Moms who said their incomes were never enough also tended to have lower levels of income and education, more stressful life events, and higher overall stress. But even after the scientists accounted for these other factors, income insufficiency still showed a unique association to how well babies’ brains developed.
The scientists focused most closely on brain features that typically develop quickly in the first year of life, and show up on EEGs in alpha and beta ranges, linked in other research to later cognitive development in areas such as executive function, language, and attention. Babies whose moms said their incomes were rarely or never sufficient generally showed slower increases in alpha power, slower increases in alpha peak frequency—a classic marker of maturation in infancy—and consistently lower beta power. These differences were noticeable when the babies reached around 9 months of age.