Monday January 21 11:55 PM EST
MONDAY, Jan. 21 (HealthScoutNews)
-- 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.
Copyright © 2000 Healthscout.com
By Nicolle Charbonneau
HealthScoutNews Reporter