Roxanne Bachowski spent 15 years convinced she was deathly ill. The mother of two regularly experienced frightening episodes of shortness of breath and dizziness, with her heart pounding and eyes dilated. She made hundreds of trips to doctors and was given countless tests, but medical science could find nothing wrong with her. Once, she recalled, she snuck into a morgue to be among the dead, whom she longed to join.

Almost two years ago, after being rushed to Suburban Hospital in Bethesda by ambulance, she found her diagnosis: she had been suffering for years from panic attacks.

"I had five MRIs, was on the treadmill a dozen times--there wasn't a test I didn't have," said Bachowski, who lives in Potomac. "The symptoms I was getting were real, but it took years to learn the cause, that I have a panic disorder."

Once diagnosed, she began behavioral therapy--a treatment that includes confronting the situations that trigger attacks (seeing a snake, for one), taking medications and making a pledge of "no more tests!" Bachowski, who is in her-thirties, says she can now go outside alone and can drive her car around the Beltway. She has reclaimed some, though not yet all, of her former active life.

Bachowski's experience is a familiar story. According to estimates from a national survey of people aged 15 to 54, more than 27 million Americans in that age group suffer from some form of anxiety disorder, ranging from panic attacks and phobias to obsessive-compulsive and post-traumatic stress disorders. Most involve the brain's inappropriate release of the fight-or-flight chemicals such as cortisol and adrenaline. This response, which evolved over eons to help people escape from danger, now makes millions of Americans feel seriously endangered when they are not.

What's more, anxiety disorders are often interwoven with depression, and a heated debate continues over which one comes first in patients with dual diagnoses. Studies estimate that 12 million Americans experience their anxiety disorders coupled with depression or another psychiatric ailment. Yet until recently, anxiety disorders have largely been an orphan among mental illnesses. The symptoms of anxiety disorders are generally not taught in medical school, experts complain, and diagnoses are made by exclusion--only after everything else has been ruled out. As Washington psychiatrist Brian Doyle recently put it, "Anxiety disorders get no respect."

Now a major study on the economic burden of anxiety disorders, commissioned by the Anxiety Disorders Association of America, has documented the high cost of treating--and mistreating or not treating--these mental illnesses. The results, published in this month's Journal of Clinical Psychiatry, put a national price tag of $63 billion on the direct costs and workplace losses from anxiety disorders each year.

The study, led by Paul E. Greenberg of the Analysis Group/Economics of Cambridge, Mass., and Ronald C. Kessler of the Harvard Medical School, found that more than half of the cost associated with anxiety disorders is paid to non-psychiatric hospitals, doctors and medical testing services that deal with the the symptoms of anxiety disorders but seldom address the illness itself.

"What we found is that anxiety disorders cost the health care system a lot, especially to test for symptoms that mimic other illnesses," said Kessler. "If we could find people the right treatment for their anxiety, rather than running so many tests for other diseases, it is a potential win-win situation. Doctors need to be asking, 'Might there be an emotional problem here?' "

Frequently, people suffering from anxiety come into hospitals complaining of headaches, backaches, stomach trouble and what they believe are heart attacks, Kessler said.

In the study, researchers found that only about a quarter of the people with an accurate diagnosis were receiving appropriate treatment. If more people with anxiety disorders got the right treatment, the study concluded, "a substantial portion of the overall economic burden of anxiety disorders can be avoided."

The researchers also found that in the workplace, untreated anxiety among workers resulted in increased absenteeism and lower productivity. About 10 percent of the cost of anxiety disorders, they found, came from these workplace losses.

According to coauthor Greenberg, research into anxiety disorders is increasing now that better treatments are available. "As with depression 10 years ago, the interest and attention on anxiety awareness is growing as pharmaceutical manufacturers can offer more helpful medications," he said. "But the amount of research going into anxiety disorders is still well below the amount for depression."

The Anxiety Disorders Association study was funded by nine pharmaceutical companies.

One problem in reducing the toll of this mental illness is that there is no test that can detect anxiety disorders the way health professionals can monitor blood pressure or even screen for depression. In 1993, the American Psychiatric Association brought together 12 experts to draw up a test to screen for possible panic disorders. According to psychiatrist Doyle, a member of the panel, the group ultimately could not come up with the screen.

"Given the very different clinical presentations, it was impossible to say that every patient should have an EKG or a chest X-ray or an upper and lower GI test," Doyle said. "We have the protocols to define a panic disorder, but we don't have a general tool to screen for it."

Meanwhile at the National Institute of Mental Health, research is underway to find out how the information that makes up anxiety and fear is processed by the brain and transmitted through its neurological pathways. Experiments have consistently shown physical differences in the neural brain patterns of people who suffer from anxiety disorders and those who don't.

For instance, the brain normally has two pathways for processing fearful information--a primitive one that sends threatening information quickly and another that routes the information through the more "deliberative" frontal cortex. In people suffering from post-traumatic stress disorder, researchers have found, the second pathway through the cortex is generally not activated. Researchers are hopeful this information will help with diagnosis in the future.

"Our tools aren't refined enough yet to diagnose disorders based on our neural imaging," said NIMH Director Steven Hyman. "But I think there's a high likelihood we'll be able to do this within five years."

According to Jerilyn Ross, a Washington therapist who is head of the Anxiety Disorders Association, the recognition that these disorders have biological roots has been very helpful to people with anxiety disorders.

"I tell patients their problem has a biological component, that it's as if wires in their brains have gotten crossed," Ross said. "The body is responding appropriately in releasing chemicals, but it's going off at the wrong time. It's a false alarm.

"These disorders have been so trivialized in the past--people told to 'just calm down or get over it'--that these new findings of a physical disorder have been very important," she said.

Just what causes anxiety disorders to develop is not known. Experts believe a combination of genetic makeup and childhood experiences sets the stage for many phobias and anxiety disorders.

This view, which parallels some Freudian insights into the development of personality and mental illness, has nonetheless led to some non-Freudian treatments for anxiety disorders.

Rather than looking to reveal the deep-seated origins of a person's phobia through psychoanalysis, today's cognitive behavioral therapies seek instead to address the patient's fears in more concrete and immediate ways.

Patients with a fear of heights, for instance, may be taken to upper levels of tall buildings. Bachowski with her fear of snakes gradually got to know a large one at a local pet store and ultimately allowed it to wrap itself around her.

"It's important that people know that anxiety disorders can affect very strong and active people," she said. "I come from a high-powered background, but panic attacks almost destroyed me and my family, too. I know there are a lot of other people out there like me."