Poverty may prove to be an especially poor home for a maturing central nervous system to grow up in, suggests a new study funded by the National Institutes of Health (NIH) and partners.

The study, published Wednesday in the International Journal of Epidemiology, found that the children of families with low socioeconomic status were more likely to harbor signs of neurological impairment than children from more privileged backgrounds. Worse still, these gaps in functioning between the two groups, though small, only appeared to grow larger as the children became older. That might leave the poorest children the most vulnerable to later learning difficulties or mental health problems.  

"The size of the effect we saw was modest," explained senior author Dr. Stephen Gilman in a statement. "However, the findings do indicate that an impoverished environment may pose a hazard for a child's developing nervous system." Gilman is also acting chief of the Health Behavior Branch at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

Gilman and his colleagues pored over data from the NIH-sponsored Collaborative Perinatal Project (CPP), one of the lengthiest and most extensive studies aimed at understanding the factors behind neurologic conditions in children. Enrolling around 42,000 pregnant women from 1959 to 1965, the CPP additionally kept track of over 50,000 born children, with the study formally ending in 1974. As part of the CPP, children were given rigorous neurological examinations at various points of their lives, extending from birth to around 7 years of age.  

When the researchers separated the CPP children (36,433 in total) into three broad tiers of socioeconomic status, they failed to notice any difference in neurological functioning between the groups at birth. Only as they grew up did these differences begin to magnify. At 4 months, the 12.8 percent of the lowest tier showed signs of impairment, compared to 9.3 percent of the highest. At age 7, it was 20.2 percent vs 13.5 percent.

Growing up in poverty has long been tied to an increased risk of cognitive delay in children, in part due to the greater rate of pregnancy complications among low-income mothers. According to the researchers, though, the same explanation wouldn’t fully account for their current findings. They do theorize that higher levels of maternal stress hormones or drug/alcohol use during pregnancy among these mothers may be possible factors. The greater rates of child abuse or poor parental mental health among low-income families might similarly influence development after birth as well.  

Though neurological impairments can manifest in a variety of ways, some common symptoms include poor coordination, difficulty reading and writing, and epilepsy. As the rate of childhood poverty has only increased since the original CPP study, the researchers advocate further research on better understanding the link between poverty and proper nervous system development. It’s research that might hopefully lead to targeted interventions aimed at protecting children's brains right from the very start, 

Source: Chin-Lun Hung G, Hahn J, Alamiri B, et al. Socioeconomic disadvantage and neural development from infancy through early childhood. International Journal of Epidemiology. 2015.