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March 22, 2007-Forwarded by Elise Miller- CHE-LDDI
Autism: It's Not Just in the Head
The devastating derangements of autism also show up in the gut
and in the
immune system. That unexpected discovery is sparking new
treatments that
target the body in addition to the brain.
by Jill Neimark, Discover
http://discovermagazine.com/2007/apr/autism-it2019s-not-just-in-the-head
Article Summary:
Autism, traditionally seen as genetic and originating in the
brain, is
starting to be viewed in a broader and very different light, as
a possible
immune and neuroinflammatory disorder. As a result, autism is
beginning to
look like a condition that can, in some and perhaps many cases,
be
successfully treated. A disparate group -- immunologists,
naturopaths,
neuroscientists, and toxicologists -- is turning up clues that
are yielding
novel strategies to help autistic patients.
New studies are examining contributing factors ranging from
vaccine
reactions to atypical growth in the placenta, abnormal tissue in
the gut,
inflamed tissue in the brain, food allergies and disturbed brain
wave
synchrony. Some clinicians are using genetic test results to
recommend
unconventional nutritional therapies, and others employ drugs to
fight
viruses and quell inflammation.
Above all, there is a new emphasis on the interaction between
vulnerable
genes and environmental triggers, along with a growing sense
that low-dose,
multiple toxic and infectious exposures may be a major
contributing factor
to autism and its related disorders. One can distill a few
revolutionary
insights from among the many potential avenues of research.
First, autism
may not be rigidly determined but instead may be related to
common gene
variants, called polymorphisms, that may be derailed by
environmental
triggers. Second, affected genes may disturb fundamental
pathways in the
body and lead to chronic inflammation across the brain, immune
system, and
digestive system. Third, inflammation is treatable.
Harvard pediatric neurologist Martha Herbert has authored a
14,000-word
paper in the journal Clinical Neuropsychiatry that
reconceptualizes the
universe of autism, pulling the brain down from its privileged
perch as an
organ isolated from the rest of the body. "What I believe is
happening is
that genes and environment interact, either in a fetus or young
child,
changing cellular function all over the body, which then affects
tissue and
metabolism in many vulnerable organs. And it's the interaction
of this
collection of troubles that leads to altered sensory processing
and impaired
coordination in the brain. A brain with these kinds of problems
produces the
abnormal behaviors that we call autism."
Each child's path to autism may be distinct, she says, but they
may share
common inflammatory abnormalities. She has shown through
morphometric brain
imaging that white matter -- which carries impulses between
neurons -- is
larger in children with autism. If white matter is chronically
inflamed,
then one potential treatment approach is to down-regulate the
brain's immune
response.
Jill James, director of the Autism Metabolic Genomics Laboratory
at the
Arkansas Children's Hospital Research Institute (and professor
of pediatrics
at the University of Arkansas for Medical Sciences) has found
that many
children with autism do not make as much of a compound called
glutathione as
neurotypical children do. Glutathione is the cell's most
abundant
antioxidant, and it is crucial for removing toxins. If cells
lack sufficient
antioxidants, they experience oxidative stress, which is often
found with
chronic inflammation. Oxidative stress in some autistic children
may be
treatable with targeted nutritional intervention.
Genetic vulnerability -- related to immune system, brain, and
gut -- must
also be considered. Pat Levitt, director of the Vanderbilt
Kennedy Center
for Research on Human Development, and his colleagues recently
discovered
that a common variant of a gene called MET doubles the risk of
autism. The
finding was widely regarded as a breakthrough because MET
modulates the
nervous system, gut, and immune system -- just the kind of
finding that
matches up with the emerging new view of autism.
The gene variant occurs in 47 percent of the population -- in
other words,
it is just one contributing factor, and it probably works in
concert with
other vulnerability genes. The activity of the gene is affected
by what is
known as oxidative stress -- the kind of damage one sees with
excessive
exposure to toxins. Several large-scale, federally funded
epidemiological
studies are under way to pinpoint possible environmental
triggers, as well
as early biomarkers of autism. The trick is to build a large
enough study to
be able to look at both genes and environment together. An
ambitious study,
called the Autism Birth Cohort, by Columbia University and the
Norwegian
Institute of Public Health will follow 100,000 pregnant women
for 72 months,
studying their health and genetics and testing everything from
blood to
urine samples.
The hope is to discover environmental factors that contribute to
autism
risk, from diet or infection to toxins like heavy metals,
pesticides, and
the countless synthetic molecules in products today. Other large
NIH- and
EPA-funded studies are teasing out immune abnormalities that may
contribute
to autism.
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