- GAINESVILLE, Fla.---Findings from two novel animal studies indicate autism
and schizophrenia may be linked to an individual's inability to properly
break down a protein found in milk, University of Florida researchers report
in this month's issue of the journal Autism.
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- The digestive problem might actually
lead to the disorders' symptoms, whose basis has long been debated, said
UF physiologist Dr. J. Robert Cade, cautioning that further research must
take place before scientists have a definitive answer. When not broken
down, the milk protein produces exorphins, morphine-like compounds that
are then taken up by areas of the brain known to be involved in autism
and schizophrenia, where they cause cells to dysfunction.
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- The animal findings suggest an intestinal
flaw, such as a malfunctioning enzyme, is to blame, says Cade, whose team
also is putting the theory to the test in humans. Preliminary findings
from that study - which showed 95 percent of 81 autistic and schizophrenic
children studied had 100 times the normal levels of the milk protein in
their blood and urine - have been presented at two international meetings
in the past year but have not yet been published.
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- When these children were put on a milk-free
diet, at least eight out of 10 no longer had symptoms of autism or schizophrenia,
says Cade, a professor of medicine and physiology at UF's College of Medicine
and inventor of the Gatorade sports drink. His research team includes research
scientist Dr. Zhongjie Sun and research associate R. Malcolm Privette.
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- "We now have proof positive that
these proteins are getting into the blood and proof positive they're getting
into areas of the brain involved with the symptoms of autism and schizophrenia,"
Cade said.
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- More than 500,000 Americans have some
form of autism, according to the Autism Society of America. The developmental
disability typically appears during the first three years of life and is
characterized by problems interacting and communicating with others. Many
individuals exhibit repeated body movements such as hand-flapping or rocking
and may resist changes in routine. In some cases, they may display aggressive
or self-injurious behavior.
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- Schizophrenia is noted for disturbances
in thinking, emotional reaction and behavior and is the most common form
of psychotic illness. More than 2 million Americans suffer from it, according
to the National Institute of Mental Health. People with schizophrenia often
hear internal voices not heard by others, or believe others are reading
their minds, controlling their thoughts or plotting to harm them. In addition,
their speech and behavior can be so disorganized that they may be incomprehensible
or frightening to others.
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- In the UF studies, researchers injected
rats with the protein beta- casomorphin-7, one of the key constituents
of milk and the part that coagulates to make cheese. They then observed
their behavior and later examined brain tissue to see whether the substances
accumulated there.
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- Beta-casomorphin-7 was taken up by 32
different areas of the brain, Cade said, including sections responsible
for vision, hearing and communication.
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- "This could explain several of the
things one sees in autism and schizophrenia, such as hallucinations,"
he said. "If part of the brain puts out a false signal because of
casomorphin, it could result in the person seeing something that's not
really there; either a visual or auditory hallucination could occur.
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- "There are a whole number of behaviors
that the rat has after beta-casomorphin-7 that are basically the same as
one sees in the human with autism or schizophrenia," he added. "If
we ring a bell beside a rat's cage, it normally looks up to see where the
noise is coming from. But the rats after beta-casomorphin-7 didn't do that
- they were completely oblivious to the bell-ringing above them. This struck
us as interesting because many mothers of autistic children comment that
they seem at times to be totally deaf -- they talk to their children and
they just don't seem to hear them."
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- Researchers suspect the process begins
in the intestine, where the body absorbs the protein when a person eats
foods containing it.
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- "We think this process is linked
to the production of antibodies in the gut when you eat something you're
sensitive to," Cade said. "Both schizophrenics and autistics
have a high incidence of [certain] antibodies, and a high incidence of
diarrhea, which points to an intestinal disorder. So we think that with
autism and schizophrenia, the basic disorder is in the intestine, and these
individuals are absorbing beta-casomorphin-7 that they normally should
break down in the body as amino acids, rather than peptide chains up to
12 amino acids long."
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