Study: Kids of less-educated moms may have noisier brains

By: Elizabeth Landau, CNN
By: Elizabeth Landau, CNN

A mother's level of education has strong implications for a child's development. Northwestern University researchers show in a new study that low maternal education is linked to a noisier nervous system in children, which could affect their learning.

"You really can think of it as static on your radio that then will get in the way of hearing the announcer’s voice," says Nina Kraus, senior author of the study and researcher at the Auditory Neuroscience Laboratory at Northwestern University.

The study, published in the Journal of Neuroscience, is part of a larger initiative working with children in public high schools in inner-city Chicago. The adolescents are tracked from ninth to 12th grade. An additional group of children in the gang-reduction zones of Los Angeles are also being tracked. Kraus and colleagues are more broadly looking at how music experience, through classroom group-based musical experience, could offset certain negative effects of poverty. But first, they wanted to see what biological effects poverty may have on the adolescents' brain. In this particular study, 66 children -- a small sample -- in Chicago participated.

Those whose mothers had a "lower education" tended to have not graduated from high school. Kraus's study did not directly track income of families, but most children in the study qualified for free lunch (to be eligible, a family of four must have income of about $29,000 or less).

Researchers found "children from lower-SES (socioeconomic status) backgrounds are exposed to less complex and linguistically rich input in addition to hearing fewer words per hour from their caregivers," according to the study.

The new study shows that in a group of adolescents from inner-city Chicago, the nervous system is different, depending on an individual's mother's level of education-- both in the absence of stimulation, and when the brain is stimulated by sound. The same children who showed more "noise" in the nervous system performed worse on standardized tests of memory and reading. Researchers used scalp electrodes to measure the ongoing electrical activity in kids' brains.

Among children of less-educated mothers, study authors found more noise in the absence of sound, compared to those with mothers who had more education. Additionally, the nervous system's response to sound was less strong and less precise among children of less-educated mothers.

"You have this double whammy, if you will, of having a poorer signal coming through, and heightened background neural activity," Kraus said. "That’s a signal-to-noise disaster."

Kraus and colleagues also found that when children of lower-educated mother hear the same sound repeatedly, nervous system responses tended to vary, whereas those of more highly-educated mothers responded the same way each time.

"If the nervous system responds inconsistently to the same sound, how is a kid to learn what the sound means, because he’s getting this jittered input?" Kraus said.

Researchers saw that the sound waves and brain waves physically resemble each other, so they could see what components of the sounds a child's brain is processing, or not. "The implications are very important once, vis-a-vis education. It just reinforces the idea that education is important, not just for you but for your children," Kraus said.

You might be asking yourself: Is nature or nurture to blame? "It’s difficult to know where the deprivation starts," Kraus said. "The data here point to environmental causes."

Although this study did not measure other lifestyle factors directly, low maternal education is associated with poorer nutrition, less availability of books in the home, less exercise and less encouragement of children do their homework, Kraus said. All of these deficiencies could play a role in the development of a child's nervous system.

Previous research has also indicated that a mother's education matters in terms of a child's auditory development and auditory language enrichment, which is necessary for language skills to develop. A study by Betty Hart and Todd R. Risley found that by the time a child from a family on welfare is 3 years old, he or she will have heard 30 million fewer words than if the parents are professionals. By the fourth year, an average child in a professional family would have accumulated experience with almost 45 million words, compared to an average child in a welfare family (13 million words).

Welfare children tend to also hear far more discouraging language than those whose parents are professionals, the research showed. When young children aren't being exposed to a wealth of words, and the language they do hear is more negative than what their peers hear, their development can be noticeably different.

The researchers are interested to see what effect music education has on these children and the others in their study. Their hypothesis is that music will help, especially with strengthening language skills.

"In the same way as getting linguistic stimulation is a form of enrichment, because you are making sound-to-meaning connections all the time, and you are strengthening circuits in the nervous system that are important for language, music also strengthens many of these same circuits," Kraus said.

A second study released this week in JAMA Pediatrics shows poverty also affects the hippocampus and amygdala parts of children's brains.

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