Intelligence quotient significantly influences important life outcomes

Evidence

For just a few dollars a ton, adding iodine to salt (in the form of potassium iodide) greatly lowered the incidence of deficiency and goiters. But during World War II, when a new crop of Air Force recruits was tested with the Army General Classification Test, scientists noticed a pattern: men from low-iodine areas who showed improved thyroid health also scored substantially higher on the intelligence test. It turns out that iodine deficiency is an unrecognized cause of mental retardation, especially, but not exclusively, in unborn children. — Harriet A. Washington, A Terrible Thing to Waste, 21 (#exemplifies, via linked claim)

Categorization

• corroborated: 3 independent passages support this claim
• XREF: connects to: Toxocara canis infection lowers IQ independent of socioeconomic and racial factors — Harriet A. Washington, A Terrible Thing to Waste, 980; National infectious disease burden strongly predicts average national IQ — Harriet A. Washington, A Terrible Thing to Waste, 937; Iodine deficiency is a major unrecognized cause of lowered intelligence — Harriet A. Washington, A Terrible Thing to Waste, 21 (+5 more)

Related

• Iodine deficiency is a major unrecognized cause of lowered intelligence (similarity 0.91)
• Toxocara canis infection lowers IQ independent of socioeconomic and racial factors (similarity 0.89)
• A small average IQ drop hugely swells rates of disability and shrinks giftedness (similarity 0.87)
• National infectious disease burden strongly predicts average national IQ (similarity 0.85)
• Rapid IQ gains from reduced disease burden rule out genetic explanations (similarity 0.84)
• Iodine deficiency is the leading global cause of mental retardation (similarity 0.84)
• Adding iodine to salt in 1924 raised average U.S. IQ scores (similarity 0.82)
• Eugenic ideology suppressed research into infectious causes of low IQ (similarity 0.82)
• Intelligence develops from environment and experience rather than genetic inheritance (similarity 0.81)
• Iodine deficiency impairs brain development in children even without obvious physical effects like goiter, and even relatively low fetal deficiency can significantly reduce IQ. (similarity 0.81)
• IQ test results strongly predict income, education, health, and longevity, though weaker for individuals (similarity 0.81)
• Policies and interventions can raise a nation’s average IQ (similarity 0.81)
• A randomized trial in Ethiopia found iodized salt raised children’s cognitive scores by only about 4 IQ points (effect size d=0.17), far below a full standard deviation. (similarity 0.80)
• A 2017 study found that the introduction of iodized salt in 1924 raised IQ for the one-quarter of the population most deficient in iodine. (similarity 0.80)
• Iodine played a substantial role in cognitive improvements across the American population in the 20th century. (similarity 0.80)

Broader Connections

• Iodine deficiency is a major unrecognized cause of lowered intelligence #exemplifies (0.74) — Harriet A. Washington, A Terrible Thing to Waste, 21
• National infectious disease burden strongly predicts average national IQ #exemplifies (0.72) — Harriet A. Washington, A Terrible Thing to Waste, 937
• Toxocara canis infection lowers IQ independent of socioeconomic and racial factors #exemplifies (0.70) — Harriet A. Washington, A Terrible Thing to Waste, 980