Two-and-a-half thousand years ago, Hippocrates wrote that it was more important to know what sort of person has a disease than to know what disease a person has.

Great man that he was, today's doctors wouldn't get far with that as a priority. All sorts of people develop the same diseases, from infections to allergies, cancers and diseases of ageing or over-indulgence.

This has meant that discovering the details of a patient's character and emotional reactions have taken a back seat when we need to make a diagnosis and decide on a treatment.

It has made us very much more efficient and we are curing far more diseases than Hippocrates could ever have imagined - but from time to time there's something in the old man's philosophy.

According to the latest research review, he was surely right when it comes to one of the commonest illnesses in our society - irritable bowel syndrome (IBS).

If you don't have it yourself, you will certainly know someone who is plagued by it. It is the commonest condition to be seen in a general hospital physician's outpatients department, and it often defies all the treatments we throw at it.

Hippocrates would have been thrilled to know that the latest efforts at its treatment have turned to his ideas for the answer.

But to know why we still have to know the nature of irritable bowel, and why it produces the symptoms that it does. Everyone who has ever had a bowel upset will recognise them.

They include bloating, stomach pains, wind, changes in bowel habit - from constipation to diarrhoea and back again - often linked to emotional and physical stress. They are exactly the same bunch of symptoms you get when you have caught food poisoning.

To doctors, this combination of symptoms means that the very delicate mechanism that keeps the bowel digesting and passing on food in an orderly fashion from top to tail, so to speak, has been disturbed.

Their cause is obvious when the food you have eaten is contaminated by salmonella or one of the many other food-poisoning germs. But why do we get them when we don't have an infection?

Most of the time we don't know our gut is working hard on our behalf. We don't feel it and we only occasionally hear it - the odd rumble as the food is shunted along part of the large bowel is the worst we hear.

That's because when we are calm and relaxed the nervous system that controls the movement of food along our gut simply carries on as normal.

But when we are stressed, it goes into overdrive. Some parts of our bowel contract at the wrong time, or shut down altogether.

A discordant combination of both leads to the symptoms - the pain, the bloating, the extra gas, the loose motions or the constipation.

So how do we treat such symptoms? We can give drugs to calm down the chaos that your bowel is in. In theory that works well, but in practice they aren't as effective as they should be.

So people with irritable bowel often find that their medicines help to a degree, but don't make the symptoms vanish. They need long-term treatment, and with any powerful medicines, they then to cause side effects that may sometimes be as disturbing as the illness itself.

Here's where old Hippocrates comes in. Know the type of person who has irritable bowel, and you may be able to help them to overcome the illness with psychological training.

In today's practice that means a system called cognitive behaviour therapy. It's a way of getting patients out of their old way of thinking about things and helping them to think more positively not just about their symptoms but their whole way of approaching life and its problems.

We all have them - it's important to make sure that we cope with them in a satisfactory way that doesn't upset our nervous systems.

Last week's British Medical Journal reviewed all the current treatments for irritable bowel, and cognitive behaviour therapy came top of the list for people who are distressed by their symptoms, who are open to the idea that their symptoms may have an underlying nervous cause, and are willing to take part in the sessions.

It isn't so effective in people who are very anxious or who have symptoms every day.

Most general practices now have access to someone who can offer cognitive behaviour therapy. If you have IBS, it might be worthwhile to discuss it with your doctor or practice nurse.