If you had lived in Japan for the last five years, you would know by now that your kokoro is at risk of coming down with a cold. Your kokoro is not part of your respiratory system. It is not a member of your family. Its treatment lies well beyond the bailiwick of your average ear, nose and throat doctor. Your kokoro is your soul, and the notion that it can catch cold (kokoro no kaze) was introduced to Japan by the pharmaceutical industry to explain mild depression to a country that almost never discussed it.

Talking about depression in Japanese has always been a fundamentally different undertaking than talking about it in English. In our language, the word for depression is remarkably versatile. It can describe dips in landscapes, economies or moods. It can refer to a devastating psychiatric condition or a fleeting response to the Cubs losing the pennant. It can be subdivided almost endlessly: major, minor, agitated, anxious, bipolar, unipolar, postpartum, premenstrual.

But in Japanese, the word for depression (utsubyo) traditionally referred only to major or manic depressive disorders and was seldom heard outside psychiatric circles. To talk about feelings, people relied on the word ki or ''vital energy.'' A literal translation of Japanese synonyms for sorrow reads, to Westerners, like the kind of emotional troubles that might befall a kitchen sink: ki ga fusagu, sadness because your ki is blocked; ki ga omoi, sadness because your ki is sluggish; ki ga meiru, sadness because your ki is leaking.

Inside every neologism lies a compact history of cultural change -- think McJobs, metrosexuals, the blogosphere. In Japan, the coining of kokoro no kaze marked a sea change in people's thinking about depression. That transformation was triggered by the pharmaceutical industry's other contribution to Japan in 1999: along with providing a catchy slogan for mild depression, the industry provided a cure: modern antidepressants. More than a decade ago, Peter Kramer chronicled the capacity of those drugs to reshape the cultural landscape in ''Listening to Prozac.'' But back then the culture they reshaped was the culture that had shaped them. Now, a huge campaign by the pharmaceutical industry is publicizing mild depression, which most Japanese didn't realize existed until recently. Japan has become a proving ground for what we stand to gain and lose by the global expansion of Western psychopharmacology.

Certainly, Japan is a compelling candidate for a mental health makeover. Serious mental illness has long been inadequately addressed there. The suicide rate is more than twice that of the United States. The average hospitalization for mental illness lasts 390 days, compared with the American average of less than 10. Until recently, depression was regarded in much the same light as schizophrenia, and treatment was available almost exclusively in institutions. There was no such thing as ''mild'' depression. Talk therapy was rare (and remains so), and quasi-official policy dissuaded open discussion. ''The Ministry of Health considered 'depression' a bad word,'' Yukio Saito, who helped found Japan's national mental health hotline in 1971, said. For decades, Saito's requests to post hotline ads in public places were routinely denied.

Last year, in a volte-face that reflects the shifting cultural tides of the last five years, the Ministry of Health launched a committee to help educate the public about depression. The actress Nana Kinomi talked publicly about her postmenopausal depression in 2000. Other celebrities followed suit. And last month, the Imperial Household Agency acknowledged that Crown Princess Masako is on antidepressants and in counseling for depression and an ''adjustment disorder.''

Over the past five years, according to the Japanese Bookstore Association, 177 books about depression have been published, compared with a mere 27 from 1990 to 1995. Earlier this month, the country's most popular online bulletin board, Channel 2, carried 713 conversation threads about depression -- more than music (582) or food (691) and almost as many as romance (716).

Depression has gone from bad word to buzzword. ''The media mention depression almost every week,'' said Yutaka Ono, a psychiatrist and professor at Keio University and one of Japan's leading depression experts. People have even come to his office with newspaper in hand, he said, and asked if what they have is depression. Ono has been practicing for 25 years, but, he said, the number of patients who have consulted him about mild depression has surged in the last 4 or 5. Most Japanese epidemiological data doesn't differentiate between degrees of depression, but the Ministry of Mental Health and the leading psychiatrists with whom I spoke agree that mild depression accounts for the vast majority of new cases -- of which there are a staggering number. According to IMS Health, a company that tracks global health care and pharmaceutical information, depression-related doctor vists in Japan increased 46 percent from 1999 to 2003.

Disease rates typically increase because more people get sick or because diagnosis and reporting improve. But neither explanation fully accounts for the rise in mild depression in Japan. ''There's no question in my mind that severe clinical depression is a real disease,'' said Arthur Kleinman, a psychiatry professor, chairman of Harvard's anthropology department and co-editor of the definitive work ''Culture and Depression.'' ''I could take you all over the world, and you would have no difficulty recognizing severely depressed people in completely different settings. But mild depression is a totally different kettle of fish. It allows us to relabel as depression an enormous number of things.''

As the idea of mild depression has gained traction in Japan, it may be that more people haven't gotten sick; they have simply come to define what's ailing them as a disease. Mild depression is not contagious, but it can be considered, in the root sense of the word, communicable -- and for the last five years, the pharmaceutical industry and the media have communicated one consistent message: your suffering might be a sickness. Your leaky vital energy, like your runny nose, might respond to drugs.

