On a snowy Sunday in winter, I attended a conference in Cambridge, Massachusetts. The participants included a wide variety of scientists: molecular biologists, organic chemists, computer programmers, virologists, clinical researchers, and statisticians. Af- terward, a small group of us went to dinner at a local restaurant. During the meal, the conversation turned to schooling. "I transferred my eight-year-old out of public school last year," a chemist told the group. "The teacher wouldn't accommodate him. My kid is like me. When he has a problem to solve, he attacks it until it's done perfectly. He completely blocks out the world and won't let go. The teacher insisted that he couldn't spend more than the allotted time on a task. When my son wouldn't stop, the teacher concluded that he had a behavior disorder." This anecdote provoked a startlingly sympathetic response around the table: most of us, it turned out, identified with the chemist's son.

A biologist known for deciphering, atom by atom, the three-dimensional structure of complex proteins declared, "I bet I qualify for what psychiatrists call obsessive-compulsive disorder. When I'm reviewing lab data, and especially when I'm ready to send out a scientific paper, I keep thinking something is wrong. I become intensely anxious. I'll stay up all night rework- ing every graph and equation. I'm un- able to get the thought out of my head that there's a mistake. Then I find my- self checking other kinds of things. I'll go blocks away from the house and turn back to make sure the doors are locked, even though I know they are." He turned to the chemist. "I'm not sure what would have happened if I had had your son's teacher." What did it mean, I wondered as I left the restaurant, that a group of prominent scientists showed at least some traits associated with a clinical disorder during periods of high anxiety?

More and more American children are being diagnosed and medicated every year, and at younger and younger ages. If my colleagues and I were in school now, would we be considered abnormal? Current estimates hold that more than two per cent of the United States population-nearly seven million people-have or have had obsessive-compulsive disorder (O.C.D.). The American Psychiatric Association clas- sifies all known mental disorders in its Diagnostic and Statistical Manual, or D.S.M. Obsessive-compulsive disorder, which usually manifests itself in ado- lescence, is characterized by recurrent, time-consuming obsessions or compulsions that are severe enough to cause marked distress or significant impairment. Furthermore, the person recognizes that his obsessions or compulsions are excessive or unreasonable. "Obsessions" are defined in the D.S.M. as persistent thoughts, impulses, or images that are experienced as intrusive, anxiety- producing, and inappropriate. A person with such obsessions usually tries to ignore them, or to defuse them with some other thoughts or actions: this attempt defines a compulsion. You're obsessed with the thought that you didn't turn off the stove; you compulsively check to make sure it's off. (The French call O.C.D. "the doubting disease.") Other well-recognized compulsions are hand-washing, counting, or repeating special words. In its extreme form, people afflicted with O.C.D. are virtual prisoners of their compulsions- exhausted, ashamed, alienated from others. Certainly, nobody at the restaurant would have qualified for the diagnosis.

Our obsessions tended to be temporary, and connected to a productive activity, like solving an equation. We may describe ourselves as "obsessive,"but our obsessions don't control us. Although there is little information about the biological roots of the disorder-some have speculated that it can follow strep infections-recent studies indicate that people with O.C.D. have distinctive neurological circuitry. These differences are most pronounced in the limbic lobe, the caudate nucleus, and the orbital frontal cortex, the areas of the brain which participate in anxiety and automatic responses. Sophisticated brain scans show that when a potentially distressing scenario is confronted by a person without O.C.D., the brain activity in these areas barely registers on the screen; in a person with O.C.D., however, there is an intense and prolonged firing of neurons, and the scans light up like a Christmas tree. The Cambridge conference left me wondering whether scientists and other driven, detail-oriented professionals could also have distinctive neurological circuitry. Or are these mildly obsessive-compulsive people more likely to be attracted to these fields? The next day, I found myself taking another look at the familiar environment of my laboratory. In the lab-where many scientists spend ten to twelve hours each day, six to seven days a week-everything is tightly controlled. Tedious tasks demand absolute concentration, because a single error can wreck months of work.

