An imbalanced gut microbiota in early childhood is linked to conditions like autism and ADHD later in life, as per a study conducted by scientists from the University of Florida and Linköping University, detailed in the journal Cell.
This study represents the first prospective investigation into the composition of gut flora and various other factors in infants, as they relate to the development of the children’s nervous system. Researchers have identified numerous biological indicators that appear to be linked to future neurodevelopmental disorders, including autism spectrum disorder, ADHD, communication disorders, and intellectual disabilities.
Eric W. Triplett, a professor at the Department of Microbiology and Cell Science at the University of Florida, U.S., and one of the study’s lead researchers, highlights the remarkable aspect of the findings: these biomarkers are detectable at birth in cord blood or in the child’s stool at one year of age, more than a decade before diagnosis.
The research is part of the ABIS (All Babies in Southeast Sweden) study, spearheaded by Johnny Ludvigsson at Linköping University. This longitudinal study has tracked over 16,000 children born between 1997 and 1999, representing a diverse cross-section of the population, from birth through their twenties. Among these individuals, 1,197 children, equivalent to 7.3%, have received diagnoses of autism spectrum disorder, ADHD, communication disorders, or intellectual disabilities.
Through comprehensive surveys conducted at various stages of the children’s upbringing, numerous lifestyle and environmental factors have been identified. Additionally, for a subset of participants, researchers have analyzed substances present in umbilical cord blood and the composition of bacteria in their stool when they were one year old.
“We observe distinct variations in the gut microbiota during infancy between those who later develop autism or ADHD and those who do not,” explains Ludvigsson, senior professor at Linköping University’s Department of Biomedical and Clinical Sciences, who co-led the study with Triplett. “We’ve identified correlations with certain factors influencing gut bacteria, such as antibiotic use in the child’s first year, which appears to elevate the risk of these conditions.”
Moreover, children experiencing recurrent ear infections within their initial year face an elevated likelihood of receiving a diagnosis of developmental neurological disorders later in life. While the infection itself may not be the direct cause, researchers suspect a connection to antibiotic therapy. Specifically, they observed that the presence of Citrobacter bacteria or the absence of Coprococcus bacteria heightened the risk of future diagnoses.
One potential explanation could be that antibiotic treatment disrupts the balance of gut flora, contributing to the development of neurodevelopmental disorders. Previous research has shown that antibiotic treatment poses a risk of altering gut flora and increasing the likelihood of immune-related diseases, such as type 1 diabetes and childhood rheumatism.
“Certain bacteria like Coprococcus and Akkermansia muciniphila may have protective effects,” explains Angelica Ahrens, Assistant Scientist in Triplett’s research group at the University of Florida and the lead author of the study. “These bacteria were associated with key substances in stool samples, including vitamin B and neurotransmitter precursors that play crucial roles in brain signaling. Overall, we observed deficiencies in these bacteria among children later diagnosed with developmental neurological disorders.”
Additionally, the study reaffirms that parental smoking increases the risk of developmental neurological disorders in children, while breastfeeding appears to offer protective benefits.
In cord blood samples collected at birth, researchers analyzed various metabolic substances such as fatty acids and amino acids. They also measured harmful external substances like nicotine and environmental toxins. By comparing the levels of these substances in the cord blood of 27 children diagnosed with autism to those without a diagnosis, the researchers aimed to identify potential biomarkers.
It was discovered that children later diagnosed with developmental neurological disorders exhibited low levels of several crucial fats in their umbilical cord blood. One of these fats was linolenic acid, essential for synthesizing anti-inflammatory omega-3 fatty acids, which play diverse roles in brain function.
Moreover, the same group showed higher levels of a PFAS substance compared to the control group. PFAS substances, utilized as flame retardants, have been linked to adverse effects on the immune system and can enter the body through various routes such as drinking water, food, and inhalation.
While the findings from the Swedish children may not directly apply to other populations, it is imperative to investigate these issues in diverse groups. Additionally, the researchers pondered whether gut flora imbalance acts as a trigger or is a consequence of underlying factors like diet or antibiotic use.
Despite adjusting for potential risk factors impacting gut flora, the association between future diagnosis and many bacteria persisted, suggesting that certain differences in gut flora are not solely attributable to these risk factors.
Although the research is still in its infancy, the revelation that numerous biomarkers for future developmental neurological disorders manifest early in life raises the prospect of developing screening protocols and preventive interventions in the future.
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