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Early exposure to antibiotics can impair neurological development

Scientists have found that giving antibiotic therapies to infants early in life could alter the parts of the human brain responsible for emotional functions. 

Exposing newborns to antibiotics can have detrimental and irreversible health implications in the long run. Antibiotics can disrupt the development of the gut microbiome which in turn can negatively impact metabolism, immunity and neurological health. Early antibiotic consumption can lead to issues such as obesity, asthma, allergic rhinitis, attention/deficit hyperactivity disorder or ADHD,  autism and other neurological disorders. The type, the dosage prescribed, the duration of treatment and sometimes even prenatal exposure to antibiotics can influence the gut microbiome of the foetus.

The bacterial microbiome in our gastrointestinal tract is heavily determined by the type of diet we are exposed to since infancy. The development and growth of this bacterial population begin at birth and is fostered through social interaction, diet, and environmental factors. Any kind of disturbance to this bacterial population such as Cesarean section delivery, formula feeding, and pre-and postnatal antibiotic exposure can negatively impact and therefore, may compromise childhood health. 

Newborns are highly susceptible to a host of bacterial infections and to treat most of these disorders antibiotics are prescribed with the most common ones being penicillin, cephalosporin, ampicillin and amoxicillin. Antibiotics work to get rid of any kind of bacterial infection in the body and are highly effective and affordable. However extended exposure of antibiotics can make bacteria resistant to them due to the high mutation rates. Hence not only affecting the health but also making the child more vulnerable to infections later on. 

A research team from Rutgers University conducted a study where they found out how early exposure to antibiotics can cause several neurological developmental problems. The laboratory study, published in the journal iScience, suggests that penicillin alters the microbiome and the gene expression of a key protein in parts of the developing brain associated with emotional and cognitive function. These proteins also allow cells to adapt to their changing environment. The findings suggest using alternatives and reducing the use of antibiotics as and when possible to prevent neurodevelopmental problems. 

In the study, the mice were exposed to a low dose of penicillin in utero and some mice were given the antibiotic immediately after birth. The intestinal microbiota composition of these mice was significantly disrupted and gene expression was altered in the frontal cortex and amygdala, two key areas in the brain responsible for the development of memory as well as fear and stress responses. They hypothesized that because antibiotics alter the microbiome composition, it affects the gut-brain axis, leading to issues like ADHD, autism, and learning disabilities. 

Another study conducted by the scientists at the University of Oxford found out that exposing mice to antibiotics from a young age can disrupt their “social” brain. Certain neurotransmitters like vasopressin, oxytocin and endorphins help to boost our moods and enable us to socialise with others. The scientists observed that the expression of the receptors for these chemicals is lower in mice that were exposed to high doses of antibiotics. Since the signalling pathways of vasopressin, oxytocin and endorphins were reduced, it could explain the behavioural deficits seen in antibiotic-treated animals.

This study also went on to explore how disrupting the intestinal microbiome can affect the endorphin system in the brain. This can, in turn, affect the opioid receptors responsible for regulating pain and explain why early exposure to antibiotics can lead to low pain tolerance and cause depression. The study highlights the need to consider the use of antibiotics and how these models of microbiome manipulation can help to understand the effects of various microbes on the brain and behaviour. 

These studies indicate a strong association between antibiotic use in infancy and early childhood on child growth and it is dependent on the age at which the exposure occurs. The impact of neonatal antibiotic exposure on long-term health warrants detailed study with both epidemiological and experimental approaches. In the clinical setting, rapid means of accurately identifying neonates with bacterial infection are needed to limit antibiotic use in these vulnerable subjects.

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