Thursday, 14 November, 2002, 07:49 GMT
A group of scientists have provoked controversy by suggesting that the medical world is wrong about what causes multiple sclerosis.
It has long been thought MS is the result of immune system cells attacking and destroying the myelin protein which sheaths nerves, and helps them transmit signals.
However, New Scientist magazine reports that this view has been challenged by three neurologists.
They argue that MS is caused when support cells called astrocytes malfunction - perhaps as a result of genetic and environmental triggers.
Peter Behan and Abhijit Chaudhuri, at the University of Glasgow, and Bart Roep, of the Leiden University Medical Centre, say the autoimmune theory of MS is based on inaccurate conclusions drawn from animal experiments carried out in some cases in the 19th century.
Researchers discovered that if they injected nerve or brain tissue into an animal, its immune system would attack the nervous system.
They called this experimental allergic encephalomyelitis (EAE), and decided the same process was responsible for MS. All subsequent treatments have been based on this theory.
But the neurologists say EAE is completely different from MS.
Dr Behan said: "There are huge differences, and they've been skipped over.
"For instance, EAE either kills animals or leaves them with permanent disabilities. It doesn't come and go like MS."
Animals with EAE also suffer severe nerve inflammation, whereas in MS inflammation is usually mild, if present at all.
The neurologists believe the key to MS lies with malfunctioning astrocytes, cells that support and nourish nerve cells.
Dr Behan said there is increasing evidence that astrocytes go awry in MS patients.
"They go crazy, and multiply like mad," he said.
The damage then starts to spread, perhaps triggered by an as-yet unidentified chemical messenger.
Dr Behan speculates that releases of this factor correspond to periods of deterioration in MS patients.
They point out that MS and other diseases involving astrocytes have all been linked to regions of the same chromosome.
Mainstream researchers reject many of these arguments.
Stephen Reingold, of the National Multiple Sclerosis Society in New York, said some drugs - most notably glatiramir acetate and beta interferon - had proved successful in treating MS.
He said: "None are cures. But the immunoregulatory agents do provide relative benefits and there are dozens of publications and regulatory approvals worldwide that attest to this."
Dr Alastair Compston, of Cambridge University, said that although MS and other astrocyte diseases are linked to the same chromosome, they are linked to different regions.
Charlie Courtauld, TV critic of the Independent on Sunday, who has MS, said patients were very unsure about whether the current drugs were actually helping them.
He told the BBC: "What you are never told is that you can't really tell how they are working, because they are supposed to reduce the frequency of attacks rather than be a cure.
"They can't tell until you are dead.
"There is no single thing that is right for you, what you are trying to do is find the thing that works best among all the guess work."
A paper on the new MS theory is published next week in the Journal of
the Royal College of Physicians of Edinburgh.
© Copyright 2002, BBC