During our lab's weekly meeting, every detail of every experiment is intensely scrutinized and challenged as we search for those hidden, threatening mistakes. Is this the natural habitat of the obsessive-compulsive? Speaking with a score of fellow-scientists throughout the week, I elic- ited anecdote after anecdote of mildly obsessive-compulsive behavior. One researcher said that when she approaches the lab to prepare for a particularly important experiment, she counts to herself and taps the wall as she walks down the corridor. Another "prefers" prime numbers, and counts to three or to seven before analyzing a sequence of DNA. A third told me that, during the month before her grant proposals are due, she repeatedly returns home to check the stove in her apartment, even though she knows that it is turned off. I also looked for survey studies on personality traits of scientists, or of children and adolescents who pursue careers in high technology. I searched for published articles in the National Library of Medicine, a repository of clinical literature; I checked listings of hundreds of popular books on Internet booksellers. Nothing specifically addressed the issue. I decided that it was time to seek professional help. "What is a disorder, anyway?" the psychologist Jane Holmes Bernstein asked me rhetorically, in an animated English accent. Holmes Bernstein is the director of the neuropsychology program at Boston's Children's Hospital, and she is an expert at behavioral assessments of children. Like most scientists, she has a healthy skepticism toward her own field: "I decided early in the game that I needed to be hit with the full battery of neuropsychiatric tests that I give to kids-that it wasn't fair unless I experienced them." One day, when she was testing a child who had been referred to her for certain learning difficulties at school, she realized that he tested exactly as she herself had. "I asked myself, 'Why am I on my side of the desk?' In my environment, I function at a high level, where it plays out adaptively." Holmes Bernstein argues that personality and behaviors can't be con- sidered separately from the particular worlds in which people live; for that reason, she de-emphasizes labels and focusses instead on the relationship between behavior and environment. "Many psychiatrists and psychologists fit kids into diagnostic boxes," she asserted. "This thinking begins in medical school. There is distinctive, intrinsic organic pathology, the patient put into a box labelled 'diabetes' or 'H.I.V.' But those boxes are not built for behavior, because behavior is influenced so strongly by its interaction with environment." She suggested that O.C.D. is a response to excess arousal-arousal in this instance meaning a neurological response to environmental stimuli. "The O.C.D. neurological circuits in the limbic system are set higher for certain stimuli and can respond faster," Holmes Bernstein said.

She pointed to recent studies at Indiana University which show that, under certain conditions, people with O.C.D. make associations between neutral as well as aversive stimuli more quickly than people without O.C.D. Holmes Bernstein believes that both this high state of arousal and the anxiety it produces may have evolutionary roots. In a prehistoric environment, those with the ability to focus and lock onto stimuli-particularly onto threatening elements in the environment-could have been better suited to escape the dangers of predators and treacherous terrain. But only to a point. "An adaptive mecha- nism can always become non-adaptive," Holmes Bernstein said. "This argument about the precise definition of O.C.D. is not just semantic, because it is the D.S.M. that dictates treatments," she went on. "Left to itself, the human animal accepts a wide range of behavior. O.C.D. becomes as much an issue of managing load in a high-stimulus environment as it is a specific neurological disorder." After leaving Holmes Bernstein, I got in touch with Anthony Rao, a clinical psychologist who has a large community-based practice in child and adolescent psychology in the Boston area. Rao's specialty is behavioral therapy, and he regularly sees children like the chemist's son, who are brought by their parents or referred by teachers. He feels that he is constantly battling against misguided attempts to diagnose children and provide generic remedies. "There is too much pathologizing of people's behaviors," he said. "In the educational system, it's one size fits all. Teachers run to labels, like A.D.D."-attention-deficit disorder-"or O.C.D., and even tell parents their children need to start taking medication."

