The moment snuck up on Joan Flechtner. She was circulating among the guests at a ceremony that she had arranged as part of her job, which she would be leaving in a few months. As long as she could stay in the the background, she was comfortable.

As long as she could leave at any time.

But then there was a hint, a stray remark. Flechtner suddenly realized "that something was happening having to do with me." As she later found out, her friends were planning a brief surprise to give her a going-away present.

She began to flit from group to group. Her breathing became difficult. Her heart was racing. She thought she might vomit. Her palms were sweating, there was a heaviness inher chest. Her legs felt like jelly.

What the well-wishers at the party could not know was that being the center of attention aroused real terror in Flechtner.

"I felt trapped. It was all of sudden at one point like someone put handcuffs on me and put down the chain fence . . . I was responding like a caged animal, trying to go from group to group, thinking all the time, 'How can I get out of this? What am I going to do next? How can I leave?' I felt very chained in. And, indeed, I left."

Flechtner is among as many as 2 million persons in the United States whose fears and anxieties, which occur in ordinary circumstances, be- come roaring monsters. Phobics believe their fears will either kill them or drive them over the brink into insanity.

Flechtner suffered from agoraphobia--fear of open spaces (from the Greek word, meaning fear of the marketplace.) For almost a decade she lived with the demon, trying to avoid panic attacks by avoiding situations she thought might provoke them. At its worst, her problem was a presence in her life, a factor that determined--and restricted--her movements. She planned her life the way a woman in a wheelchair plans her every movement to avoid physical barriers.

Elevators and public transportation had to be avoided, along with dinner parties, social events and crowds. Flechtner shopped for groceries every day, at odd hours, so she could leave the store at any moment she felt the twinge of anxiety, the first sign of a panic attack.

Almost everyone suffers from some sort of phobia, which is an extreme fear. There are social phobias-- such as fear of public speaking, of eating in public or of sexual dysfunction--which focus on fear of humiliation and embarrassment. The best known and least severe are specific phobias: fear of flying, heights, closed spaces, tunnels, dentists, thunder, lightning, insects.

Agoraphobia is the most severe of the phobias. What makes agoraphobia different from the other phobias (although in reality the fear experienced is the same) is that the agoraphobic becomes anxious when away from a safe haven. Initially, the agoraphobic associates the severe panic attacks that she (75 to 80 percent are women) experiences with a specific place or activity--standing in a grocery line, entering a crowded room, riding an elevator. In fact, the panic attack has more to do with a general level of stress, anxiety or some event in the phobic's life that has nothing to do with the place where the initial attack occurs.

Flechtner's first panic attack occurred at the end of romantic relationship when she was 20, still in college. She went in to see a psychiatrist at the student health center because she was having trouble breathing. "I felt I was walking around with a vise around my neck," she said. "I cut back distinctly, if not totally, on my socializing."

The psychiatrist, she said, was "useless," the first of a number of frustrating experiences she had in seeking treatment for her problem. "I knew he wasn't answering my question. So that was very frustrating. I didn't know that I had a phobia problem."

Subsequently, she had another relationship, which was successful. "My life got back on track emotionally," she said. When she finished college, she took a job in London, and then traveled in Europe. Her behavior became more abnormal. She found herself sitting in railroad cars as close to the exit as possible. In cities, she preferred walking to taking public transportation. She ate less and lost weight. During one train ride, while with a Swedish lawyer she had met, she became hysterical.

Without knowing it, Flechtner was well on her way to becoming a full-blown agoraphobic. The first panic attack "sensitizes" the brain and--like water running down a hill forms a gully--makes it more likely that further attacks will occur, according to Dr. David Charney, who runs the Phobia Treatment Center in Alexandria, where Flechtner was treated.

That first panic attack can strike anywhere, anytime. Almost everyone experiences this kind of "nervous discharge"--which usually lasts for less than half a minute-- and most dismiss it. The person who becomes a phobic is alarmed by the panic attack, magnifies its intensity by imagining that insanity or death is imminent. Without understanding the underlying psychological or physiological causes of the initial panic attack, the person begins to anticipate occurrence of the attack, superstitiously avoiding situations and places that he or she associates with this overwhelming fear.

Phobics are not so much afraid of the object that they associate with their problem as they are afraid of the overwhelming anxiety that sweeps over them. They experience a kind of fear of fear. Agoraphobics seem to share two characteristics, according to Dr. David Barlow, a psychologist at the State University of New York in Albany: they are "kind of high strung" and they are under some very severe life stress-- unemployment, divorce, moving, marriage or family problems.

When Flechtner returned from Europe, she took a job in Cambridge.

Since she was "definitely uncomfortable" on buses, she walked a lot, telling herself it was healthier. "People with phobias are really good at finding excuses to justify what they do," she said. She took a course in conversational French, but dropped it after two classes. "I couldn't stand being in the room," she said. "At the same time, I started having problems standing in lines." She also could not try on clothes in a store. "I had to be able to get out at the drop of a hat." She still went to the movies, but insisted on sitting near the door.

She had reached the phobic stage, where she was anticipating--and avoiding-- situations that she had come to believe would produce panic attacks. In fact, since anticipation plays a key role in phobias, her fears had a self-fulfilling quality to them.

"Then," she said, "it really started." She couldn't spend more than five minutes in a car when someone else was driving. Realizing something was wrong, she started seeing a therapist, but she's not sure she told him what was really bothering her.

"It was frightening, but also really embarrassing." She almost never went out. "If there was entertaining to be done, it had to be done at my place."

"What happens with a person with a phobia," explained phobia therapist Jonathan Crook, "is that when they go into that situation, they don't think of that (the disaster) as a possibility. They think of it as a probability. And, in some cases, it's not even a probability--it's a certainty. This feeling of impending doom that comes with the panic is so powerful."

