MS 'may be four different diseases'

Multiple sclerosis is a complex disease

The crippling degenerative disorder multiple sclerosis may actually be four different diseases, say researchers.

An international team of scientists carried out tests on more than 80 MS patients.

They found that although the patients had similar symptoms they were the result of four different causes.

Lead researcher Dr Hans Lassmann, from the University of Vienna, said the team had still to identify exactly what the causes were.

Therapies must be tailored towards the needs of specific patient subgroups

Dr Hans Lassmann, University of Vienna

They speculate they may include viruses or disorders of the immune system.

Dr Lassmann said the research indicated that treatments that might aid one patient could potentially be harmful to another.

He said: "Therapies must be tailored towards the needs of specific patient subgroups."

Multiple sclerosis is caused when myelin, the fatty substance that protects the nerves, is damaged or destroyed and replaced with scar tissue.

This scarring, called sclerosis, slows the electrical signals in the nerves.

Depending on which nerve fibres are affected, patients have symptoms ranging from weakness and clumsiness to numbness, visual disturbances, and even emotional and intellectual changes.

Some patients experience cycles of relapse and remission while others have a steady progression to severe debilitation and death.

Tissue samples

Dr Lassmann and collaborators from the Mayo Clinic in Rochester, Minnesota and the University of Gottingen in Germany gathered tissue samples from 51 patients who had brain biopsies performed during acute flare-ups of MS and 32 who died during acute episodes.

The researchers were able to identity four distinctly different patterns of nerve demyelination among the patients.

This, they believe, indicates profound differences in the way the disease was caused.

Some researchers believe that MS may be caused by a virus.

A virus resembling polio easily causes MS in laboratory mice.

But the condition also resembles an autoimmune disease, in which the immune system mistakenly attacks healthy tissue.

Dr Lassmann's research suggests both theories may be correct.

A spokesman for the UK MS Society said: "It is known that there are different types of MS and that there could be variations in the cause of the disease.

"This latest research is welcome in helping to increase our understanding of MS and potentially more effective ways of treating it.

"Until then we must continue to rely on clinical judgement based on properly conducted trials to decide which disease-modifying therapies and symptomatic treatments are appropriate in individual cases."

Dr Lorna Layward, head of research at the society, said clinical trials had shown that some patients responded to current drugs in use such as beta interferon and copaxone, while others did not.

She said it appeared that these drugs were more effective for patients suffering from acute attacks of multiple sclerosis, rather than those whose condition was growing gradually worse.

The research is published in the Annals of Neurology.