Young women who grow up in cities or move there from rural areas are five times more likely to suffer from bulimia.

A scientific study has revealed a startling correlation between cases of the eating disorder, in which sufferers secretly gorge and purge themselves, and the environment in which they live. Researchers found that whereas cases of anorexia, a closely related disorder, appeared to occur at random, bulimics were more than twice as likely to be in urban environments, increasing to five times in large cities.

The distress of suffering from bulimia, which most commonly affects teenage girls and young women, trapping them in a routine of binge-eating and vomiting, was most famously described by Diana, Princess of Wales. She grew up in the country, at the Spencers’ family home of Althorp, Northamptonshire, and moved to London as a teenager.

A number of mental disorders, including schizophrenia, psychosis and depression, have previously been shown to be linked with urban life.

To test whether bulimia had a link with city life, a Dutch team, led by Hans Hoek, of Gröningen University Department of Psychiatry, looked at ten years’ data from family doctors in the Netherlands. They listed every case of anorexia or bulimia diagnosed by 63 GP practices between the late 1980s and the late 1990s. The sample represented about 1 per cent of the population.

Dr Hoek, who was the first to suggest a possible link between bulimia and city life in 1995, and colleagues, led by Gabrielle Van Son, report in the British Journal of Psychiatry that 113 cases of anorexia were recorded, and 110 of bulimia. Almost all were in young women. Anorexia tended to be diagnosed at an earlier age (22, on average) than did bulimia (27).

For anorexia, there was little obvious link with where the women lived. The rate was lowest in big cities. But bulimia showed a completely different pattern. In rural areas, only seven out of every 100,000 women had it diagnosed, rising to 16.7 per 100,000 in urban areas and 25.5 per 100,000 in large cities (those with more than 100,000 people).

The researchers came up with two possible explanations: first, that women who suffer from bulimia tend to migrate to cities. They may well have had the condition beforehand, but it becomes apparent only when they leave home and seek medical advice. This explanation would be supported by bulimia tending to be diagnosed when women are older. But the pattern persisted when age was taken into account.

The second explanation relates to opportunity. It may be easier to be bulimic in cities where food supplies are plentiful, and where anonymity means that unusual behaviour is often undetected.

Bulimia, relatively rare before 1970, showed a sudden sharp rise after 1980. This suggests that either psychiatrists had failed to recognise it before, or that it did not exist.

Historical searches have failed to find evidence of bulimia, which does suggest that it is a product of today’s cultural environment. If so, it is plausible to suggest that whatever is responsible, it is found more prominently in cities than in rural areas.

The late Princess’s decision to describe her battle with bulimia has been credited with a significant decrease in severe cases. A recent study by the Institute of Psychiatry in London showed that reported cases of the illness rose to 60,000 after the Princess’s revelation. Since she first spoke of it in 1994, the number has almost halved — a trend attributed to the “Diana effect” that persuaded sufferers to seek treatment.

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