Question: How can you tell how much the brain's development has been affected by the child's home life, e.g. diet, sleep, attention from parents, etc?

Michael Thomas answered on 14 Apr 2015:

Most simply, we measure things about the child’s environment, and see if they correlate with things we can measure about the brain, such as its structure or its activity levels.

Here are a couple of recent findings:

Noble and colleagues published a paper in Nature Neuroscience last week suggesting that differences in socio-economic status (SES) correlated with differences in the cortical surface area of certain brain regions. They carried out their study in the USA on around 1100 typically developing individuals between 3 and 20 years of age. Differences in SES could explain up to 4% of the variation in cortical surface area in some brain regions. Notably, the correlations seemed to be in line with the relationship between SES and cognitive abilities in these children.

In 2013, Whittle and colleagues published a paper looking at the effects of ‘positive parenting’ on the development of adolescent brain structure in Australia. They examined 188 11-13 year olds, and tested how parenting differences affected the size of parts of the brain involved in reward-based decision-making 4 years later. Only some of the regions they examined showed effects, and these depended on gender.

These are examples of some of the new knowledge base that is being assembled by researchers about environmental effects on brain development.

It is worth bearing a couple of things in mind, though. First, even though we’re finding these correlations, the important thing is their impact on behaviour. Brains can vary a lot in the sizes of different structures and still produce similar looking behaviour.

Second, studies of twins suggest about half the differences between children in things like intelligence, academic ability, and dimensions of personality, come from the environment (the rest from genetic differences). But researchers have not found it easy to pin down exactly what these environmental causes are. Most of them appear unique to the individual child. That is, influences of the environment appear to make people different rather than similar.

Third, the research is tricky, here, because in real life (rather than controlled experiments), a lot of the environmental factors tend to be correlated with each other. Kids from deprived backgrounds may have poorer diets and get less sleep and get less attention from their parents. How do we work out which of these is having the most effect on their brains and their behaviour?

We need to understand which influences are actually impacting on the kids’ development to best intervene through allocation of resources and changes in government policy. The new findings in neuroscience may help us pin down exactly which factors most impact on our children’s development.