Carol Brown is 54 now, healthy and happy. But until her early 40s, her life was one panic attack after another.
The first occurred when she was 16, in an elevator. Out of the blue, said Brown, "my heart started racing, my hands were sweating, my breathing was shallow. I thought I was going to die. I didn't tell anybody. I thought I was losing my mind. It lasted maybe a minute, maybe a minute and a half, but it was enough to begin the pattern of events."
That pattern is horribly familiar to the 2.4 million Americans who get panic attacks.
In a panic attack, a person feels a rush of fear or distress with no sense of its cause. This is often accompanied by heart palpitations, shortness of breath or "air hunger," numbness or tingling, lightheadedness, fear of going crazy, depersonalization (feeling like you are not really there), flushes, chills, nausea, sweating, trembling or shaking.
Many people rush to the hospital emergency room, fearful they are having a heart attack. And the first attack often makes a person so afraid of another one that she -- women get panic attacks more often than men -- soon avoids anything associated with it.
For Brown, who is now director of program development at the Cole Mental Health Consumer Resource Center at McLean Hospital in Belmont, Mass., that meant avoiding elevators. Then, after an attack on the highway, driving. Then the supermarket. Then agoraphobia, the fear of being trapped in any situation or place where a panic attack might happen, even situations where no attack has occurred before.
Years ago, doctors might have attributed panic attacks like Brown's to some deep psychological problem. Now they suspect biology.
"The biological hypotheses for panic disorders are based on several observations," said Dr. Srini Pillay, director of the panic disorders research program at McLean.
"Pharmacologic medications can stop panic attacks, and panic attacks can be induced by various compounds," he said. Panic attacks also occur "out of the blue, suggesting some sudden alteration in chemistry." They can also occur when a person is not anxious, and even occur during sleep, "suggesting panic attacks may be tied to biological rhythms."
Family history plays a role, Pillay noted. If you have a parent or sibling with panic attacks, you have four to eight times the normal risk of getting them, too.
In the lab, researchers have shown that panic attacks can be induced by sodium lactate or carbon dioxide, which change the acid-base balance in the brain, triggering shortness of breath, one of the hallmarks of panic attacks.
Panic attacks also respond extremely well to medications like Paxil, an SSRI (selective serotonin reuptake inhibitor), which boosts the efficacy of serotonin.
Indeed, while SSRIs are about 60 percent effective against depression, they are effective 80 percent to 90 percent of the time in panic disorder, noted Dr. Alexander Neumeister, an associate professor at the Yale University School of Medicine.
Brown can vouch for that: When she began taking Paxil 12 years ago, her panic attacks vanished.
Panic attacks also seem to occur in people who have overly sensitive "suffocation alarm" systems that cause the brain to perceive a shortage of oxygen when there is none.
These alarm signals, generated in the brain and in special receptors called carotid bodies in the large arteries in the neck, have a "periodic tendency to get fired off too easily and to misinterpret ordinary fluctuations as signals of suffocation," said Dr. Donald Klein, a professor of psychiatry at Columbia University Medical Center who coined the term "panic attack" more than 40 years ago.
"In panic attacks," he said, "there is this acute sense of 'air hunger,' of struggling to breathe, which is not part of normal fear."
Moreover, scientists are closing in on the brain regions that may be involved in panic attacks. In a study published this year, researchers using PET scans showed for the first time that people who get panic attacks have one-third fewer of a certain kind of serotonin receptor in their brains. Serotonin is a key regulator of mood.
In people with panic attacks, five areas of the brain showed up as deficient in serotonin receptors, said Yale's Neumeister, the leader of that study. "I think that people are born with this reduction" in receptors, he said, while other factors subsequently "contribute to the fact that they develop symptoms."
The good news: Terrifying as they are, panic attacks are not inherently harmful and rarely last more than a few minutes, although they can lead to dysfunctional behavior such as drinking, avoiding normal activities and unnecessary visits to the ER.
"Anywhere from 60 to 80 percent of people with panic attacks are vastly improved by cognitive behavioral therapy or medications or both," said Dr. Chris Hayward, associate professor of behavioral sciences and psychiatry at Stanford University School of Medicine.