Researchers from Harvard Medical School and Chicago University carried out a study between 2001 and 2003 in which they surveyed 9,282 adults in the US. They found that 7.3 per cent of the population could be classed as having IED because they suffered from three or more outbursts of impulsive, exaggerated aggression in one year. According to the report, the disorder typically first appears in adolescence at about the age of 14. Some might attribute such outbursts to the hormonal rush that affects us all, but researchers appear increasingly certain that the condition is real and widespread.

'The critical thing is that people who don't have this disorder aren't blowing up frequently, and are not getting into trouble for it,' said Emil Coccaro, chairman of psychiatry at the University of Chicago's medical school, and co-author of the study.

In other words, there's a difference between smashing a plate in frustration and destroying an entire room. Diagnosed cases have ranged from road rage to spousal abuse, although researchers don't uniformly imply that anyone who has done such things suffers from the condition. But the study's finding of 16 million sufferers is a number greater than for those afflicted by better-known mental illnesses such as schizophrenia and bipolar disorder. Dr Coccaro said such under-diagnosis was partly due to confusion over what IED's criteria should have been in the 1980s.

'This was because IED was conceptualised as a kind of Incredible Hulk syndrome - the person is basically fine until they go absolutely berserk,' he said. 'This is not what people are really like. People who have aggressive problems have big outbursts, and then in between, they have these smaller rumblings, which is what ruled them out in the old days.'

Jennifer Hartstein, a psychologist at New York's Montefiore Medical Centre, said that IED sufferers usually had other emotional conditions as well.

'Its symptomology can be incorporated into other diagnosis such as bipolar disorder, borderline personality disorder, attention deficit, conduct disorder,' she said. 'So there are so many other things where temporary outburst is a symptom of another disorder.'

IED sufferers are usually found to have lower levels of serotonin, a mood-regulating chemical produced by the brain. The imbalance can be treated through the use of anti-depressants such as selective serotonin reuptake inhibitors and anger-management therapy.

Yet the environment in which we live is also a major factor. 'In my work with teenagers, the cases I deal with frequently involve fights with mum and dad that become so out of control that the police have to be called in,' said Dr Hartstein. 'But there's no neat and pretty pattern of recognising it.'

Dr Coccaro regards the condition as an interaction between biology and the environment. 'We might examine people in our study who are telling us about all the aggressive stuff they're doing. They then go on vacation, come back and we find their aggression scores to be a lot lower,' he said. 'It's not because there's any change for them inside, its that all the stuff outside them isn't coming at them and they're more relaxed.'

The report therefore piques the argument as to whether applying medical science to such behaviour really solves such problems: many believe such issues to be grounded instead in the increase of social pressures linked to our ever-hectic lifestyles. There is seemingly more need to find an escape valve from the stress of modern city living.

A key issue facing researchers, therefore, is what is on the increase: the condition, or the diagnosis of it?

The majority of sufferers in the study also had other emotional disorders, or drug or alcohol problems.

Only 28 per cent had ever received treatment for anger. 'There's no way of knowing if it's on the rise. Although it's possible,' said Dr Coccaro. 'Life is crazier.'