It’s a mystery.

• Why do some people suffer from depression, while others don’t?
• Why do some people suffer from schizophrenia, while others don’t?
• Why do some people who experience trauma suffer from PTSD, while others don’t?

People who are dealing with these problems have asked themselves these questions time and again. What is the difference between the sufferers of these and other mental health disorders, and people who have no such problems? For a long time, medical science has pursued a lot of leads but has come up empty. There are probably multiple factors that enter into the equation, but one that has emerged only recently has come as a big surprise.

What makes us who we are? Many factors, starting at the moment of conception, and carrying on throughout life. At conception we are assigned a genome. The genome is the molecular code sequence that determines the colors of our eyes, skin, and hair. It also says a lot about what diseases we will contract at some point in our lives. At the same time, we are gifted with an epigenome.

The epigenome is a set of switches that determines which of the genes in our genome will be turned on and functioning, and which will be turned off. In your body, there are other “-omes,” including the transcriptome, metabolome,and the proteome. They are all critically important, but the -ome I want to talk about today is the microbiome. A biome is an ensemble of living things. A microbiome is an ensemble of very small living things, including bacteria, archaea, fungi, viruses, and protozoa that inhabit our bodies. We are accustomed to thinking of these things as disease-causing invaders of our bodies. Many are indeed harmful. However, many others have been in a symbiotic relationship with humans for as long as there have been humans.

The greatest concentration of microbes in the human body can be found in the gut, where they perform important functions. They help to digest food, such as cellulose, which we cannot digest by ourselves. They also manufacture molecules that we need, such as vitamin B-12. In addition, they have a role in regulating the immune system, helping to control the “bad” microbes that would cause disease.

You may be surprised to know that when you step on the bathroom scale in the morning, any where from two to six pounds of the weight reading you receive is the weight of your microbial guests. If you have the right mix of microbiota, those guests are working hard to keep you healthy. After all, you are providing them with a comfortable environment, so it is only right that they should reciprocate by keeping your metabolism in balance. Ideally, you will have the most helpful microbes in the optimal proportions. You start to experience problems when you have the wrong microbes or the right microbes in the wrong proportions. In general, the more different microbes, the better. Diversity helps to keep things on an even keel.

How might the composition of the microbiota in a person’s gut affect problems with the brain, such as depression, schizophrenia, PTSD, or other maladies? It turns out, there is a direct connection between the gut and the brain, as well as indirect connections. Gut microbes produce neurotransmitters, such as GABA and serotonin. Both substances can affect mood, appetite, and thinking. They activate the vagus nerve, which goes directly to the brain. The mix of microbes in the gut microbiota can not only affect brain states such as depression and schizophrenia, but also affect susceptibility to obesity by modulating mood and appetite.

“Disease can not only be caused by the presence of the wrong kinds of microbes, but also by the absence of the right kinds.”

There is still some controversy as to whether depression can be laid at the feet of gut microbiota, but the large Flemish Gut Flora Project has found an association between diagnosed clinical depression and low levels of two bacterial families, Coprococcus and Dialister, which normally are present at much higher levels. In another study, a strong association was found between the absence of certain other bacterial families and schizophrenia. That’s an eye opener. Disease can not only be caused by the presence of the wrong kinds of microbes, but also by the absence of the right kinds. A germ-free environment is not necessarily the healthiest environment. Another example of this is that children brought up in homes that include a dog are less likely to have serious allergy problems than are children brought up in homes without pets. Dogs enhance the microbial diversity of the environment. This, in turn, tells the child’s immune system that a wide variety of microbes are normal and nothing to get upset about.

We could be on the threshold of the ability to effectively treat diseases that up until now have remained a mystery. Current research is shining a light into the dark recesses of parts of our body where we never guessed we had guests, guests that could have a profound effect on our well-being. It pays to keep up to date on advances in the study of the interactions between people and the fellow travelers that they carry.

Bio:

Allen G. Taylor is a 30-year veteran of the computer industry and the author of over 30 books, including Develop Microsoft HoloLens Apps Now, Get Fit with Apple Watch, Cruise for Free, SQL For Dummies, 8th Edition, Crystal Reports 2008 For Dummies, Database Development For Dummies, Access Power Programming with VBA, and SQL All-In-One For Dummies, Second Edition. He lectures internationally on astronomy, databases, innovation, and entrepreneurship. He also teaches database development and Crystal Reports through a leading online education provider. For the latest news on Allen’s activities, check out his blog at www.allengtaylor.com or contact him at allen.taylor@ieee.org.