“We’re finding the difference (in white matter growth) is on the order of 20 to 30 percent, comparing the breastfed and the non-breastfed kids.”
Babies who are breastfed show signs of early brain development, particularly in regions associated with language, emotional function, and cognition.
Researchers used specialized, baby-friendly magnetic resonance imaging (MRI) to look at the brain growth in a sample of children under the age of 4 years. By age 2, babies who had been breastfed exclusively for at least three months had enhanced development compared to children who were fed formula exclusively or who were fed a combination of formula and breastmilk.
This isn’t the first study to suggest that breastfeeding aids babies’ brain development. Behavioral studies have previously associated breastfeeding with better cognitive outcomes in older adolescents and adults.
But this is the first imaging study that looked for differences associated with breastfeeding in the brains of very young and healthy children, says Sean Deoni, assistant professor of engineering at Brown University.
“We wanted to see how early these changes in brain development actually occur,” Deoni said. “We show that they’re there almost right off the bat.”
Deoni leads Brown’s Advanced Baby Imaging Lab. For the study published in the journal NeuroImage, he and colleagues use quiet MRI machines that image babies’ brains as they sleep.
The MRI technique looks at the microstructure of the brain’s white matter, the tissue that contains long nerve fibers and helps different parts of the brain communicate with each other.
Specifically, the technique looks for amounts of myelin, the fatty material that insulates nerve fibers and speeds electrical signals as they zip around the brain.
Researchers looked at 133 babies ranging in ages from 10 months to four years. All of the babies had normal gestation times, and all came from families with similar socioeconomic statuses.
Babies were split into three groups: those whose mothers reported they exclusively breastfed for at least three months, those fed a combination of breastmilk and formula, and those fed formula alone. The researchers compared the older kids to the younger kids to establish growth trajectories in white matter for each group.
The exclusively breastfed group had the fastest growth in myelinated white matter of the three groups, with the increase in white matter volume becoming substantial by age 2. The group fed both breastmilk and formula had more growth than the exclusively formula-fed group, but less than the breastmilk-only group.
“We’re finding the difference (in white matter growth) is on the order of 20 to 30 percent, comparing the breastfed and the non-breastfed kids,” Deoni said. “I think it’s astounding that you could have that much difference so early.”
The researchers then backed up their imaging data with a set of basic cognitive tests on the older children. Those tests found increased language performance, visual reception, and motor control performance in the breastfed group.
The study also looked at the effects of the duration of breastfeeding. The researchers compared babies who were breastfed for more than a year with those breastfed less than a year, and found significantly enhanced brain growth in the babies who were breastfed longer—especially in areas of the brain dealing with motor function.
“I think I would argue that combined with all the other evidence, it seems like breastfeeding is absolutely beneficial,” Deoni says.
The National Institutes of Mental Health funded the study.