Scientists have uncovered a new link between a baby’s early biological development, gut bacteria, and future brain health. The research suggests that certain microbes in the gut may influence the risk of neurodevelopmental conditions such as autism spectrum disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD).

The study, published in Cell Press Blue, explored how changes in a baby’s genes at birth may interact with the gut microbiome during infancy. Researchers found that some bacteria may have a protective effect, opening new possibilities for future diet-based approaches and probiotics, as per a report by Science Daily.

How are gut bacteria linked to brain development?

The first years of life are a crucial stage for brain growth and immune system development. Scientists have long known that both epigenetics and the gut microbiome can affect health, but the way these two systems interact early in life has remained unclear.

Researchers from The Chinese University of Hong Kong investigated whether a baby’s biological changes at birth could influence gut bacteria development and later neurodevelopmental outcomes, as per a report by Science Daily.

“We wanted to see how the epigenome and microbiome interact in early life and if their interaction could influence a child’s risk of developing neurodevelopmental conditions like ASD and ADHD,” says co-senior author and public health researcher Hein Min Tun of The Chinese University of Hong Kong.

The team discovered that a baby’s epigenetic patterns at birth may affect how the gut microbiome develops. At the same time, certain beneficial bacteria appeared to modify the potential risk linked with some biological markers.

“We discovered a kind of conversation happening: a baby’s epigenetic setting at birth can influence their risk for neurodevelopmental disorders, but the presence of certain ‘good’ bacteria in their gut can step in and modify the risk.”

What did researchers examine in infants?

To understand the connection, scientists studied DNA methylation patterns, a type of epigenetic change, from umbilical cord blood collected from 571 infants.

They also analyzed gut microbiome samples from 969 infants at two, six, and 12 months of age. Researchers additionally examined microbiome samples from parents during the third trimester of pregnancy.

When the children reached 36 months old, scientists evaluated their development using behavioral questionnaires. They then compared developmental outcomes with gut bacteria and epigenetic patterns.

The results showed that several factors were connected with epigenetic patterns at birth. These included delivery method, pregnancy length, having older siblings, and maternal allergies.

However, researchers found that parental gut microbiomes did not appear to influence these birth-related epigenetic changes, as per a report by Science Daily.

What factors shape a baby’s microbiome?

The study found that the infant microbiome develops through several early-life influences. Delivery method, antibiotic exposure, older siblings, and breastfeeding were all linked to the types of bacteria present during the first year.

Babies born through Caesarean section showed different DNA methylation patterns in certain genes related to immune function and brain development.

Scientists also discovered that epigenetic patterns at birth could affect how the gut microbiome changes over time.

Infants with higher DNA methylation levels in specific immune-related genes were more likely to develop less diverse gut microbiomes by 12 months. These genes help the body recognize and respond to harmful organisms.

The findings suggest that early biological signals may help guide the formation of gut bacteria during infancy, as per a report by Science Daily.

Could certain bacteria lower neurodevelopmental risks?

When researchers looked at behavioral outcomes at age three, they found associations between specific combinations of epigenetic markers and gut microbes with signs of ASD and ADHD.

The study also identified bacteria that may provide a protective effect.

Children with epigenetic patterns connected to autism spectrum disorder were less likely to show signs of ASD if they developed Lachnospira pectinoschiza during infancy.

Similarly, children with epigenetic patterns linked to ADHD appeared less likely to show signs of the condition if they acquired Parabacteroides distasonis during their first year.

Senior author and gastroenterologist Francis Ka Leung Chan of The Chinese University of Hong Kong said the discovery could eventually lead to new ways of supporting child development.

“Certain bacteria seem to offer protection, which is exciting because it suggests there could be ways to support a child’s development through diet or probiotics in the future,” Chan said.

Could probiotics support brain health?

Researchers say the findings do not mean a child’s developmental future is decided at birth. Instead, they believe the study reveals only one part of a much larger and more complex picture.

“The foundations for brain health are laid very early, even before birth,” says Tun. “However, we don’t want people to think this means a child’s developmental path is fixed at birth. These are complex conditions with many causes, and we’ve only uncovered a small piece of a very large puzzle.”

The research team is continuing to follow the children involved in the study to better understand how early-life microbiome development and epigenetic patterns influence health later in childhood.

Scientists also believe future research may explore safe interventions involving probiotics or live biotherapeutics.

“The ultimate goal is to develop safe, non-intrusive early interventions such as specific probiotics or live biotherapeutics, that could help nurture a healthy gut microbiome and potentially reduce the risk of neurodevelopmental challenges,” says first author and gastroenterologist Siew Chien Ng of The Chinese University of Hong Kong.

The study was supported by InnoHK, the Government of Hong Kong, the D. H. Chen Foundation, and the New Cornerstone Science Foundation.