Even among preschoolers, as a recent Journal of the American Medical Association study showed, there has been a sharp rise in the use of psychiatric medications, not only for A.D.D. but also for putative anxiety and depression. What drives all this, Rao believes, is the free-floating anxiety that parents-often successful members of the middle and upper class-foist on their children. In the instability of today's global economy, they fear that any deviation from the norm may cripple their child's future. He also believes that the currently fashionable psychiatric model-the idea that the problem is "a chemical disease of the brain"-is overly simplistic and even dangerous. These days, psychiatrists primarily treat O.C.D. with selective serotonin re-uptake inhibitors, like Prozac and Luvox, which alleviate not only its symptoms but also the anxiety and depression that often accompany it. But Rao pointed out that no one knows precisely what the long-term effects of these drugs on children will be-"especially when they are given daily for years." This approach, he contends, is treating the brain as if it were a bad kidney, when it's a far more complex organ, one which modifies itself continually. Rao was careful to stipulate that he does not categorically oppose medication. A child or an adolescent with O.C.D. who can't leave the house, or who can't sleep because he needs to repeatedly check under the bed, may greatly benefit from drugs. The prob- lem is with the larger universe of kids who are summarily labelled "abnor- mal" and medicated. In March, the White House expressed alarm at this trend, and the National Institute of Mental Health called for new studies to assess the safety and efficacy of psychoactive drug therapy for young children. "It's a different world in psychiatry now, with managed care," Rao went on. "In order for a psychiatrist to get paid, he needs to give you a D.S.M. diagnosis." Rao described a scenario that he often hears from clients about visits to psychiatrists: "Do you have worries? Do you have compulsive acts? Do you realize they are bothersome? Yes, yes, yes. Then it's boom-boom-boom, here's a prescription. You have O.C.D." Rao believes that the D.S.M. label resonates in the child's mind and among family members and friends in pejorative and embarrassing ways. "Your brain is your soul," Rao said fiercely. "You're telling a kid that there is something wrong with who he fundamentally is." Rao thinks that this excess pathologizing of people's problems is strongly driven by economics: beyond the imperatives of managed care, there is a burgeoning pharmaceutical industry that reaps huge profits from psychotropic medications. Researchers have obvious incentives to conduct drug trials that will encourage the Food and Drug Administration to approve a medication for a specific D.S.M.-defined disorder. Rao, on the other hand, attempts to temper his patients' anxieties and to redirect the compulsive behavior into more productive channels. Rao told me about a recent case of a thirteen-year-old girl whom we'll call Jan, a gifted pianist and a straight-A student.

During the past year, her performance at school had plummeted. When she began to exhibit obsessive-compulsive behavior, her parents took her to a psychiatrist, who prescribed O.C.D. medication. The drugs were of little bene- fit, and friends and teachers began to treat her as though she were seriously disturbed. The family came to Rao for a second opinion. He learned that she was haunted by thoughts of serious harm coming to her parents. To try to suppress these terrifying thoughts, she had developed a ritual of walking forward in precisely measured steps and then retracing these exact steps backward. She realized this was not rational, but she thought that walking backward would somehow undo the horrific visions of her parents in danger. "I told her that we all have terrifying thoughts, and that it doesn't mean you are crazy," Rao said. "And I explained that her precision and analytical abilities had become diverted to these irrational interior thoughts. We worked to redirect this ability outward-back to music and to math." The girl was weaned off medication and underwent behavioral therapy, focussing on the very thoughts that she found so disturbing. When her anxiety reached its apex, Rao coached her to wait a few moments before retreating to her ritual. This process was repeated, each time increasing the delay between the disturbing thoughts and the walking compulsion. Eventually, the debilitating cycle was broken. Now, when Jan feels anxious, she practices the technique that Rao taught her. Her school work is again outstanding, and she continues to play the piano.

