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Brain Differences Detected in Relatives of MS Patients

This may leave them at higher risk of developing the disease, study says

MONDAY, Jan. 21, 2002 (HealthDayNews) -- A new brain imaging study suggests that relatives of people with multiple sclerosis may be at higher risk of developing the disease.

Using a relatively new method of scanning brain tissue, researchers in Poland and Italy have discovered that closely related family members have slightly smaller amounts of a certain type of brain tissue. This is true even when the relatives have no neurological symptoms of multiple sclerosis, the researchers say.

The difference in brain tissue, which is not visible on conventional magnetic resonance imaging (MRI), is the first evidence that there are variations in the brain tissue of people with MS. The findings appear in the Jan. 22 issue of the journal Neurology.

In patients with multiple sclerosis (MS), their own immune system mistakenly attacks myelin, a protective insulation surrounding cells found in the brain, nerve fibers and spinal cord. The progressive loss of myelin leads to muscle weakness and, often, paralysis.

More than 350,000 Americans have MS. While drug therapies can reduce symptoms in some patients, there is no known cure.

In some families, more than one person develops multiple sclerosis, suggesting that some kind of genetic link is involved.

Dr. Krzysztof Selmaj and his colleagues at the Medical University of Lodz in Lodz, Poland, working with a researcher at the University Ospedale San Raffaele in Milan, decided to look at some of these families in greater detail. They used imaging techniques to help examine the brains of 30 relatives of MS patients.

Before the imaging, all the relatives underwent neurological examinations and had no MS-related symptoms.

The researchers used magnetization transfer imaging (MTI), a relatively new offshoot of conventional MRI, to examine the 30 relatives. Half of those studied were from families with a history of MS; the other half came from families where the disease appeared to have no genetic link – so-called sporadic MS.

The relatives' MTI scans were then compared to those of 15 healthy volunteers, 15 people with familial MS and 15 people with sporadic MS.

"[MTI] measures the integrity of micromolecules in the brain," says Selmaj. "One of the major micromolecules in the brain is myelin."

Selmaj found a reduction of brain tissue known as white matter in relatives of the MS patients who had familial and sporadic MS. White matter, which normally makes up about 60 percent of the brain's volume, consists primarily of nerve fibers and supporting cells.

The researchers found that the relatives' average volume of white matter was closer to that of the people with MS than to that of control-group members without the disease.

"But these [differences] are quite subtle," says Selmaj. In addition, "the myelin seems to be slightly affected – either the composition or the structure is slightly changed," he adds.

It's possible that the subtle, though widespread, changes seen in the white matter of the relatives could be precursors to the more concentrated myelin damage found in MS patients, Selmaj says.

This could make the relatives "predisposed to getting MS at a higher frequency than the general population," he says.

But he stresses that the findings aren't definitive and shouldn't frighten relatives of people with MS.

"There is some genetic component to MS. We can't escape it and they should be aware of it," Selmaj says. But, he adds, "it's not 100 percent proven that these changes will [become] lesions and become MS."

Selmaj says it's too early to suggest drug therapies for relatives of people with MS.

If it's eventually proven that relatives with the most significant differences in white matter go on to develop MS, it might be possible to one day prescribe drugs that would slow the disease's progression.

Sridar Narayanan, a researcher at McGill University's McConnell Brain Imaging Centre in Montreal, says MTI technology is far better at detecting the kinds of subtle changes discussed in these findings.

"Relatives of patients with MS share genetic material and they may have some abnormality of their myelin that's genetically transmitted and pre-existing," says Narayanan. "If they're presented with the appropriate environmental trigger, which is a whole other area of research … people with the appropriate genetic makeup have structurally different myelin which is more susceptible to damage."

The researchers scanned the relatives about 18 months ago. Selmaj says they intend to follow up with more brain scans on a regular basis to see whether the relatives develop early signs of the lesions that cause MS.

Selmaj also plans to use an imaging technique called MRI spectroscopy to examine the relatives, to see whether there is evidence of biochemical changes in their brain tissue.

What to Do: For more information on multiple sclerosis, check out the Web sites of the National Multiple Sclerosis Society, the Multiple Sclerosis Association of America, or the Multiple Sclerosis Foundation.

SOURCES: Interviews with Krzysztof Selmaj, M.D., Ph.D., professor, chairman, department of neurology, Medical University of Lodz, Lodz, Poland; Sridar Narayanan, M.Sc., McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada; Jan. 22, 2002, Neurology
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