Mind-altering microbes

“Sorry I’m feeling a bit down today, my bacteria are acting up,” – a sentence you’ve probably never heard, but may do some day as scientists find a link between the microbial colonies in your gut and your mental wellbeing.

The human body is home to a vast network of cells, many of those not being human, but bacterial, protozoal, and viral. The particular gastrointestinal microbes are referred to as the gut microbiota and are completely unique to you. Each person’s gut is colonised from the point of birth and is moulded to be fully mature by approximately the age of three.

It has been known for years that particular diets are associated with particular gut microbiota compositions, and by association, particular conditions including obesity and diabetes, but a controversial concept is emerging that the gut microbiome is also linked to your mental health. In particular, different compositions of gut microbiomes can be associated with various conditions, including depression, autism, and neurodegenerative diseases.

The particular gastrointestinal microbes are referred to as the gut microbiota and are completely unique to you

Studies over the years have related specially-raised “germ-free” mice, absent of any gastrointestinal bacteria, with higher stress responses compared to mice of the same species, but with a fully mature gut microbiome. Not only can changes in the behaviour and hormone-levels of germ-free mice be seen, but also in the physical structuring and wiring of their brains. Studies in animals that are genetically predisposed to develop Parkinson’s show that particular gut microbiomes were required for the disease to emerge and others can increase the progression.

Of course, in reality, no one is completely sterile, and so how can we achieve the healthiest gut possible to ensure the greatest possible chance of good mental health? A general rule is that a healthy microbiome is diverse, and so a well-rounded, varied diet is a great start to remedying your gut back to health.

Not only can changes in the behaviour and hormone-levels of germ-free mice be seen, but also in the physical structuring and wiring of their brains

Studies such as these have kick-started a whole new wave of thought in the approach to mental health, and consequently developed methods by which mental illness could one day be treated. Groups of researchers believe they are on the brink of a medical breakthrough whereby “psychobiotics” can be used to improve mental health.

But how can our behaviours and emotions be affected by these invisible populations in the stomach? Scientists have suggested that one route may be the Vagus nerve – the information superhighway connecting the brain with the gut. There has also been emerging evidence of these bacteria could be hacking into cells by release of tiny strips of genetic information known as microRNAs, which can affect how DNA functions in cells, consequently changing the biochemistry in our brains.

There has also been emerging evidence of these bacteria could be hacking into cells by release of tiny strips of genetic information known as microRNAs

Though the gut microbiome composition is not the sole cause of mental illnesses, which are very complex in nature, and although psychobiotics is not the miracle cure to mental illness we all wish it could be, it is a fascinating prospect for neuroscientists and microbiologists. The microbiome is opening up an entirely new way of approaching medicine and one day we may have another way in which we treat mental illness.