Some studies show that such behavioral therapy can be as effective as medication in overcoming obsessions and compulsions. On the other hand, Rao pointed out, distress is an unavoidable dimension of human experience. "Struggle over suffering and pain is necessary for development," he said. "If you ignore this, or try to medicate it away, then a person doesn't develop skills to deal with life." In order to better understand a different point of view, I sought out Dr. Joseph Biederman in his office at the Massachusetts General Hospital. He is a professor of psychiatry at Harvard and chief of the joint program in pediatric psychopharmacology at Massachusetts General and McLean Hospital. Biederman rejects the contention of behavioral psychologists like Anthony Rao that children and adolescents are overdiagnosed because of the exigencies of H.M.O.s or the incentives of drug companies. Nor does he think that overzealous teachers are to blame. "The schools are not failing when they insist that a child cannot endlessly obsess over some task," he said. "That's the response of a classically narcissistic parent-the child is an extension of himself, and it's the environment that must change." Biederman also finds this response to O.C.D. naïve. "These are disruptions of normal brain functions-the diseased limbic loops are organic, not philosophical. It's a pathological state." It was not to be confused with, say, the behavior of a basketball player who mumbles things to himself before a free throw, or a pitcher who wears a special undershirt on the mound. "That's primitive, magical thinking that doesn't really interfere with functioning." Biederman illustrated his point by likening O.C.D. to high blood pressure or high cholesterol: there are well-defined limits beyond which disease occurs. "As a doctor, you see a patient with high cholesterol, and you tell him to lose weight, exercise, restrict his fat intake. Rarely can anyone do this," he said. So a doctor will prescribe medication. "Do you want to walk from Boston to New York City, or take a plane? Behavioral therapy is the most laborious form of treatment-it's walking. Medication gets you there quickly." He went on, "What we need is a screwdriver for the brain, in order to fine-tune the limbic circuit just enough so that it works efficiently and doesn't get stuck." But isn't that measurement of efficiency a highly subjective one? "Even minor illness deserves aggressive treatment," Dr. Biederman replied. "Treat early, at the first sign, when a person is still functional. Those early indicators are what I call kindling-you want to intervene when the fire is just beginning, not let it spread." After all, what he and the psychologists had in common, he said, was the goal of alleviating pain. "These peo- ple with O.C.D. are suffering, experienc- ing distress, in a state of hyperarousal. Without drugs, they can't enjoy life." I also spoke to Dr. Judith Rapoport, the chief of child psychiatry at the National Institute of Mental Health, in Bethesda, Maryland.

Dr. Rapoport, who helped bring O.C.D. to the public's attention eleven years ago with her book "The Boy Who Couldn't Stop Washing," emphasized that exact terms should be used in any discussion of the disorder. "I see the kids whose lives are wrecked by intrusive thoughts and uncontrolled compulsions," she said. "The D.S.M. criteria are carefully constructed around degree of function. "Your scientist friends are not the kind of people referred to me," Rapoport went on. She believes that these scientists more closely resemble an alternative D.S.M. diagnosis, obsessive-compulsive personality disorder (O.C.P.D.). The D.S.M. criteria here emphasize excessive devotion to work and perfectionism. A person with O.C.P.D. relentlessly engages in work, to the exclusion of social pleasures. Other experts in the field believe that the lines are more difficult to draw. Dr. John Ratey and Catherine Johnson, in their 1997 book, "Shadow Syndromes," argue that many obsessive people do not clearly fit D.S.M. criteria for O.C.D. or O.C.P.D. Further, of all the shadow syndromes, "mild obsessive-compulsive disorder is perhaps the one constellation of mood and thought society cannot do without." What links the compulsions is the fear of shame upon failing in public-the scientist who emerges from his laboratory to present his data, the pianist at each recital in the concert hall. "This is the intersection of shadow syndrome and normalcy," Ratey and Johnson argue."Obsession can drive ambition-and when it does, obsession becomes a useful quality to possess." Late one evening, I called Laurence Lasky, a nationally renowned molecu- lar biologist, to discuss my findings with him. I was not surprised to find that he was still in his lab at Genentech, a bio-technology company in the Bay Area. Lasky agreed that laboratory researchers, himself included, exhibit traits that are distributed toward the far end of the bell-shaped curve of obsessions and compulsions. "As an adolescent, I had this compulsive habit of tapping and drumming on tables, walls, my books," he told me. "It drove my mother crazy. I needed to do it to burn off my anxiety. As I grew older, it went away." Lasky still lives with anxiety, but he said that there is a huge payoff from all this tension. "There is nothing like making a discovery-the feeling of seeing some- thing in the laboratory for the first time," Lasky said. "But no good scientist I know is ever completely satisfied. What does a Nobel laureate do when he wins? He tries to win again. If you're not first, and you're not right, you're nowhere." I asked Lasky if he would want to be medicated for his anxiety. Absolutely not, he replied. "Who says advancing science has anything to do with being happy?"