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Unconditional income assistance for mothers living in poverty may have a positive effect on babies' brain activity, early results of a randomized study suggested.

In a subsample of the Baby's First Years trial, babies born to mothers who received a monthly $333 cash gift had higher absolute power in electrical brain activity in the mid- to high-frequency range at 1 year compared to babies born to mothers given $20 per month, reported Kimberly Noble, MD, PhD, of Columbia University in New York City, and colleagues.

According to their findings in the , babies in the high-cash group had higher absolute power on electroencephalography (EEG) in the alpha (8-13 Hz), beta (12-32 Hz), and gamma (33-100 Hz) frequency bands, but no difference for the low frequency band theta (4-8 Hz):

• Alpha: effect size [ES] 0.17, β=0.720, P=0.07
• Beta: ES 0.26, β=0.414, P=0.02
• Gamma: ES 0.23, β=0.221, P=0.04
• Theta: ES 0.02, β=0.396, P=0.84

However, the researchers noted that differences in absolute power (the amount measured on EEG within a certain frequency band) were not statistically significant after Westfall-Young multiple-testing adjustments. Differences in relative power ("absolute power as a fraction of power summed across all frequency bands") were similar, but smaller, the researchers observed, with none reaching statistical significance in either the unadjusted or Westfall-Young analyses.

"On balance, though, we judge that the weight of the evidence supports the conclusion that monthly unconditional cash transfers given to the mothers in our study affected brain activity in their infants," the group wrote. "This is notable because the patterns of neural activity we observe in the high-cash gift group have been correlated with higher language, cognitive, and social-emotional scores later in childhood and adolescence."

The is a randomized controlled trial measuring the impact of income assistance in child development, and included 1,000 low-income mothers who had recently given birth in New York City, New Orleans, Minneapolis/Saint Paul, and Omaha, Nebraska from May 2018 to June 2019. All infants were healthy at birth. After 1 year, EEGs were performed on 435 infants (data collection was cut short by the pandemic).

As children grow, they experience a decrease in brain power in the low frequency range and an increase in brain power in the mid- to high-frequency range, the researchers explained. Higher absolute and relative power in the low frequency bands have been associated with , while higher absolute power in the mid- to high-frequency bands has been associated with .

The results "[highlight] the importance of centering children's development and well-being at the forefront of policy considerations," argued Noble and colleagues.

"Debates over income transfer policies directed at low-income families in the United States have centered on maternal labor supply rather than child well-being," they wrote. "Our findings underscore the importance of shifting the conversation to focus more attention on whether or how income transfer policies promote children's development."

Study Details

Participating mothers in the study were randomly given unconditional cash transfers of either $333 per month or $20 per month for 12 months. Average household income of the study participants was $22,739 in the low-cash group $20,312 in the high-cash group. The majority of mothers were either Black (39-47%) or Hispanic (40-41%).

EEGs were performed on 251 infants in the low-cash group and 184 in the high-cash group. Children were an average 13 months of age at the time of their visit. Half of the infants in the low-cash gift group were girls versus 44% in the high-cash gift group.

Discussing some of the limitations of their work, Noble's group cautioned that their results capture only the first year of a multi-year trial.

"We do not suggest that a 12-month intervention alone would be likely to have lasting effects, nor that cash transfer policies obviate the need for direct service interventions, such as well-child pediatric visits, home visitation, or high-quality early childhood education," they said.

Additionally, they noted that the reduced sample size decreased the precision of estimates and also added that the degree to which individual differences in infant's brain power remain stable over time is unknown.

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