U.S. Kids Are Falling behind Global Competition, but Brain Science Shows How to Catch Up

U.S. Kids Are Falling behind Global Competition, but Brain Science Shows How to Catch Up thumbnail

On vital measures that predict later success in school and life, small children in the U.S. do worse than kids in comparable countries. This distressing information comes from an Organisation for Economic Cooperation and Development (OECD) study of five-year-olds. For years the OECD has been examining the academic achievement of 15-year-old students from around the world, and recently it extended this work to the younger group. The average American child had lower literacy and numeracy scores, exhibited poorer self-regulation skills and engaged in fewer prosocial behaviors than children from Estonia and England. Just about the only bright spot was that U.S. children were roughly equivalent to their international peers on some–but not all–social-emotional measures.

These findings did not get the attention they deserved, because they were announced in March 2020, a few days after the World Health Organization declared that COVID had become a pandemic. They were not surprising, however. Recent research has shown that approximately half the American children are not on track “ in at minimum one critical area of school readiness. The OECD report, which was based on children just starting school, was a powerful reminder of something fundamental: Learning begins the first day of your life. The best years of a child’s life are filled with opportunities. The earliest years of a child’s life are a time when their brain is more open to new experiences and more plastic. Nearly 85 percent of brain growth occurs between birth and the age of three. One million neural connections are made every second during this time.

Two decades of child development research tell us that small kids need two things above all else to get off to the best possible start: nurturing interaction with caregivers and protection from toxic stress. A new wave of neuroscientific research has highlighted the neurobiological effects that early experience has on children’s brains over the past five years. This has strongly suggested ways to achieve these goals. This research gives us a glimpse into the brains of young children. Studies show that the brain’s parts that support language and cognitive development are more active and connected when we have positive relationships and environments.

One of us (Suskind), is a pediatrician and early-learning researcher. He has been following the evolution of brain science to inform not only what we do as parents, but also how society can benefit. Paid leave, for example, gives parents the opportunity to build nurturing relationships. Tax credits and child allowances can help alleviate poverty that is known to be harmful to development. when parents work from home, a large majority of American mothers must have access to quality child-care. This provides young children with responsive and engaged caregivers.

But there is a disconnect between science and society’s knowledge of what children need. The United States is the only developed nation that doesn’t require paid parental leave after childbirth. In 2020 four in 10 children in the U.S. had families who were struggling to afford basic necessities. Congress just allowed the expanded child tax credit to expire. This credit helped millions of families weather the pandemic, and dramatically reduced the number of children who were poor. Further, approximately half of Americans live in so-called child care deserts, where there aren’t nearly enough facilities or caregivers, and fewer than 10 percent of existing child care programs are considered high quality. These gaps were highlighted by the pandemic. It was like a powerful earthquake that left behind aftershocks. It showed how fragile our nation’s support of parents and children.

The science of brain development is not often discussed in public discussions about ways to close these gaps. It should be part of the conversation, as it provides a roadmap to improve both national and local policies that can improve children’s lives.

The Many Effects of Language

Wearing his Chicago Bulls cap, Randy sat down on the soft carpet in his living room and pulled his son Julian, two, into his lap.

“Want play?” he inquired.

Julian smiled and began stacking blocks. Father and son tallied up the numbers (“one, two, three, four, five …”) until they saw a tall tower.

“Drop It, Drop It.” Randy nudged Julian and encouraged him to tip the tower. As Randy added more blocks, Julian looked at his father with delight. When the stack–and the counting–reached 16, the tower came crashing down.

“Boom!” Randy shouted.

“Boom!” Julian echoed.

Randy was a fully-embracing parent. He signed up for a Chicago-area home-visiting program to learn more about child development. To protect the privacy of the family, we are only using first names. He was listening to his child and talking to him. This kind of rich language input is central to the importance of nurturing relationships. For years researchers focused on the quantity of words a child heard–the so-called 30-million-word gap–as the best predictor of language development. New research shows that language exposure is even more important. It is not enough to just hear conversations. As Randy encouraged Julian, children must take part.

In a 2018 study, which was the first of its kind, researchers at Harvard University and the Massachusetts Institute of technology put 36 four- to six-year-old children in a brain scanner and told them stories about playing hide-and-seek and opening birthday presents. While the kids listened, the scientists looked at brain structure and function. To get an idea of the language environment, the researchers had previously recorded the conversations for two days.

Children with more language and more conversational turn taking were more likely to activate key language areas in their brains when they heard stories through the scanner. These kids also showed stronger connections between language areas that govern speech perception and speech production. Rachel Romeo, a speech language pathologist and neuroscientist, said that at every socioeconomic level, there was more conversation. This is because more mature brain development is associated with more conversation. She is currently at the University of Maryland.

