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Giving low-income families more money changes a child’s brain activity, and the effect can be seen by a child’s first birthday.

“Neuroscientists have described links between a child’s socioeconomic background and the structure of the brain,” says at Columbia University in New York. “But all that work has been correlational to date.”

Instead, Noble and her team are looking at how exactly child poverty causes reduced grey matter volume in the hippocampus and frontal cortex, which is associated with the subsequent development of thinking and learning. These changes have been seen throughout childhood and adolescence.

They are currently tracking development in the brains of 1000 babies from low-income families in four metropolitan areas: New York City, greater New Orleans, Minneapolis–Saint Paul and Omaha.

Each family had an average annual income of just over $20,000. The families entered the study in 2018 and 2019, and Noble’s team will continue to track the children until their fourth birthday.

The team gave half the babies’ mothers a monthly stipend of $333 and the other half $20 a month. The first payment was received soon after their baby’s birth. “They can spend the money however they want – no strings attached,” says Noble.

Noble says they chose to give $333 a month because that adds up to about $4000 a year, which studies suggest is an increase in wealth that has been linked with improvements in a child’s school performance later in life.

By July 2020, the babies had reached their first birthday. Just before or soon after turning 1, 435 of the children had their brain activity recorded using EEG – about 40 per cent were in families receiving $333 a month and 60 per cent were in families given $20 a month. The team couldn’t take recordings from all 1000 due to complications caused by the covid-19 pandemic.

The researchers found that, on average, children from families that received $333 a month had more brain activity in higher frequencies than those in the $20 group. “We know in childhood that more of that fast brain activity tends to predict skills that are important for thinking and learning down the road,” says Noble. “We also know that kids growing up in poverty often show less of that high-frequency brain activity.”

“We’re showing for the first time that poverty reduction has a causal impact on brain activity,” she says.

She speculates that $333 a month changed the home environments of those babies, though the researchers haven’t yet determined what exactly these changes were, and therefore how they affected brain activity. Lower incomes have been linked with , which in turn harms the development of a child’s brain.

“The fact that we did see effects after just one year really speaks to the remarkable plasticity of the developing brain and its sensitivity to economic resources,” she says.

“We need to develop understanding of how a child’s brain develops and matures,” says at the University of Birmingham in the UK. “We need to better understand the biological, psychological and social factors that influence brain development. This kind of approach, using a method in EEG that can be applied in even very young children and in large cohorts, could help to achieve those goals.”

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