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"Kids'
Lives Were Actually Better"
Perhaps Diamond's greatest coup to date, however, was her
work with the metabolic disorder PKU. Children with the disorder
don't metabolize protein properly. Too much of one kind of
amino acid (phenylalanine) builds up in the blood stream,
while levels of another (tyrosine) drop dangerously low. If
the disorder is not diagnosed within days of birth, a child
with PKU will sustain severe brain damage and mental retardation.
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"Little kids and babies really do see the world
differently than we do. "
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A
strict low-protein diet will prevent the brain damage. But
protein is obviously an important dietary nutrient. So how
low is low enough? Previous research had determined that children
who maintained phenylalanine levels at 10mg/dl or lower had
IQ's in the normal range, were not mentally retarded and did
not have brain damage.
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| Diamond
has used brain scans to correlate anatomy and behavior
throughout her career. |
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But,
according to Diamond, these normal IQ's and lack of mental
retardation did not mean all was well for these children.
But,
doctors couldn't understand a mechanism by which damage would
be specific to the prefrontal cortex. Diamond - somewhat serendipitously-
knew of some researchers who could understand.
"When
I was at Yale Medical School, on the floor below me was the
pharmacology department," she recalls. The researchers had
found that certain neurons that affect the prefrontal cortex
are much more sensitive to changes in the levels of tyrosine
than other neurons. "The two communities hadn't been
talking to each other. When they did, then the answer is obvious."
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"It certainly surprised me that sometimes you could
know the right answer, or know what you wanted to do and
not be able to do it."
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The
answer was that while the low-protein diet protected much
of the brain, it wasn't low enough to protect the sensitive
frontal lobes. Diamond collaborated on more research to redefine
the acceptable blood levels for children with PKU, finding
that children who kept their blood phenylalanine at 2-6 mg/dl
- levels even lower than previously recommended- have no detectable
brain damage at all.
"So,
the United States and Britain and Netherlands and Denmark
changed their guidelines," says Diamond. "Now there are lots
of other studies that have shown that the kids who stay on
that diet never show the problems. In fact, kids who go [on
the stricter diet] show a reversal of their problems." 
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