Other research shows that caregivers and very young children have important neural connections. Their brains sync up. This was discovered by Elise Piazza, a Princeton University Neuroscience Institute colleague. They used functional near-infrared spectrumroscopy to track the activity neurons. The scientists looked at adults and infants between nine and 15 months old, in a variety of situations. The brain waves of the infants were synchronized with the adult when they were playing together or paying attention to the exact same object. They did not sync when the adult spoke to another person in the room. This confirms that overheard language does NOT count. This kind of synchrony has been linked to social learning, problem-solving skills and vocabulary development. The adult was able to anticipate smiles and interest from the baby when they were in sync.

” We knew that infant-directed speech was very important for babies’ learning, and that a variety of communicative clues could be helpful for them,” Piazza, now at the University of Rochester, says. But “even before they’re fully verbal, there are a lot of ways in which [babies’] brains are picking up on these different cues in the environment.”

This research strongly supports parents’ need to spend time with their children. This research also highlights the importance of parents having access to affordable, high-quality child care. Randy and millions of others like him had to deal with the fact that they rarely had enough time to raise their children in the way they wanted. He was working multiple jobs to make ends meet. Mayra, his wife, also worked full-time. Most days Randy saw his kids for all of 30 minutes. Randy couldn’t afford custodial care. He often found Julian staring at a loud television in his pickup. Romeo states, “Here we see this body of research proving over and over again that the core adult-child interactions during the early years are crucial for brain development and socialization.” “Anything we can do as a society to create an environment where [those] relationships can flourish, that’s the best investment we can make in children’s futures.”

Charts show results of a study comparing effects of paid and unpaid maternal leave on toddlers’ language skills and behavior.
Credit: Amanda Montanez; Source: “Paid Maternal Leave Is Associated with Better Language and Socioemotional Outcomes during Toddlerhood,” by Karina Kozal et al., in Infancy, Vol. 26; July/August 2021

Early Help for Parents

Language represents just one dimension of the strong nurturing interactions between caregivers and children. Connections begin for infants on the first day. This is why paid leave at childbirth is consistent with policies that promote brain development in the early years. Few Americans have this kind of leave. Randy and Mayra did not have it. After their children were born, Mayra was among the approximately one quarter of mothers who returned to work within two weeks. Randy only took a day or two off each week.

Traditionally, research on paid time has focused on the economic aspect of the equation. This includes assessing the impact on incomes and employers. Yet more recently, studies of the effects of paid leave on the health of mothers and children found it was associated with lower levels of postpartum depression, improved infant attachment, decreases in infant mortality and rehospitalizations, as well as increases in pediatric visits, timely immunizations and the duration of breastfeeding. Payed leave for fathers at childbirth can benefit both parents’ mental health by reducing stress and depressive symptoms. Married parents who take paid leave together are less likely to divorce.

To this already convincing evidence, the newest research adds positive impacts of paid leaves on infants’ cognitive developmental. In 2021 developmental psychologist Natalie Brito of New York University and her colleagues published a study of 328 mothers and babies from across the socioeconomic spectrum, some of whom had paid leave and some of whom had unpaid leave at the birth of their child. The researchers asked mothers to report on the language abilities and emotional reactions of their children in social situations when their children were two years old. Paid leave was associated with higher language skills for the toddlers at all socioeconomic status (SES) levels and with better emotional skills among children whose mothers had lower education levels. Brito states that paid leave may not be beneficial for all families, but it could have a significant effect on lower-SES families.

Paid leave actually changes patterns of brain activity. In a second study of 80 mothers and babies published this past April in Child Development, Brito and her colleagues used electroencephalography (EEG) to eavesdrop on babies’ brain waves three months after birth. These waves are created by interactions between neurons. Both high-frequency and low-frequency waves are important for everyone. As children age, their high-frequency activity tends increase. Studies have shown that children who are exposed to higher frequencies in their early years of life tend to score higher on skills needed for learning and thinking.

Brito and her colleagues found that infants whose mothers were able to take paid leave had higher frequency waves than those whose mothers were unable to. Although the sample was small and not random, the researchers did control other variables such as maternal education, maternal relationship status, gestational age at delivery, number of children living at home, and occupational prestige. The association between paid leave and brain-wave patterns persisted, explaining 12 to 30 percent of the variance in infant brain activity.

