Role of gut microbiome during infancy depends on whether child is girl or boy

It is well-established that there is a link between the gut microbiome and behaviors like depression, anxiety, and attention-deficit hyperactivity disorder. Until now, however there has been little human data from which to characterize the role of the microbiome in behavior during infancy, and how they may differ in boys and girls.

A direct and sex-specific association between the composition of an infant’s microbiome and early childhood behavioral health has been found by scientists at Dartmouth University.

“Prior research used participants who were already exhibiting depressive or anxious symptoms,” explains Hannah Laue, ScD, a research associate at Dartmouth’s Geisel School of Medicine, in a statement. “We wanted to look very early on, before these behaviors were expressed, to see if we could establish if the microbiome was influencing the neurobehavior, or if it was the other way around.”

During infancy, the microbiome and the brain are in their most rapid periods of development, and the brain may be particularly susceptible to changes in the microbiome.

Determining whether differences in the infant microbiome were related to neurobehavior, and whether that behavior varied in boys and girls—the study team used data from the New Hampshire Birth Cohort Study of 2009. It involved longitudinal follow-up of the developing microbiome beginning at birth, to understand its influence on the health and well-being of children.

For the study, the researchers analyzed stool samples from 260 infants at intervals in development—six weeks, one year, and two years. They characterized the species of microbes present in each participant’s gut and their functions. To assess behavioral development, they used the Behavioral Assessment System for Children, which measures clinical and adaptive behaviors in children and young adults.

The study team established that microbiome changes occur before behavioral changes. Infant and early-childhood microbiomes were related to behaviors such as anxiety, depression, and hyperactivity. They varied by time and sex.

“We found that increased diversity of the microbiome in the gut was associated with fewer behaviors like anxiety and depression in boys, but not among girls,” says Laue.  “We saw differences in social behaviors with microbiomes measured at later stages, where there was evidence that diversity, again, could be beneficial for boys but not for girls. And we found there were differences in certain species of bacteria and the essential functions they performed—such as the synthesis of vitamin B—that were related to these outcomes, as well.”

Their findings did not identify a microbial species that can immediately be used to help prevent children from developing behaviors such as anxiety or depression, “We think future studies can look a little more deeply at some of our specific findings and clarify whether they could be developed as probiotics,” says Laue.


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About the Author

Dr. Faith Coleman

Faith A. Coleman MD
Dr. Coleman is a graduate of the University of New Mexico School of Medicine and holds a BA in journalism from UNM. She completed her family practice residency at Wm. Beaumont Hospital, Troy and Royal Oak, MI, consistently ranked among the United States Top 100 Hospitals by US News and World Report. Dr. Coleman writes on health, medicine, family, and parenting for online information services and educational materials for health care providers.

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