Too many antibiotics early in childhood may impact brain development

NEW BRUNSWICK, N.J. — The average child in the United States receives around three different antibiotic treatments before reaching their second birthday. Now, researchers from Rutgers University find that exposure to antibiotics early in life may actually mess with brain development in areas responsible for both cognitive and emotional functioning.

On a more detailed level, this new research indicates that penicillin is capable of changing both the body’s gut microbiome and elements of gene expression within key areas of the developing brain. The microbiome refers to the trillions of beneficial microorganisms and bacteria living within the human body. Gene expression, meanwhile, helps cells respond and adapt to a changing environment.

Study authors believe their work makes a strong case for the reduction of widespread antibiotic use in order to avoid neurodevelopment problems. Troublingly, penicillin and other similar drugs such as ampicillin and amoxicillin are the most common antibiotics doctors prescribe for young children.

“Our previous work has shown that exposing young animals to antibiotics changes their metabolism and immunity. The third important development in early life involves the brain. This study is preliminary but shows a correlation between altering the microbiome and changes in the brain that should be further explored,” says lead author Martin Blaser, director of the Center for Advanced Biotechnology and Medicine at Rutgers, in a university release.

More evidence the ‘gut-brain-axis’ is key to health

Researchers made these findings by comparing two groups of mice. The team exposed one group to low-dose penicillin while still in the womb, while the second group was not. Rodents given penicillin showed significant changes within their intestinal microbiota. Additionally, those mice also displayed altered gene expression in the frontal cortex and amygdala of their brains. Both of those areas are essential to memory development, as well as fear and stress responses.

Study authors say it’s becoming more and more apparent that what happens within our stomachs and intestinal tracts influences brain signaling; a connection scientists call the “gut-brain-axis.”

If something disrupts this pathway however, it can lead to permanent structural and functioning changes in the brain. While unconfirmed, such disruptions may even lead one day to neuropsychiatric or neurodegenerative disorders years or decades down the line.

“Early life is a critical period for neurodevelopment,” Blaser adds. “In recent decades, there has been a rise in the incidence of childhood neurodevelopmental disorders, including autism spectrum disorder, attention deficit/hyperactivity disorder and learning disabilities. Although increased awareness and diagnosis are likely contributing factors, disruptions in cerebral gene expression early in development also could be responsible.”

Moving forward, more research is needed to conclusively determine if antibiotics indeed directly change brain development, as well as if microbiome molecules traveling to the brain end up disturbing gene activity and causing cognitive issues.

The study appears in the journal iScience.