David Clark, a young psychologist from Oxford. Soon after, Clark began his address.

"Consider, if you will, an alternative theory, a cognitive theory." He reminded all of us that almost all panickers believe that they are going to die during an attack. Most commonly, they believe that they are having heart attacks. Perhaps, Clark suggested, this is more than just a mere symptom. Perhaps it is the root cause. Panic may simply be the catastrophic misinterpretation of bodily sensations.

For example, when you panic your heart starts to race. You notice this, and you see it as a possible heart attack. This makes you very anxious, which means your heart pounds more. You now notice that your heart is really pounding. You are now sure it's a heart attack. This terrifies you, and you break into a sweat, feel nauseated, short of breath--all symptoms of terror, but for you, they're confirmation of a heart attack. A full-blown panic attack is under way, and at the root of it is your misinterpretation of the symptoms of anxiety as symptoms of impending death.

I was listening closely now as Clark argued that an obvious sign of a disorder, easily dismissed as a symptom, is the disorder itself. If he was right, this was a historic occasion. All Clark had done so far, however, was to show that the four lines of evidence for a biological view of panic could fit equally well with a misinterpretation view. But Clark soon told us about a series of experiments he and his colleague Paul Salkovskis had done at Oxford.

First, they compared panic patients with patients who had other anxiety disorders and with normals. All the subjects read the following sentences aloud, but the last word was presented blurred. For example:

dying if I had palpitations, I could be excited excited

choking If I were breathless, I could be unfit unfit

When the sentences were about bodily sensations, the panic patients, but no one else, saw the catastrophic endings fastest. This showed that panic patients possess the habit of thinking Clark had postulated.