Brendan I Koerner on the ugly truth about doctors, PR firms and drug companies.

Word of the hidden epidemic began spreading in spring last year. Local news reports around the United States reported that as many as 10 million Americans suffered from an unrecognised disease. Viewers were urged to watch for the symptoms: restlessness, fatigue, irritability, muscle tension, nausea, diarrhoea, and sweating, among others. Many of the segments featured soundbites from Sonja Burkett, a patient who had finally received treatment after two years trapped at home by the illness, and from Dr Jack Gorman, an esteemed psychiatrist at Columbia University.

The disease was generalised anxiety disorder (GAD), a condition that, according to the reports, left sufferers paralysed with irrational fears. Mental-health advocates called it "the forgotten illness". Print periodicals were awash with stories of young women plagued by worries over money and men. "Everything took 10 times more effort for me than it did for anyone else," one woman told the Chicago Tribune. "The thing about Gad is that worry can be a full-time job. So if you add that up with what I was doing, which was being a full-time achiever, I was exhausted, constantly exhausted."

The timing of the media frenzy was no accident. On April 16 2001, the US food and drug administration (FDA) had approved the antidepressant Paxil, made by British pharmaceutical giant GlaxoSmithKline, for the treatment of Gad. But it was a little-known ailment; according to a 1989 study, as few as 1.2% of the US population merited the diagnosis in any given year. If GlaxoSmithKline hoped to capitalise on Paxil's newapproval, it would have to raise Gad's profile.

That meant revving up the company's public-relations machinery. The widely featured quotes from Burkett were part of a "video news release" the drug maker had distributed to TV stations around the country; the footage also included the comments of Gorman, who has frequently served as a paid consultant to GlaxoSmithKline. On April 16 - the date of Paxil's approval - a patient group called freedom from fear released a telephone survey which revealed that "people with Gad spend nearly 40 hours per week, or a 'full-time job,' worrying". The survey mentioned neither GlaxoSmithKline nor Paxil, but the press contact listed was an account executive at Cohn & Wolfe, the drugmaker's PR firm.

The modus operandi of GlaxoSmithKline - marketing a disease rather than selling a drug - is typical of the post-Prozac era. "The strategy [companies] use - it's almost mechanised by now," says Dr Loren Mosher, a San Diego psychiatrist and former official at the national institute of mental health. Typically, a corporate-sponsored "disease awareness" campaign focuses on a mild psychiatric condition with a large pool of potential sufferers. Companies fund studies that prove the drug's efficacy in treating the afiction, a necessary step in obtaining FDA approval for a new use, or "indication". Prominent doctors are enlisted to publicly affirm the malady's ubiquity, then public-relations firms launch campaigns to promote the new disease, using dramatic statistics from corporate-sponsored studies. Finally, patient groups are recruited to serve as the "public face" for the condition, supplying quotes and compelling stories for the media; many of the groups are heavily subsidised by drugmakers, and some operate directly out of the offices of drug companies' PR firms.

The strategy has enabled the pharmaceutical industry to squeeze millions in additional revenue from the blockbuster drugs known as selective serotonin reuptake inhibitors (SSRIs), a family of pharmaceuticals that includes Paxil, Prozac, Zoloft, Celexa, and Luvox. Originally approved solely as antidepressants, the SSRIs are now prescribed for a wide array of previously obscure afflictions - Gad, social anxiety disorder, premenstrual dysphoric disorder, and so on. The proliferation of diagnoses has contributed to a dramatic rise in anti-depressant sales, which increased eightfold between 1990 and 2000.

For pharmaceutical companies, marketing existing drugs for new uses makes perfect sense: a new indication can be obtained in less than 18 months, compared to the eight years it takes to bring a drug from the lab to the pharmacy. Managed-care companies have also been encouraging the use of medication, rather than more costly psychotherapy, to treat problems such as anxiety and depression.

But while most health experts agree that SSRIs have revolutionised the treatment of mental illness, a growing number of critics are disturbed by the degree to which corporate-sponsored campaigns have come to define what qualifies as a mental disorder and who needs to be medicated.

When Paxil hit the market in 1993, the drug's manufacturer, then known as Smith-Kline Beecham, lagged far behind