After scanning the brains of more than 1,000 individuals, scientists have found a relationship between brain size and socioeconomic status in children and adolescents. According to the study, certain brain regions, in particular those involved in language and decision-making, tended to be smaller in those from poorer and less educated families than those from affluent backgrounds. Although the study was correlational, the researchers are hopeful that the findings may bring about positive changes to antipoverty measures that could make a real difference to those from disadvantaged backgrounds. The study has been published in Nature.
Our brains are products of both genetics and the environment, and childhood experiences are known to be critical for shaping its development. It’s therefore no surprise that children from families with a higher socioeconomic status—a position based on education, income and occupation—tend to do better in school and outperform those from poorer backgrounds in various measures of cognition.
Although studies have attempted to probe this relationship further by comparing the brains of children from different backgrounds, which did indicate differences, these have been limited because they failed to adequately discriminate between socioeconomic status and race. Furthermore, they didn’t investigate factors like income and education separately, which is important since these likely have different effects.
In an attempt to overcome these important issues, a group of researchers from nine institutions across the U.S. conducted a large study aimed at investigating the effects of both family income and parental education on brain structure in children and adolescents, independently of genetic ancestry. For the study, the researchers enrolled 1,099 typically developing individuals between the ages of 3 and 20. After collecting data on participants’ socioeconomic status, the researchers imaged their brains using MRI and also conducted various cognitive tests.
The researchers found a strong association between family income and brain surface area, particularly in regions of the cortex known to be involved in things like language, reading and executive functions, or the higher cognitive skills used to control other cognitive processes, such as problem solving and memory.
Those from families with an income exceeding $150,000 (£101,000) were found to have around 6% more cortical surface area than those from families who bring home less than $25,000 (£17,000) annually. Income differences of just a few thousand dollars were also linked with major differences in brain surface area in those from the poorest families. But the relationship didn’t end there; those from poorer backgrounds, and hence those with smaller cortical surface areas, also tended to do worse on cognitive tests, particularly those designed to assess executive functions.
The researchers also identified a relationship between brain morphology and parental education, with those from highly educated families tending to have a larger hippocampus, a region primarily involved in learning and memory.
While correlation cannot imply causation, the researchers have put forward a few ideas that could explain the observed differences. Those from lower income families may have a worse diet and poorer access to things like healthcare, good schools and play areas than those from more affluent families. Family environments may also be more stressful in those from poor backgrounds, and they may live in more polluted areas.
But the researchers stress that a smaller brain is not an inevitable consequence of growing up in a disadvantaged background, and they believe that interventions such as improving access to health and child care and providing better food in schools could make a real difference.