Full Text: http://www.cma.ca/jpn/vol-24/issue-2/0103.htm)
Because we believe that autism is closely related to hypothyroidism,
we have
conducted a brief literature search to compare some factors associated
with
both autism and hypothyroidism. We have chosen a recent review by
Trottier
et al entitled "Etiology of infantile autism: a review of recent
advances in
genetic and neurobiological research", published recently in the
Journal of
Psychiatry and Neuroscience to compare some of the findings.
BACKGROUND:THYROID HORMONES & BRAIN

Thyroid hormones are closely related to all brain function. This
common
knowledge serves as the basis for the world wide iodine supplemention
program. Healthy humans require iodine, an essential component of the
thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Failure to
have
adequate iodine leads to insufficient production of these hormones
(hypothyroidism), which affect many different parts of the body,
particularly muscle, heart, liver, kidney, and the brain. The most
devastating of these consequences are on the developing human brain.
(Venkatesh-Mannar & Dunn, 1995)

Iodine deficiency has been called the world's major cause of
preventable
mental retardation. The damage to the developing brain results in
individuals poorly equipped to fight disease, learn, work effectively,
or
reproduce satisfactorily.

Thyroid hormone levels are so delicate that even subclinical
hypothyroidism
in a pregnant women (meaning no clinical signs are observable) may
result in
loss of IQ in the newborn (Haddow, 1999). Currently in the US this
includes
officially over 2.5 % of mothers to be. 1988 to 1994 was a period in
which
15 percent of women of childbearing age had concentrations lower than
50 =B5=
g
per liter, the level of intake at which thyroid secretion clearly
becomes
overtly inadequate.  (Utiger, 1999)

Because of the difficulties in testing for and diagnosing
hypothyroidism,
the actual numbers are presumed to be much higher. Haddow's study
reports
that pregnant women with underactive thyroids are four times more
likely to
have children with low IQs if the disorder is left untreated. The
study
found that 19 percent of the children born to mothers with thyroid
deficiency had IQ scores of 85 or lower, compared with only 5 percent
of
those born to mothers without such problems. The children who score in
this
range may face lifelong developmental challenges. In a accompanying
press
release Haddow said, "It's the kind of cutoff that tells you you're
going to
have more troubles in school and more troubles in life in general."

TOLL OF IODINE DEFICIENCY: http://www.idrc.ca/mi/idddocs/iodman1.htm

1.570 billion people (or 29% of the world's population) are affected.
Brain
Damage: 26 Million
Goiter:655 Million
Cretinism: 5.7 Million
Deaths related to IDD: at least one child a minute