Looking back, Naoya Mitake thinks he might have first experienced depression while in college. ''I was about to graduate, and my friends had all been hired by Japanese companies,'' he recalled. ''I couldn't imagine doing that, but I didn't know what else to do.'' He felt incompetent and worthless, unable to make decisions about his future. He might have been depressed back then, but, he said, ''the word never came to mind.''

Mitake, now 39, steered clear of corporate Japan and instead became an associate professor of comparative politics at Komazawa University. In 2001, he consulted a doctor about his longstanding battles with insomnia and fatigue. The doctor prescribed antidepressants -- a common treatment for insomnia -- but Mitake's sleep didn't improve. (People on antidepressants frequently have to try different pills and dosages before finding an effective treatment.) Meanwhile, Mitake became increasingly anxious, frightened and sad. He stopped taking the first set of antidepressants, and his problems persisted. This time, he said, he knew he was ''extremely depressed.''

Mitake is handsome, warm and articulate. He talked about his experiences with an appealing blend of curiosity and tranquillity, although the emotions he described were far from tranquil. ''I'd wake up in the middle of the night with this strange, strong anxiety,'' he remembered. ''I couldn't be alone. I felt too afraid. I couldn't teach my classes anymore.''

Three months after his mood plummeted, he turned to antidepressants again and felt considerably better but not perfect. For almost two years, he cycled through various pills, with his melancholy waxing and waning. It wasn't until the summer of 2003, when he accidentally discovered a nonmedical treatment of his own, that his depression lifted.

In the Diagnostic and Statistical Manual -- the American Psychiatric Association's compendium of mental disorders -- depression is divided into discrete categories. In reality, though, there is no discernible line where moodiness crosses over into mild depression, or mild depression into severe. Moreover, mild depression does not feel mild to those who experience it. When I asked Mitake if his soul had a cold, he laughed, then paused and said he shouldn't have laughed. ''The phrase did some good. It changed people's perception and made depression easier to talk about.''

In a country famous for its reticence, that is no small achievement -- especially since talking about depression is one effective way to treat it. But counseling is still rare in Japan; in books and speeches, Yutaka Ono has tried to encourage people to discuss their depression with a professional, but, he said, psychotherapy has been far slower to catch on than medication. The current idiom also has its limits: Mitake, for one, said he never uses the expression kokoro no kaze. ''Maybe for some people depression is like a cold,'' he said. ''If so, their colds are a lot worse than mine. Or my depression is a lot worse than theirs.''

For 1,500 years of Japanese history, Buddhism has encouraged the acceptance of sadness and discouraged the pursuit of happiness -- a fundamental distinction between Western and Eastern attitudes. The first of Buddhism's four central precepts is: suffering exists. Because sickness and death are inevitable, resisting them brings more misery, not less. ''Nature shows us that life is sadness, that everything dies or ends,'' Hayao Kawai, a clinical psychologist who is now Japan's commissioner of cultural affairs, said. ''Our mythology repeats that; we do not have stories where anyone lives happily ever after.'' Happiness is nearly always fleeting in Japanese art and literature. That bittersweet aesthetic, known as aware, prizes melancholy as a sign of sensitivity.

This traditional way of thinking about suffering helps to explain why mild depression was never considered a disease. ''Melancholia, sensitivity, fragility -- these are not negative things in a Japanese context,'' Tooru Takahashi, a psychiatrist who worked for Japan's National Institute of Mental Health for 30 years, explained. ''It never occurred to us that we should try to remove them, because it never occurred to us that they were bad.''

The medical model of depression, by contrast, sees suffering as pathological and prescribes a pill in response. That outlook is partly pragmatic: call depression a disease and health insurance covers its treatment.

Patient advocates also argue that reclassifying depression as a disease helps to diminish its stigma. But probably most important, the pharmaceutical industry has the financial incentive to recast moods as medical problems, creating what Kleinman calls ''a pharmacology of remorse and regret.'' It is, Kleinman said, ''one of the most powerful aspects of globalization, and Japan is at its leading edge.''

In the late 1980's, Eli Lilly decided against selling Prozac in Japan after market research there revealed virtually no demand for antidepressants. Throughout the 90's, when Prozac and other selective serotonin reuptake inhibitors, or S.S.R.I.'s, were traveling the strange road from chemical compound to cultural phenomenon in the West, the drugs and the disease alike remained virtually unknown in Japan.

Then, in 1999, a Japanese company, Meiji Seika Kaisha, began selling the S.S.R.I. Depromel. Meiji was among the first users of the phrase kokoro no kaze. The next year, GlaxoSmithKline -- maker of the antidepressant Paxil -- followed Meiji into the market. Koji Nakagawa, GlaxoSmithKline's product manager for Paxil, explained: ''When other pharmaceutical companies were giving up on developing antidepressants in Japan, we went ahead for a very simple reason: the successful marketing in the United States and Europe.''

