low-level thyroid->intelligence mechanisms

[ttweed@wildrockies.org (Tony Tweedale)]

 in some meandering medical research I came across:

Haddow et al 'Maternal Thyroid Deficiency...and Subsequent
Neuropsychological Development in te Child' _NEJM_ 341:8:549-555 (19 Aug
'99)

found that the ~2% of U.S> pregnant women w/ mild (undiagnosed)
hypothyroidism (t. deficiency) may be causing a 4 point IQ drop, and those
with greater (diagnosed) hypoth. had a greater IQ drop.  Other work found
impaired psychomotor development at the 12th week of gestation whose mom's
had lower serum free (unbound) thyroxine (is that T3 or T4--I forget?).
Fetal thyroid gland isn't active until ~12th week   Later brain
development--heavier in migration and organization of cells--affects the
impaired higher (than psychomotor) functions measured in their study, the
authors say.  They emphasize the effects appearance long after birth, and
thus the need for hypoth. screening during or before pregnancy.

As you know, both planar (Ah receptor mediated) and non-planar PCBs are
heavily implicated in causing cognitive and other neurologic effects (in
lab and in epidem.), and some are known to interact w/ thyroid hormone
systems.

Tony Tweedale

Causality is a concept not subject to empirical demonstration. -David Hume
(1711-'76)

Temperate but endangered planet.  Enjoys weather, northern lights,
continental drift.  Seeks caring relationship with intelligent life form.
      -Friends of the Earth