Crook, who helped treat Flechtner, recalled working with a law enforcement officer who had a fear of restaurants and driving. "I was sitting with him in a restaurant in a Holiday Inn," Crook said. "He would have to go out and arrest people who were armed--that was part of his job. In that restaurant he said to me, 'You know, I would rather go out and make armed arrests all day long than sit with youroblem.' 15 minutes in this restaurant.' And that stuck with me . . . Most people would see somebody like that as being kind of fearless. When it comes to dealing with phobia problems, I think there's a more powerful feeling of fear than when a person knows it's a rational situation of fear."

"The physical symptom," said Flechtner, "is only part of what is a whole picture of paralyzing fear . . . The message being sent to your mind is, 'Leave, or something horrible is going to happen.' You will lose control, and that sense of losing control for each individual is horrifying."

Flechtner switched therapists. She had given up riding in elevators and subways. By then, she was getting ready to be married. She had told her fianc,e, Harry Flechtner, about her phobia problem. "What Joan worried about was that she was being 'silly,'" he recalled. "I never ever thought she was being silly. I thought she had a problem. That was part of our relationship. That was part of her."

He accepted the problem. "I understood that it was something that might change in the future. If it never changed, we could deal with it . . . These things that were causing Joan's problem did not strike me as consistent with the rest of Joan's personality. She's pretty gutsy."

Their wedding was on the glassed-in back porch of Joan's parents' house outside Boston. Every detail of the ceremony reflected her problem. She wore medium heels because high heels make running--flight--impossible. Only 19 people attended. More people might have made her feel trapped. She would have liked a church wedding, but that was "out of the question," she said, because of her phobia. The glass doors of her parents' home helped her to know that she could escape if she needed to. "If I had excused myself in the middle of the ceremony, it would not have been a big deal," she said.

Though not housebound, she had developed a classic agoraphobic behavior pattern, Crook says. Her behavior could have been pictured as a barbell, with a "safe" circle around her home, a "safe" circle around her work place and a thin ribbon connecting the two. The agoraphobic does all right as long as she stays within these two safe areas, Crook said. "God forbid anything should happen that should cause (a phobic) to deviate from either of those safe places or that thin, safe way back and forth between work and home."

Not long after the Flechtners moved to Washington, Joan began treatment at the Phobia Treatment Center in Alexandria. Her 12-week course included taking anti-depressant drugs and participating in individual and group therapy. It also included "contextual therapy": she would go with Crook into situations where she experienced panic attacks and, from having done so, would learn that she would not die or go crazy if she panicked but did not flee. By the end of the course, Flechtner had largely "recovered," the word used by her and by those who treated her use, as opposed to the word "cured"). "I had a fabulous summer," she said. "Every experience I had shied away from, I did with ease."

The root cause of her phobia does not interest Flechtner, nor should it particularly, according to Charney. He cites the case of the the phobic who undergoes years of analysis, gains an insight into the cause of the phobia but never learns how to overcome the phobia itself. At the end of such a process, Charney says, "We have a well-analyzed phobic."

Research into the causes of phobias is pursuing a number of theories. One school of thought holds that phobias are chemically induced. An- other holds that some phobics are prone to sensations that feel like anxiety attacks and lead to agoraphobia.

Women, theorizes Diane Chambless, a psychologist at American University who is setting up a phobia treatment program, may be more prone to panic attacks than men because of sexual abuse at an early age. She also cites research showing a positive correlation between the frequency of panic attacksoblem.' and dissatisfaction in marriage. Most agoraphobics are married.

Daughters of agoraphobics are more likely to have the problem than women whose mothers are not, a circumstance that might be explained genetically or environmentally.

Society may also share the blame. It is easier for a woman to hide her agoraphobia, since society easily accepts women who prefer to stay at home, Chambless said. And because society expects men to be more aggressive, more "masculine" in conquering fears, men may naturally undertake contextual therapy on their own, putting themselves into phobic situations, inducing recovery.

Apparent fearlessness-- daredevil tactics and a conscious seeking of danger--according to Charney, is often an attempt to disprove cowardice. Sky-diving (the Parachute Society of America's offices, coincidentally, are next to Charney's in Alexandria) is a "counter-phobic" sport, Charney says. He describes counter-phobics as people "who will do things that exceed prudence to prove not only that they are not cowards but that they are brave."

Part of the therapy for a recovering or recovered phobic is to consciously seek out for "practice"situations that he or she knows arouse high anxiety. For the Beltway phobic, driving on limited access highways is prescribed. The agoraphobic is encouraged to get out to shopping centers, restaurants, subways, elevators--wherever anxiety may result.

And when the anxiety comes, phobics are told, experience it, think about it, focus on it, because it will go away and you will survive. Chambless, Barlow and others report a success rate of about 70 percent in treating phobics.

To consciously enter a fear-invoking situation takes both self-discipline and courage. "It's like anyone who does anything that, for whatever reason rational or otherwise, is possibly threatening," said Flechtner, who now works at the Phobia Treatment Center, helping other phobics. "In the case of the phobic it seems almost more than life-threatening because it's not a reality, it's not controllable, and to be able to go head-long, face-forward into that, knowing what you might encounter, although obviously you've gained a lot of confidence, I think is pretty courageous."

She now can speak of her own experience with a certain amount of detachment. "I'm very proud of what I've accomplished, and I have no shame about what I was," she said. "I'm very proud that I had the problem and I recovered from it. It is a horrible problem to have and I think finally I have some sympathy and compassion for myself. I finally am able to shed a tear for what I went through."u