Neurodevelopment and IQ

Neurodevelopment refers to the growth of the nervous system, especially the brain. The term refers to the healthy establishment of brain structures that in turn support our movement and thinking abilities (like our reflexes, coordination and intelligence). The process of neurodevelopment can be disrupted by chemical changes inside the body, through environmental exposures, or other factors.

What is Neurodevelopment?

  • The main periods when neurodevelopment occurs are while in the womb, during infancy, and in adolescence.
  • Neurodevelopment includes the development of our abilities to think and move. Disorders of neurodevelopment include mental retardation, autism, and other mental and physical disabilities.
  • Changes in the environment inside or immediately surrounding the body of the fetus, infant or adolescent can change the course of their neurodevelopment and have lifelong negative impacts.
  • Messenger chemicals in the body, thyroid hormones, in particular, play an important role in supporting healthy neurodevelopment, and disruption of these hormones can have serious health effects.

What is IQ, or Intelligence Quotient?

  • “Intelligence Quotient” is a term used to discuss someone’s performance on tests of thinking skills.
  • IQ can be impacted by problems with neurodevelopment, so evaluating IQ can suggest the possible presence of neurodevelopmental problems.
  • It is important to note that IQ tests evaluate “general intelligence” but are a measure of certain kinds of thinking abilities only, so IQ may not be indicative of a person’s full range of cognitive abilities. In spite of its shortcomings, IQ testing is a useful data gathering tool.

For more information about IQ testing:

CERCH Findings on Neurodevelopment and IQ:

From the CHAMACOS Study: Health Outcomes Study - 

Organophosphate (OP) pesticides:

  • Mothers’ exposure to organophosphate (OP) pesticides during pregnancy is associated with:
    • Lower IQ and poorer cognitive functioning in children. (Go to publication 1, 2)

Organochlorine (OC) compounds:

  • Higher levels of DDT in mother’s blood during pregnancy were associated with:
  • Prenatal exposure to PCBs (organochlorine compounds) is associated with:
    • Altered thyroid hormone levels in mothers. (Go to publication)
    • For certain PCBs, prenatal exposure was associated with neonatal thyroid hormone levels. (Go to publication)

Flame Retardants:

  • Higher PBDE exposures during pregnancy were associated with:
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