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Lecture 3

HLTC23H3 Lecture Notes - Lecture 3: Romanian Orphans, Neural Tube Defect, Feral Child

Health Studies
Course Code
Jason Ramsay

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LECTURE 3: Biological bases of human development: genes, environment, brain development
May 28, 2012
-the gradient:
-common pattern of increase or decrease in a health outcome variable related to an increase or
decrease in a measure of socioeconomic status (SES)
-we will discuss the gradient effects on:
-increasing health status
-increasing neurocognitive status
-within a social determinants of health perspective
-the idea of the “gradient” in prediction/accounting for health outcomes springs from the “social
determinants of health” perspective
-this perspective argues that risk factors operating at the population level, that are socially
distributed are as important as individual risk factors (e.g. smoking vs. % country below the
poverty line)
-public health agency of Canada: “The weight of scientific evidence supports a socioeconomic
explanation of health inequalities. The roots of ill health can be found in such determinants as income,
education and employment as well as in the material environment and lifestyle. Also of significance is
that poverty in Canada falls disproportionately on children.”
-the three big facts:
1) Differences in income distribution deeply affects health status of a country’s citizens
2) The steeper the SES or income gradient, the steeper the differences in health status between
rich and poor
3) Gradient effects are found throughout history across the globe and are persistently correlated
with developmental health status and outcome, when controlling for individual factors
-examples of SES gradient effect of reading performance:
-there is a clear relationship between mean SES (of the school the child attends) and the level of
reading ability of children attending that school
-on average, Canada is a bit better, but still shows the effect

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-what the gradient reveals:
-SES plotted against any major disease globally reveals:
-SES is a main factor
-Some US states (e.g. Louisiana) have profiles like some sub-saharan African states (e.g.
-more revealing if you look at disease vs. % GDP spent on healthcare (US sinks) relative
to poorer but more forward thinking countries)
-a flatter gradient is better for all
-the gradient and children:
-longitudinal population studies suggest that early experiences (even prenatal can have
profound effect on later health outcomes
-a good example is folic acid and neural tube defects in fetus
-SES gradient effects are entrenched by kindergarten
-by school age, this sets the child up for a pathway to further resilience or further risk
-recent studies show that the effects of the early environment can have a profound effect on
adult health outcomes
Models for the Effects of the SES Gradient on Health Outcome in Children and Adults
-how does SES gradient determine health outcome?:
-there are three main processes:
1) latent effects
2) pathway effects
3) cumulative effects
-latency model:

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-latency model: “the dye is cast” specific biological factors or developmental opportunities at
critical periods have a lifelong impact on health and well-being regardless of how life turns out
later in development
-two main pieces of evidence bear this out:
1) reports of feral children
2) research on Romanian orphans carried out by the Sir Michael Rutter group at UC
-moon-shot model of developmental deviation:
-sidebar: critical periods:
-there is evidence that humans have “critical” or sensitive periods during development in which
the biological system is maximally sensitive to environmental input
-brain inputting at genetically set intervals is affected by amount of external stimulation
-once the critical period is past, the person may still be able to “catch up” developmentally, but
it takes a significantly greater amount of energy and investment to perform a “do-over”
-critical periods:
-periods where the brain is maximally receptive to environmental input:
Language acquisition (Chomsky) Language acquisition support system (Bruner)
-when “specific high probability information from the physical or social environment is required
-Romanians orphan:
-found in the late 80s early 90s that Romanian orphans lived in terrible, neglectful and
malnourished conditions:
-very little human contact
-adopted out to British families
-Sir Michael Rutter’s group at UC London began a follow-up study
-at baseline all orphans were behind their aged matched British peers in all regards
In a few years, they had virtually “caught up” in terms of cognitive development
-social emotional development, however, was very impaired
-children had lasting impairments that had a profound effect on their psychological and
emotional development
-this impairment put them at heightened risk for many poor outcomes, including death
-biological embedding:
-the process whereby critical periods of development interact with environmental influences to
causally influence development is called “biological embedding”
-biological embedding takes place at the neuronal, neurochemical and hormonal level
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