Direct-to-consumer drug advertising is illegal in Japan, so the company relied on educational campaigns targeting mild depression. As Nakagawa put it: ''People didn't know they were suffering from a disease. We felt it was important to reach out to them.'' So the company formulated a tripartite message: ''Depression is a disease that anyone can get. It can be cured by medicine. Early detection is important.''

Like the Bush administration, GlaxoSmithKline has spent the last four years staying relentlessly on-message. Its 1,350 Paxil-promoting medical representatives visit selected doctors an average of twice a week. Awareness campaigns teach general practitioners and the public to recognize the following symptoms of depression (the translation is the company's): ''head feels heavy, cannot sleep, stiff shoulders, backache, tired and lazy, no appetite, not intrigued, feel depressed.''

The psychiatrist Yutaka Ono advocates raising awareness about depression, but GlaxoSmithKline's marketing made him uncomfortable: ''They ran a very intense campaign about mild depression where a beautiful young lady comes out all smiles and says, 'I went to a doctor and now I'm happy.' You know, depression is not that easy. And if it is that easy, it might not be depression.''

Whatever misgivings Ono and other doctors may have about the medicalization of mild depression, it has been a resounding financial success. As one psychiatrist, Kenji Kitanishi, noted wryly, ''Japanese psychiatry is in the bubble economy now.'' Between 1998 and 2003, sales of antidepressants in Japan quintupled, according to IMS Health. GlaxoSmithKline alone saw its sales of Paxil increase from $108 million in 2001 to $298 million in 2003. According to the company, during one seven-month ad campaign it ran last year, 110,000 people in a population of 127 million consulted their doctors about depression.

In late 2001, one of those people was Mitake. ''From the things I'd read, I knew about these chemicals in the brain, serotonin and so forth,'' Mitake said. ''And I thought, O.K., this is a chemical phenomenon, so it needs to be cured by a chemical substance.'' In fact, no one understands the etiology of depression, and the role serotonin plays is ambiguous. Ask people with mild depression to explain its origins, and most will offer autobiography, not biochemistry: difficult families, dissolved relationships, demanding jobs. Japanese mental health specialists consistently cite the collapse of the bubble economy and disintegrating social structures as major factors in the nation's soaring depression rates.

The idea that depression is a neurochemical malfunction dodges a fundamental chicken-and-egg problem. Screwy neurochemistry can cause depression, but depression can also wreak havoc on your neurochemistry. Likewise, research has shown brain chemistry can change in response to any number of interventions: medication, talk therapy, exercise, prayer. The question, then, isn't whether depression is a biochemical phenomenon; it is. So is the act of formulating a thought. So, in a sense, is sorrow. The question is, What do we gain, and what do we lose, by understanding the darker acts of our brains as diseases?

One side effect of the antidepressants Mitake was taking was weight gain, so in August 2003 he went on a fasting retreat in the mountains. He thought he'd do some reading, but after the fourth day, he recounted: ''You can't even think. You just kind of lie there.'' Toward the end of his fast, Mitake went to a hot spring. ''There I was, totally naked with this breeze blowing and the sun shining, and suddenly I started to feel better,'' he recalled. Mitake credits the fast with ending his depression. ''It's like because I couldn't think for a while, the cycle just broke. All those negative feelings were gone.'' His depression hasn't returned, although on his doctor's advice, he continued to take antidepressants until last month.

Mitake was quick to sound a cautionary note: ''I don't dare tell my friends with depression, 'Oh, you should go fast.' I tell them to find a good doctor and take medication as prescribed. I really believe the fast is what worked in my case, but I'd never recommend it as a cure.''

Andrew Solomon, author of ''The Noonday Demon,'' champions antidepressants, but even he ultimately concludes that the best cure is the one you believe in. ''If you have cancer and try an exotic treatment and then think you are better, you may well be wrong,'' he writes. ''If you have depression and try an exotic treatment and think you are better, you are better.'' Yet the medicalization of depression makes it difficult to believe in any treatment but medicine. Rather than expanding options for care for those who suffer, the globalization of psychopharmacology may ultimately sow a monocrop of ideas about health and sickness.

Writing about changing understandings of depression in other countries risks romanticizing suffering and other cultures. But not writing about them contributes to a kind of silence already evident in Japan. ''There is this almost invisible pressure that makes it difficult to freely raise questions,'' Saito, one of the founders of Japan's mental health hotline, noted. ''I find myself doubting whether medicalization is a good trend. But being in the position I'm in, needing some support from the medical system, I don't usually make comments like this.''

Thomas Hardy once noted, ''What we gain by science is, after all, sadness.'' He meant the more we learn about nature, the crueler it seems and the less individual experience matters. The century since he wrote has seen stunning technological advances, but we haven't made much progress figuring out how to integrate science with other ways of understanding what it means to be human. These days, we may lose even sadness.

Photo (Photograph by James Whitlow Delano/Redux)