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New research links pesticides to ADHD, other ills
Salk Institute researchers say a single gene variant could predispose
many people to develop a range of neurological disorders, ranging from
attention deficit hyperactivity disorder (ADHD) to Gulf War syndrome,
following exposure to certain pesticides. The researchers say their
findings could explain anecdotal evidence of a link between pesticide
exposure and neurological dysfunction.
Carrolee Barlow, Christopher Winrow and colleagues found that in
mice, exposure to organophosphates (a group of chemicals that include
nerve gas and certain pesticides) inhibits the activity of a gene called
neuropathy target esterase, or NTE. Mice bred to lack the NTE gene died
before birth, but those with only one copy of the gene exhibited marked
ADHD-like behavior when exposed to organophosphates. Mice with two
functional NTE genes also exhibited behavior similar to ADHD after
organophosphate pesticide exposure, but their symptoms were far milder.
The researchers note that the mice with only one copy of the NTE
gene had a 40 percent decrease in the enzyme produced by the gene,
which is active in areas of the brain controlling movement (including the
hippocampus, cerebellum, and spinal cord).
Barlow says, "NTE is a large gene. It's possible that we all have
slightly different forms of the NTE enzyme, which may explain why
some may get ADHD when they're exposed at young ages, and why
some may get Gulf War syndrome at a later age, or why some of us have
no symptoms at all. It appears to be a case of delayed toxicity, inhibiting
the function of NTE."
The findings of Barlow and Winnow follow earlier research by
Elizabeth Guillette and colleagues
(see related article, Crime Times, 1998, Vol. 4, No. 3, Page 1)
linking pesticide exposure to neurodevelopmental problems.
Guillette et al. compared Yaqui Indian children exposed to high or low
levels of agricultural pesticides, and found that the children with higher
pesticide exposure showed learning disabilities, behavior problems,
impaired memory, motor problems, and other signs of significant brain
dysfunction.
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"Loss of neuropathy target esterase in mice links organophosphate
exposure to hyperactivity," Christopher J. Winrow, Matthew L.
Hemming, Duane M. Allen, Gary B. Quistad, John E. Casida, and
Carrolee Barlow, Nature Genetics, advance online publication,
March 17, 2003. Address: Carrolee Barlow,
carrolee_barlow@merck.com.
-- and --
"Genetic link may tie together pesticides, ADHD, Gulf War syndrome
and other disorders," press release, Salk Institute, March 17, 2003.
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