The research could have policy implications as President Biden pushes to revive his proposal to expand the child tax credit.
WASHINGTON — A study that provided poor mothers with cash stipends for the first year of their children’s lives appears to have changed the babies’ brain activity in ways associated with stronger cognitive development, a finding with potential implications for safety net policy.
The differences were modest — researchers likened them in statistical magnitude to moving to the 75th position in a line of 100 from the 81st — and it remains to be seen if changes in brain patterns will translate to higher skills, as other research offers reason to expect.
Still, evidence that a single year of subsidies could alter something as profound as brain functioning highlights the role that money may play in child development and comes as President Biden is pushing for a much larger program of subsidies for families with children.
“This is a big scientific finding,” said Martha J. Farah, a neuroscientist at the University of Pennsylvania, who conducted a review of the study for the Proceedings of the National Academies of Sciences, where it was published on Monday. “It’s proof that just giving the families more money, even a modest amount of more money, leads to better brain development.”
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Another researcher, Charles A. Nelson III of Harvard, reacted more cautiously, noting the full effect of the payments — $333 a month — would not be clear until the children took cognitive tests. While the brain patterns documented in the study are often associated with higher cognitive skills, he said, that is not always the case.
“It’s potentially a groundbreaking study,” said Dr. Nelson, who served as a consultant to the study. “If I was a policymaker, I’d pay attention to this, but it would be premature of me to pass a bill that gives every family $300 a month.”
A temporary federal program of near-universal children’s subsidies — up to $300 a month per child through an expanded child tax credit — expired this month after Mr. Biden failed to unite Democrats behind a large social policy bill that would have extended it. Most Republicans oppose the monthly grants, citing the cost and warning that unconditional aid, which they describe as welfare, discourages parents from working.
Sharing some of those concerns, Senator Joe Manchin III, Democrat of West Virginia, effectively blocked the Biden plan, though he has suggested that he might support payments limited to families of modest means and those with jobs. The payments in the research project, called Baby’s First Years, were provided regardless of whether the parents worked.
Evidence abounds that poor children on average start school with weaker cognitive skills, and neuroscientists have shown that the differences extend to brain structure and function. But it has not been clear if those differences come directly from the shortage of money or from related factors like parental education or neighborhood influences.
The study released on Monday offers evidence that poverty itself holds children back from their earliest moments.
“This is the first study to show that money, in and of itself, has a causal impact on brain development,” said Dr. Kimberly G. Noble, a physician and neuroscientist at Teachers College, Columbia University, who helped lead the study.
Dr. Noble and colleagues from six universities recruited a thousand mother-infant pairs within days of the babies’ birth and randomly divided the families into two groups. One group received a nominal $20 a month and