Although it is difficult to determine the causes of these differences, stress among mothers could be one reason. The mothers’ hair was measured for cortisol levels. This hormone is linked to stress and can increase as psychological or physical stress builds up. Mothers on paid leave had lower levels of cortisol than mothers who were not on leave. They also scored higher on tests of maternal sensitivity that measured parent-child interaction. Brito suggests that paid leave can reduce stress. It also provides financial stability and resources. This could indirectly impact the way parents parent or interact with their children. These are the first studies of this kind and don’t prove cause-and-effect. But, as Brito says, “some of these dots have started to be connected.”

Solutions for the Future

We know that very young children thrive when they are safe from toxic stress and have predictable and stable lives. Brand-new research has turned up higher risks of developmental delays in babies born during the COVID pandemic, which some experts suspect may be related to higher stress levels in their mothers. For decades, we know that children who grow up in low-income families are more likely to be faced with these kinds of distressing and unpredictable situations.

More recently, neuroscientists began exploring what poverty does to children’s brains. In a 2015 study of more than 1,000 children between the ages of three and 20, neuroscientist Kimberly G. Noble of Teachers College at Columbia University and her colleagues found a consistent relationship between cortical surface area (which is associated with cognitive ability) and socioeconomic factors. This study and others have shown that the brain areas that deal with language, executive function, and memory show the greatest differences.

For instance, in 2019 Noble and her colleagues, also using hair cortisol levels as markers of chronic stress, showed that higher levels were associated with smaller hippocampi, a part of the brain integral for memory. These changes could be an adaptive response. The brain is constantly waiting for instructions. If a child grows up in toxic stress environments, their brain will be highly reactive to stress. These changes can lead to problems later in life, both in education and in employment.

Tax credits for families with young children have the most potential to reduce rates of childhood poverty, according to a 2019 National Academy of Sciences report. These credits were evident during the pandemic when an expanded tax credit led to a significant reduction in childhood poverty rates. The credit was free from earnings for the first time. This benefit was both for those who worked and those who wanted to stay at home with their children. More than 90 percent of American children were eligible.

But at the end of 2021 the closely divided U.S. Senate refused to extend this program. When the credits ran out, between December 2021 and January 2022, the childhood poverty rate spiked from 12 to 17 percent, higher than before the pandemic. This resulted in an additional 3.7 million children being forced into poverty. According to the NAS report, the long-term effects of childhood poverty on adult employment, crime rates and population health cost the U.S. between $800 billion and $1.1 trillion annually, whereas a set of policies centered on tax credits plus nutritional supplements and a few other programs would cut childhood poverty by 50 percent and ultimately cost the country less.

We also know a lot more about child care. The U.S. supports a high-quality system of universal child care centers that is run by the Department of Defense for military family members. About 30 years ago military child care was as bad as the worst we see today. People working in the military had to worry about who was looking after their children. This could have a negative impact on their performance. The Pentagon redesigned these programs to increase professional development and pay, enforce high standards of care and limit costs for families. The European countries are known for their wide-spread access and high quality care. The OECD study of five year-old children in England and Estonia shows that both countries have generous paid leave and almost universal preschool programs.

Creating something similar in the U.S. will not be cheap. Congress failed to pass legislation last year that would have subsidized child-care costs for most working families and provided adequate wages for child-care providers. The price tag would have been $400 billion. It might seem high, but it is nothing compared to the cost of inaction. A report by ReadyNation, a not-for-profit group started by business executives to research education, found that child care problems cost the U.S. $57 billion a year in lost earnings, productivity and revenue. It has also been estimated that if American women stayed in the workforce at a rate similar to that of Norway, which has paid leave and government-subsidized child care, the U.S. could add $1.6 trillion to the gross domestic product.

With no paid leave, limited child care, and no child credits, it is clear that there is a huge gap between what science says children need and what U.S. policies do for them. It is time to use the wealth of scientific evidence that we have to guide our policies. Healthy brain development is the foundation of our country, as it is our future. This means that we as a society cannot do more than to foster and protect our children’s brain development.

This article was originally published with the title “The Path to Better Childhoods” in Scientific American 326, 6, 48-53 (June 2022)

doi: 10. 1038/scientificamerican0622-48



    Dana Suskind, a childhood-learning researcher and pediatric cochlear implant surgeon at the University of Chicago Medical Center, is co-director of the TMW Center for Early Learning Public Health. She is co-author of Parent Nation: Unlocking Every Child’s Potential, Fulfilling Society’s Promise (Dutton, 2022).

    Credit: Nick Higgins


      Lydia Denworth is a Brooklyn, N.Y.-based science writer and a contributing editor for Scientific American. She wrote about the neuroscience of stutter

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