Is it possible that the magnetic therapy used by physicians in ancient Egypt to keep their young queen healthy does have a positive effect?
Not so long ago, magnetic therapy was pretty much shunned by mainstream medicine, dismissed as ineffective and, even worse, condemned as quackery.
Any benefits it might have, said the sceptics, could be explained by the placebo effect: patients believed that it worked, so it did.
But there is now mounting evidence that magnetic therapy can be effective.
More than 300 research teams around the world, at institutions such as Imperial College London, and California, Yale and Harvard Universities, have found evidence of positive effects.
It has been shown to work in conditions as diverse as arthritis, depression, incontinence, wound healing, epilepsy and spinal injuries, and is being investigated as a treatment for many more, including cancer, migraine and multiple sclerosis.
It can even, it is suggested, help to straighten crooked teeth, encourage bone to grow and help people who hear voices but have not responded to drug treatments.
Back in ancient Egyptian times and beyond, it is likely that the original idea of magnet therapy stemmed from the unusual effects of natural stones.
That is almost certainly why Cleopatra wore a naturally magnetic lodestone on her forehead to slow down the ageing process.
Before and since, many cultures have used magnetic therapy, and although it has always been part of the treatment portfolio of alternative medicine, it has remained largely at the margins of mainstream medicine because of the lack of good scientific evidence that it works.
Over the years, one or two good studies have surfaced hinting that something might be happening as a result of magnetic therapy, but the real turning point came when gold-standard, double-blind clinical trials, in which no one knows who is being treated with what, began to support some of the earlier claims.
There are two main ways of using magnets in medicine. The high-tech way is magnetic stimulation of the brain. The more traditional technique uses other types of magnet to stimulate specific areas of the body. There is now evidence that both approaches work in different ways for different conditions.
One of the landmark studies for the high-tech way has come from the Technion-Israel Institute of Technology, which showed that magnetic stimulation of the brain eases severe depression.
After two weeks of treatment, half of the patients showed a 50 per cent improvement in symptoms. Half the patients also had no need for further treatment with electroconvulsive therapy (ECT), and all those who had been given a dummy treatment did need it. "Our findings are very exciting since they provide clear evidence for the effectiveness of magnetic therapy, at least over the short term," says Dr Ehud Klein.
In a study at the Medical University of South Carolina, 20 depressed patients, who had not been helped by medication, had the treatment for 20 minutes a day for two weeks, and 10 had a magnet applied to their scalp but no treatment. In half of the 20 patients, symptoms were reduced by 50 per cent, while none of the group of 10 improved.
"This allows us, for the first time, to stimulate the brain non-invasively while the person is awake and alert," says Dr Mark George, professor of psychiatry at the university.
The technique, transcranial magnetic stimulation or TMS, works on the principle that the brain can be manipulated by small electric currents because brain cells communicate with each other and pass instructions by pulses of electricity.
"We can demonstrate it quite easily," says Dr Declan McLoughlin, a consultant psychiatrist at the Institute of Psychiatry in London.
"For example, if I were to take a magnetic coil and move it over parts of the brain that control the movement of body parts, I could make the little finger, then the middle finger, and then the thumb move."
The trick with TMS is to set up the fields over the particular area of the brain that needs retuning. It is known from the results of scanning patients with depression that there is reduced activity and blood flow in the left frontal lobe, an area of the brain above the forehead that is involved in thinking and planning.
In the therapy, a wire coil is held close to the patient's scalp above the left frontal lobe to produce a magnetic field that passes through the skull and into the brain to get activity up to normal levels.
At Imperial College, they have used the same kind of approach in people with incomplete spinal-cord injuries, leading to improvements in their ability to move muscles and limbs, and feel sensations. In the therapy, an electromagnet is put over the cerebral cortex.
"The [electromagnet's] repeated signals may work a bit like physiotherapy, but instead of repeating a physical task, the machine activates the surviving nerves to strengthen their connections," says Imperial's Dr Nick Davey.
The same high-tech approach has been used successfully, too, in cases of epilepsy and schizophrenia.
Yale researchers used magnetic stimulation on patients who had been hearing voices. Researchers say 70 per cent of such patients appear to benefit from TMS for up to a year, sometimes more.
Other forms of magnetic therapy are applied directly to the problem area. At Harvard University, patients with osteoarthritis were given high-strength magnet or dummy sleeves for their knees, which they wore for six hours a day, for six weeks.
The researchers found the beneficial effects of the magnetic sleeve began to kick in after four hours, with a sevenfold difference between patients who had the real sleeve and those who had the sham device.
The team ruled out placebo effects because 77 per cent of the people who had the dummy treatment believed they had had the real thing.
Researchers at the Peninsula Medical School in Plymouth also found that osteoarthritis pain was helped by wearing a standard magnetic bracelet compared to a dummy one.
For a study at the University of Washington, researchers put a magnet on the shoulder of patients who had suffered chronic pain for many years as a result of spinal-cord injury. After one hour, pain levels halved.
The researchers in this last study said the therapy might work by the magnet acting on the nerves. But just how this laying-on of magnets works is still not clear. One theory is that it has some kind of impact on the blood, and research in North Carolina with animals shows blood flow is stimulated by the movement of magnetic fields through tissue.
Other theories suggest that magnet therapy changes skin temperature; has an effect on iron in the blood and improves oxygenation of the blood; alters the pH balance; improves electrical conductivity of cells; or stimulates new cell growth.
Researchers in Canada suggest it works by stimulating new cartilage cells to grow.
* Conditions which some studies suggest may be helped by magnetic therapy: arthritis, depression, incontinence, healing wounds, epilepsy.
* How it works. Unclear - among the theories: by stimulating nerves, encouraging blood flow, raising blood oxygen levels, making cartilage cells grow.