Cognitive performance childhood

In this book I use the term fetal programming —without reference to mechanism—to describe environmental impact of any kind on the fetus that produces alterations in health and disease apparent at any time in childhood or adulthood. This idea is essentially an extension into the prenatal period of more general conclusions about the role of early experience in later life. Included in this conception are postnatal temperament, behavior patterns, intelligence, psychopathology, and so on—the behavioral focus of this book. The point is that sometimes postnatal consequences of prenatal environmental impacts involve more than just alterations in the physiology of organ systems—such impacts can also have consequences for later behavior and cognitive performance. 

Researchers argue about the effects of prenatal exposure to PCBs on brain development and later childhood cognitive performance. Some studies find effects and some don t. Some studies do not involve direct measurements of PCBs in blood but rely on surrogate (proxy) measurements, such as consumption of fish from contaminated waters. It s also difficult to locate a population in which fetuses have been exposed to PCBs but not to other toxins. It may be that cognitive effects are limited to certain kinds of brain-work not revealed by current tests. We don t know yet. But given all the evidence that exists about serious effects in animals and human adults, and given the general axiom that the human fetus is about a hundred times more vulnerable than adults to toxins, it s reasonable to say that the question of the effects of prenatal exposure to PCBs is not yet resolved. 

This chapter is about the effects of the prenatal environment on childhood and adult intelligence quotient (IQ), but it needs to be more than that, since once the prenatal environment is admitted as an important determinant of postnatal behavior and cognitive performance, some old hereditarian ideas must be abandoned. Abandonment of these old ideas will be a critical step forward in the twenty-first century, and I want to outline here the reasons for the shift among researchers. The problem for the general reader is that although the new view of IQ involves concepts in statistics and psychometrics, I have committed myself to tell the story without graphs or equations. I do hope this works for the general reader, but if in a few places the discussion seems too technical, I advise the reader... 

Cognitive performance is brain performance. In general, any prenatal impact that affects the fetal developing brain has the potential to affect childhood and adult cognitive performance. There is no biological reason why this should not be so. 

Neurodevelopmental and cognitive outcomes among prenatally cocaine exposed children have been documented by measuring school performance in 62 cocaine-exposed and 73 control children who were students at an American inner-city school (328). The children were followed prospectively from birth to the end of the 4th grade. Their report cards, standardized test results, teacher and parent reports, and birth and early childhood data were... 

Mendez MA, Adair LS. Severity and timing of stunting in the first two years of life affect performance on cognitive tests in late childhood. JNutr 1999 129 1555-1562. 

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