28 July 2015. Poverty has been linked to delayed or poor brain development. Thus, children from poor families get lower scores on standardized tests of academic achievement, and their grades in school and educational attainment are lower than those obtained by their better-off peers. Most recently, this was shown in a study that relied on magnetic resonance imaging of 389 US children and adolescents.
The findings suggest that about 20 percent of the gap in test scores between poor children and middle-class children may be a result of poor brain development in the upper-front and side regions of the brain known as the frontal and temporal lobes, respectively. Although there was a tendency toward greater deficits at decreasing family income levels, the main effect was seen in children and adolescents from the poorest households, i.e., below the so-called poverty level.
In an interview with Reuters Health, senior author Seth Pollak of the University of Wisconsin-Madison emphasized that children with other risk factors for poor brain development were excluded from the analysis, including those with low birth weights and attention problems. Accordingly, the study compares the healthiest children in the U.S. who – for the most part – differ only in terms of family income.
However, that may not be entirely true. According to the original study data, a total of 75 children were excluded due to an ADHD diagnosis, and only three due to “lead poisoning”. This number is surprisingly low, given the large number of subjects screened and the inclusion of data from 433 in the new study.
Could lead exposure have contributed to the findings of this study? As previously discussed at this site, pre-school lead exposure has been thoroughly documented as a causal factor in deficient school performance. While several studies also identified poverty as a risk factor, lead exposure seemed to be more important, at least in some communities. Children exposed to excess lead were also over twice as likely as children with lower exposure levels to be suspended from school. Such effects occur at exposure levels that used to be considered “low”, as has been shown in Massachusetts. Even when adjusting for poverty and school parameters, student test scores in elementary school were lower at elevated blood-lead concentrations. In addition, the recent reduction in childhood lead exposures was associated with clear improvements in test performance, where especially children in low-income communities benefited.
Environmental justice studies have demonstrated that poor neighborhoods are disproportionately exposed to greater levels of environmental toxicants, including air pollution and several chemical brain drainers. So being poor is not just a matter of having a low income.
There is one more issue that needs to be considered. In the new study, lower gray matter volumes on the magnetic resonance scans were associated with poverty – but could that be due to toxic chemicals? Indeed, decreased gray matter volumes have been documented in adults with elevated lead exposure in childhood. Also, prenatal exposure to chlorpyrifos, a common pesticide, is associated with thinner gray matter at school age. Developmental exposure to such toxicants is more likely in children from poor families.
Thus, the new research linking poverty to poor school records and less gray matter in the brain fails to document that it is poverty as such that causes the brain drain. While it is true that children from poor families may not be prepared when they get to school, because they are hungry or tired, there is more to it than poverty-stricken parents failing to feed and care for their children. Developing brains will likely suffer under poverty conditions, but social support for poor families needs to be complemented by preventing exposures to chemical brain drainers.