A new study presented at the 2nd congress of the European Academy of Neurology (EAN) shows a link between the digestive tract and neurological diseases. This finding reaffirms the significance for the gut-brain axis and demonstrates that the triggers of neurological diseases can stem from the digestive tract.

Laboratory animals that develop and transform without any microorganisms were studied to assess if the gut can influence behavior. Results revealed and best explained by Dr Lepage from the Institut National de la Recherché Agronimique in France state that “Intestinal microbes can verifiably produce neuromediators that have an effect on the brain. Germ free mice showed less anxiety than their conspecifics whose gut was populated with commensal microbiota. However, there is only scant evidence thus far on how this process works in the human brain.”

Dr Lepage also reports that “the gut microbiome can influence the central nervous system, the development of nerve cells and the immune system.” It is through these networks, as well as the vagus nerve and microbial metabolic processes, that the brain and the gut communicate with each other.

Neuroscientist and Professor John F.Cryan from the APC Microbiome Institute in Ireland has also carried out studies examining the brains of germ free mice previously.  He discovered that in one of the regions of the brain, the prefrontal cortex, there was increased myelination as compared to animals that were exposed to normal conditions. This can have direct repercussions for myelin related disorders. Furthermore processes that are dependent on microbiome have comprised of adult hippocampal neurogenesis and microglia activation. In other words, the activation of the brain and marrow cells which are similar to immune cells.

These findings provide us with a new dimension to determine the cause of multiple sclerosis (MS). Multiple sclerosis is a disease of the brain and spinal cord. The myelin sheath that protects the nerve fibers is attacked by the immune system resulting in communication problems between the brain and the body. Dr Gurumoorthy Krishnamurthy, from the Max Plank Institute for Neurobiology in Martinsried in Germany, says that the bacterium that is responsible for triggering MS can actually be useful as it is required for digestive purposes. Studies with genetically modified mice revealed that animals which appeared to have normal intestinal microbiota, and were free of external influences, went on to develop inflammation of the brain. At the same time, those that were kept in a germ free environment continued to be healthy.

This difference is explained by the activation of the immune system with normal intestinal microbiota occurring in two phases. In the first phase, the T cells are activated and then multiplied in the lymphatic vessels of the intestinal tract. They then go on to stimulate B cells to form disease causing antibodies with the help of surface proteins present in the myelin sheath. The myelin sheath is thus destroyed in phases through inflammatory reactions in the brain which are triggered almost in the same manner as MS takes place in humans. This makes it clear to us that a change in the immune system is what actually gives way to MS and further research could provide us with new options for therapy.

The human microbiome is equivalent to the human genome. The genes that are present in our microbiome exceed the number of genes in our genome by about 100 to 1.  They cover a huge part of our body and are responsible for various functions that are beneficial or detrimental to our health and well being. The development of the gut microbiome is dependent on a few important factors such as the microorganisms absorbed at the time of birth from the mother, the food that a person eats, infections, stress and our genetic makeup. The gut microbiota plays a significant role in the breakdown and absorption of nutrients. Without its existence, our body would not be able to get the much needed nutrition it needs and thus will be unable to function.

The Institut National de la Recherché Agronimique (INRA) in France is a public scientific and technical research establishment dedicated to agricultural science under the joint authority of the Ministries of Research and Agriculture. INRA is the first institute that started agricultural research in Europe and second in the entire world.

The APC mircobiome institute in Ireland was founded in 2003 and aims to bring together scientists from all backgrounds to share ideas and resources. Their main focus is on the gastrointestinal bacteria community (the microbiota).

The 2nd congress of the European Academy of Neurology (EAN) is currently taking place in Copenhagen, Denmark from May 28-31, 2016. It is partnered by the Danish Society of Neurology and is a great platform to come and interact with the European network and scientific exchange through lectures, small group teaching courses and exhibitions.