A new NIH-funded study suggests that children from low-income environments are more likely to have neurological impairments. The researchers claim that these neurodevelopmental issues are “distinct from the risk of cognitive and emotional delays known to accompany early-life poverty.”
The study is based on data gathered between 1959 and 1974 of 36,443 pregnant participants from diverse socioeconomic backgrounds in the US. The researchers looked at physician reports of neurologic abnormalities in the children at four months, one year, and seven years. The study authors explain that the older methods used to diagnose neurological impairments at the time the data was collected, while not as accurate as techniques available today, are still a reliable source of information for the present analysis.
Identifying socioeconomic class through patient interviews about education level, employment status, and the number of parents living in the home, the researchers divided the infants into three groups corresponding to low, medium, and high levels of socioeconomic disadvantage. After controlling for the increased risk of pregnancy complications and other risk factors, they found that children with the highest risk for socioeconomic disadvantage were more likely to be diagnosed with a neurological abnormality at four months and that this risk increased over time.
Almost thirteen percent of those in the highly disadvantaged group were diagnosed with such an abnormality at four months, compared to a little over nine percent of those in the low-risk group. By age seven, the likelihood increased to 20.2% for the most disadvantaged while only 13.5% in the low-risk group received such a diagnosis.
“The size of the effect we saw was modest,” said the study’s senior author, Stephen Gilman, Sc.D., acting chief of the Health Behavior Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). “However, the findings do indicate that an impoverished environment may pose a hazard for a child’s developing nervous system.”
The study, published in the International Journal of Epidemiology, points out that the increased level of neurological impairment that appears to result from socioeconomic disadvantage can often lead to another diagnosis late in life, including those for learning disabilities, ADHD, anxiety disorders, and schizophrenia.
Stephen E Gilman et al. Socioeconomic disadvantage and neural development from infancy through early childhood. International Journal of Epidemiology, December 2015. (Abstract)