Jose-Luis Olivares/MIT. The effects of growing up in poverty can be seen in the brains of 12 to 13-year-old children

Brain scans of students from contrasting backgrounds have made visible the legacy of a challenging childhood. Important brain regions are more developed among children raised in a comfortable home environment. The enhanced regions are ones that are most required for tests such as the SAT.

"Just as you would expect, there's a real cost to not living in a supportive environment,” says MIT's Professor John Gabrieli. “We can see it not only in test scores, in educational attainment, but within the brains of these children."

Gabrieli led a team that used MRI machines to study the brains of 23 students from lower income families and 35 raised with more wealth. All were aged 12 or 13, with low income defined by eligibility for the subsidized school lunch program.

The children were also given the Massachusetts Comprehensive Assessment System (MCAS). Unsurprisingly, the lower income children performed worse on average, with 57% achieving proficiency compared to 91% of the wealthier students.

However, Gabrieli was also able to see the differences in the children's brains, noticing that the richer students had thicker temporal and occipital lobes, which is responsible, among many other capacities, for vision and storing knowledge. Important as these skills are in general, they are particularly emphasized in standardized tests. Differences in cortical thickness could account for almost half the difference in the students' MCAS scores, the researchers report in a paper published in Psychological Science.

Previous studies have linked environmental conditions to changes in the brain, and many more have associated the same conditions with lower academic outcomes, but this is the first to put the three together.

Income is certainly not the only important environmental influence on academic achievement. A poor but supportive home is better than a rich but abusive one. Nevertheless, co-author Martin West of Harvard says, “The gap in student achievement, as measured by test scores between low-income and high-income students, is a pervasive and longstanding phenomenon in American education, and indeed in education systems around the world.” Moreover, in the United States, the gap is widening.

However, teasing apart the multiple paths through which low incomes can hamper performance is hard, and being able to witness the effects on the brain may help educators assess the relative importance of different factors. Possible explanations include differences in nutrition, stimulation and stress. There is also debate as to when the differences occur, with a study starting to see how much difference is made by a substantial income boost for struggling parents in their child's first three years of life.

“To me, it’s a call to action. You want to boost the opportunities for those for whom it doesn’t come easily in their environment,” says Gabrieli. “There’s so much strong evidence that brains are highly plastic. Our findings don’t mean that further educational support, home support, all those things, couldn’t make big differences.”