Photo Source: Neuroscience News
A Silent Threat to Mental Health
By Saanvi Mazumdar, Staff Writer
We all know the feeling of a lingering cough or a sudden fever creeping onto us. Our first instinct is always to find a quick fix, maybe a trip to the doctor, in hopes of a prescription that promises a speedy recovery — talk about instant gratification. The most trusted remedy and the easiest solution to any illness: antibiotics.
Can we even imagine a life without antibiotics? They are our go-to solution for even the mildest sicknesses. But what happens when our saviours become a threat to our bodies?
Nowadays, antibiotic resistance has become one of the most prevalent discussions in the healthcare industry. It refers to a phenomenon where infectious bacteria “develop defenses against the antibiotics” formulated to destroy them. Once such resistance evolves towards one type of antibiotic, other antibiotics also start becoming less effective towards the bacterial infection.
This sheds light on one of the most pressing issues in the healthcare industry — the overprescription of antibiotics. A study conducted in the Canadian primary care setting showed that the rate of unnecessary prescription of antibiotics was 15.4%, including prescription antibiotics for non-bacterial infections like “common cold, acute bronchitis, acute sinusitis and miscellaneous” diseases. Antibiotic resistance is a growing concern for a potential global health crisis, as it can lead to prolonged illness and increased healthcare costs.
However, with all the discourse about the creation of ‘superbugs’, another consequence of antibiotics has been completely overlooked. Antibiotics can directly decline the health of the human gut microbiome, which inadvertently influences the gut-brain axis— the primary communication network between the gut and the central nervous system regulating moods, cognition and emotional wellbeing. So, how do we even find a link between using antibiotics and not just gut health but also the brain?
The human digestive tract is an ecosystem for a variety of microorganisms and contains the largest concentration of bacteria in our body. The gut microbiota is known to house over thousand different bacterial strains. Some researchers even claim that there is approximately a ratio of 1 microbe for each human cell. The bacteria present in our gut have a variety of functions, including the fermentation of food, preventing the spread of pathogens, producing essential vitamins and triggering an immune response.
The gut also produces neurotransmitters like serotonin, dopamine and acetylcholine, which are vital chemicals for mood regulation and cognitive development. This makes it very important for a healthy individual to maintain the harmony of the gut equilibrium. A slight disruption can lead to significant consequences. Even though differences in microbiota composition are mostly due to heredity, several environmental factors, such as “diet, drugs and anthropometric measures,” also play a critical role in its formation.
Antibiotics behave as a ‘double-edged sword’ in regards to the bacterial cells in our body. Considering the fact that the majority of the gut microbiome consists of bacteria, it is highly likely that antibiotics indiscriminately target not only pathogenic bacteria, but also the ones lining our digestive tract.
Research conducted on healthy patients using antibiotics showed how microbial composition continued changing for up to 12 weeks after the prescribed dose of antibiotics ended. In addition, any significant disruptions made to the bacterial population persisted for at least two years after the treatment was completed. Moreover, the overprescription of antibiotics, especially for ailments not caused by bacterial infections, can direct the wrath of these pharmaceutical drugs towards the microbiota, wreaking havoc on their delicate balance.
It might not be obvious, but our brain and our gut are connected through an invisible string. The microbes in the gut directly communicate with the brain through numerous pathways. One such example is the vagus nerve—one of the longest nerves in our body significant for linking the brain and several other internal organs. It is known now that this nerve conveys signals from the brain to the gut and then back to the brain from the gut microbes.
As such, gut bacteria regulate brain function by producing certain metabolites and neurotransmitters, such as dopamine and serotonin, that can readily travel through the vagus nerve and other pathways. It was found that in humans synthesis of over “50% of dopamine” occurs in the gut. The chemical itself is quite crucial for our mental well-being as it modulates the regulation of mood and cognitive abilities. Similarly, serotonin, synthesized by the gut bacteria, plays a role in carrying signals between the nerves and helps in controlling mood and increasing concentration. This provokes the idea that alteration in the gut microbiota may directly or indirectly impact brain function, thereby affecting mental health.
With the increase in awareness about mental well-being, new research has also developed in understanding factors contributing to neurological functions. In doing so, there has been evidence indicating how the gut microbiota impacts neurocognitive processes.
Several psychiatric diseases, such as anxiety and depression, are being associated with antibiotic instigated disruption in the microbial equilibrium of the gastrointestinal system. Recently, it was discovered that patients diagnosed with anxiety and/or depression had immensely low levels of microbial diversity.
Although research is still ongoing to thoroughly understand this complex system in which antibiotics can affect the gut-brain axis, it is still reasonable to theorize that antibiotics usage may influence the risk of developing depression and anxiety, by affecting the production of neurotransmitters in the digestive tract. This is further heightened when several antibiotics are prescribed together in a short time.
There is a significant lack of discourse and very limited research when it comes to investigating the various side effects of antibiotics, other than antibiotic resistance. Specifically, the link between antibiotics and the gut-brain axis is often overlooked, despite its significance.
With the ongoing discussions focusing on mental well-being, it is even more important to find a holistic understanding of how each aspect of our brain can be affected by other aspects, especially in the wake of antibiotics and other potent pharmaceutical drugs.
