- Most often
strikes young adults between 20 and 40 years of age.
- Afflicts approximately
250,000 Americans.
- Forces 4 out
of 10 people with MS to leave the work force.
PROGRESS
IN MEDICAL RESEARCH
Multiple sclerosis
is a disease that results from loss of myelin (the insulation
surrounding the nerve fibers) in areas throughout the brain
and spinal cord. When myelin is destroyed, nerve conduction
is disrupted causing multiple areas of damage and resulting
in a variety of symptoms. This destruction of myelin appears
to be due to an abnormal immune response in which the body's
immune system reacts against its own tissue. The disease has
many similarities to other autoimmune diseases such as lupus
erythematosus. The cause of MS remains unknown. For a long
period of time, physicians thought that a virus was the causative
factor, but currently there is no good evidence for this.
Although MS is not genetically inherited or transmitted, there
appears to be a genetic susceptibility to the disease.
Multiple sclerosis
is difficult to detect in many cases, often taking months
or years of observation to confirm. The diagnosis requires
a history of multiple (at least two) attacks over time, often
with remission between attacks, and evidence of nervous system
involvement based upon clinical neurological examination.
The development of magnetic resonance imaging (MRI) scanning
has assisted the diagnosis, but the disease can exist with
a normal appearing MRI. Other helpful confirmatory tests include
changes in the cerebrospinal fluid and abnormal evoked potential
responses.
How
has animal research helped people with MS?
Due to the commitment
of researchers to find the cause of MS and methods of treatment
and prevention, knowl-edge about MS over the past 30 years
has expanded at a greater rate than during the entire 100
years following the initial description of diagnosis. This
is in part due to animal research. A number of treatment programs
have been proposed for people with MS which could only have
been developed from studies using animals. These include treatments
using immunosuppressive drugs and other specific agents. Animals
have been used to study how the body's immune system can be
made allergic to brain tissue. These studies have taught us
which brain substances most easily stimulate the immune system,
which genetic factors influence susceptibility to allergic
brain disease, and how other factors, such as general health,
influence the course of the disease. Is animal research on
MS still needed?
Animal research
must continue to find new and more effective treatments. In
the last few years new forms of therapy tested in animals
have quickly found their way into the clinical setting to
help MS patients. An example is the use of beta interferon,
a substance that has been shown to be effective in reducing
the number of exacerbations (episodes of worsening) of patients
with relapsing-remitting multiple sclerosis. Several other
compounds are currently being tested in animals prior to their
use in humans with MS. Animal research is also continuing
on a specific animal disease called Experimental Allergic
Encephalomyelitis (EAE), which has symptoms similar to MS.
This disease can be induced in animals using a part of myelin
isolated from central nervous system (CNS) tissue. EAE in
animals causes damage to the nervous system and, under certain
experimental conditions, a return of MS-like symptoms after
convalescence has begun. Studies of the mechanism responsible
for this disorder in laboratory animals may provide important
clues to the cause, and possible treatment of MS for humans.
What's
ahead for people with MS?
Research on multiple
sclerosis has entered a new and promising phase. Treatments
that modify the immune system are showing promise in their
ability to affect the course of the disease. The use of animals
in this research remains vital and will be essential for the
development of safe and effective vaccines. Eventually it
is hoped that a medication can be developed that will completely
protect susceptible people from attacks of MS.
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