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Autism May Be Linked to
Immune Reactions
By Jeanie Davis WebMD
Medical News, Reviewed By Brunilda Nazario, MD.
http://my.webmd.com/content/article/3606.2234
For more articles on disabilities and special ed visit
www.bridges4kids.org.
It's something many parents know: If a child is autistic,
keeping milk and wheat out of the
diet helps tame symptoms. But now, scientists think
they understand why.
A new study seems to unlock an important piece
the puzzle, indicating a link with
the immune system.
Autism is a complex syndrome that appears in early childhood;
autistic children have difficulties
in language development, social
interactions, and repetitive
patterns of behavior -- such as banging their head against
the wall. Whereas a genetic
predisposition puts children at high risk of
developing autism, scientists have
long debated the other triggers that
cause the disorder.
Recent studies have shown that children who
drink less (or no) milk -- and eat
fewer (or no) wheat products -- have
improvement in symptoms. They have
better social contact, less self-harm (such as head banging),
and fewer "dreamy state"
periods. Other studies have pointed to environmental
toxins -- specifically bacterial
and viral infections -- as triggers, says
Aristo Vojdani, assistant research professor in
neurobiology at UCLA and
director of Immunosciences Lab Inc. in Beverly Hills,
Calif. "My study puts the pieces
together, how infection produces
autism symptoms," he tells WebMD.
His study appears in the August issue of the
Journal of Neuroimmunology.
In his study, Vojdani tested the
blood of 80 children -- 40 who were
autistic and 40 who were not. He looked for any of 12
different antigens --
signs of an immune reaction to various proteins of the
brain and nervous system.
Autistic children showed
signs of an immune reaction to milk protein
and two common infections -- streptococcus and
Chlamydia pneumoniae.
Antibodies to milk proteins and antibodies from viruses
can be damaging -- and could cause
breakdown in what's called the blood-brain
barrier.
The blood-brain barrier is similar to a
membrane, one that protects our
brains from infectious viruses and
bacteria. However, various
environmental toxins -- such as mercury, lead, and metals --
can cause antibodies to cross the
blood-brain barrier, combine with other brain tissue
antigens, and thus damage brain
tissue. The researchers also
note that although these autistic children had
higher levels of these antibodies in
their system, they did not look at
whether these antibodies represent a risk factor for
autism. Studies
conducted two years ago showed that when milk protein
is injected into mice, they
developed multiple sclerosis-like
symptoms, says Vojdani. The same
thing happened when streptococcus and C. pneumoniae
protein were injected into mice.
Vojdani's study contains "interesting findings,
but they need to be replicated,"
says Fred Volkmar, MD, a child
development specialist at Yale
University, and the director of the newly established Autism
Research Center at Yale.
His advice to parents: "Don't change a thing [in your
child's diet] until we report more
evidence." "I
think there is substantial validity to the idea that
autoimmunity is lined to autism,"
says Bradley Pearce, MD, assistant
professor of psychiatry at Emory
University School of Medicine in Atlanta.
"There's a substantial
genetic component to autism and to
autoimmunity, in that patients with autism have a higher rate
of having someone in their family
with another autoimmune disease. So the idea is I
think pretty solid. The
problem is cause and effect. When
we're looking at these antibodies,
whether they're actually causing any of the
symptoms, we don't really
know that. This paper was reasonably well done, but when it
comes to cause and
effect, it doesn't prove it."
Another possible cause of autism: "It could
also be that the antibodies they
found in this paper are really the
result of the disease rather than
the cause. They may be present because there is something
wrong with
blood-brain barrier."
Also, there may be a genetic abnormality in
autism that affects both the brain
and the immune system, says Pearce.
"There may be some common molecule
involved in the brain and in the immune function, but that
doesn't mean the immune
abnormality is causing brain abnormalities.
"It's also possible that the cause of
autism starts primarily with an
abnormality in the immune system, that for some reason
the immune system is
hyperactive and these antibodies produce molecules that
cross-react with brain molecules and
cause the disease," he says.
However, there's a glitch in Vojdani's logic,
says Pearce. "Changes in the brain
that cause autism are not similar to
changes that cause MS. Autism is not
associated with changes in myelin -- the white matter of the
brain -- like MS is. In
families where there is autism, there is increased incidence
in autoimmune disease, but
they don't always affect the myelin."
Also, the characteristics of autism and the course of
the disease development are not like
a typical autoimmune disease, he says.
However, the idea of autoimmunity and
autism "is an interesting idea,
it's plausible," says Pearce. "The idea that an
antibody can cause a complex
psychological disease -- like schizophrenia -- is fairly well
established. There are a lot of
pieces of puzzle that haven't quit
fit together yet, however."
Should kids with autism stop drinking milk?
"Many parents choose not to give
them milk just because autistic kids
have a lot of gastrointestinal
problems," says Pearce. "Whether it actually modulates
disease, I really doubt. Actually,
the GI problems may be associated with the disease."
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