Early Antibiotic Use in Infants May Lead to Long-Term Behavioral Changes, Study Suggests

Jerusalem, 23 September, 2024 (TPS) -- The overuse or early use of antibiotics in children may have unintended behavioral effects later in life, findings by Israeli researchers suggest.

Scientists at Bar-Ilan University in Ramat Gan revealed a significant connection between early disruptions in the gut microbiome and persistent aggressive behaviors in mice. The gut microbiome refers to the diverse community of microorganisms — primarily bacteria, but also viruses, fungi, and other microbes — that reside in the digestive tract, particularly the intestines. These microbes play a crucial role in maintaining health and influencing various physiological processes in the body.

The research, led by Prof. Omry Koren and graduate student Atara Uzan-Yuzari highlighted how alterations in the microbiome, particularly due to antibiotic exposure during critical developmental periods, can lead to increased aggression later in life.

Recently published in the peer-reviewed Brain, Behavior, and Immunity journal, the study builds on previous work that showed a similar link between antibiotic use and aggressive behavior in fruit flies. This time, the researchers utilized a mouse model to investigate how microbiome disruption affects behavior, biochemistry, and neurological functions.

One of the key elements of the study involved transplanting microbiomes from infants who had been treated with antibiotics shortly after birth into the mice. The results were striking — the “humanized” mice exhibited significantly more aggressive behavior compared to mice who received microbiomes from antibiotic-free infants.

“Our findings are revolutionary,” said Koren. “They suggest that a disrupted microbiome during critical developmental periods can lead to persistent aggressive behaviors later in life.”

The team employed the “resident-intruder” paradigm to measure aggression, introducing a foreign mouse into the home cage of a resident mouse. The mice with reduced gut bacterial diversity, caused by early-life antibiotic treatments, consistently showed higher levels of aggression.

The researchers believe that early-life antibiotic exposure in humans may similarly impact long-term social behavior, offering fresh insights into the gut-brain axis. The gut-brain axis is the communication network connecting the gastrointestinal tract and the brain. This complex system involves multiple pathways, including neural, hormonal, and immune signaling, which allow the gut and the brain to influence each other’s functions.

Biochemically, the team measured neurotransmitter levels such as serotonin and tryptophan in the brains of the mice. They identified patterns of gene expression linked to aggression, particularly in the septum, a brain region known to regulate aggressive behavior. This biochemical analysis further cemented the connection between microbiome health and behavioral outcomes.

The study indicates that early or excessive use of antibiotics could lead to unintended behavioral effects. This could prompt healthcare providers to adjust antibiotic prescriptions for infants to protect the developing gut microbiome. Probiotic supplements may also be introduced for infants undergoing antibiotic treatment to help restore gut bacterial diversity and reduce the risk of future behavioral issues like aggression.

The research opens the door to the development of drugs designed to influence the gut-brain axis, targeting specific gut bacteria or their metabolites to modulate behavior. Pharmaceutical companies could potentially focus on gut health as a way to treat aggression or even social disorders such as autism or ADHD.

Pediatricians screening infants for microbiome disruptions could offer early interventions to improve long-term behavioral outcomes, potentially reducing aggression and related issues in later childhood and adolescence. To mitigate future behavioral challenges in their children, parents might receive guidance on nutrition while reducing unnecessary antibiotic use.