Is it possible for the bacterial community in your gut to actually be related to psychiatric illnesses such as schizophrenia and bipolar disorder? Research on the human microbiome and its effects on health and illness has exploded into the worlds of medicine and research. It is increasingly clear that the microorganisms in the human intestinal tract, and the genes produced by all of those microscopic living things, play critical roles in an individual’s patterns of overall wellness—far beyond helping us digest food effectively.
Microbiota is the ecological community of microorganisms (mostly bacteria, but also fungi, viruses, and so on) that live in a particular location, such as your gut. Microbiome refers collectively to the genes harbored in these microorganisms. Researchers must understand the patterns of both the organisms and the genes to help clarify the roles these microscopic creatures play in the body’s health and function.
A study in the journal Brain, Behavior, Immunology (May 2017), entitled “The microbiome, immunity, and schizophrenia and bipolar disorder,” summarizes some of the current research looking at the microbiome as it relates to schizophrenia and bipolar disorder. The article reports that many studies in animal models have shown that the gut microbiome could affect thinking and behavior through effects on the immune system. Some human studies have shown that people with psychiatric conditions took antibiotics more frequently than people without these disorders. Humans take antibiotics to kill off unwanted bacterial infections, but these medications also kill off some of the microbiota, thus altering the person’s microbiome. The next question then is whether these microbiome changes were related to the development of the psychiatric conditions. This article also points to studies that found different microbiota in the mouths and throats of people with schizophrenia compared to those without.
Babies are born with “sterile” guts; they don’t have any gut microbiota. But in the birth process, microorganisms colonize the baby’s mouth and intestine, starting off their process of building a microbiome that eventually looks like an adult’s. Many researchers are exploring how the developing microbiome might affect the developing brain and nervous system. While it seems clear that there are effects, the exact mediating processes and what exactly gets changed or affected remains very unclear. While the immune system is thought to be one pathway, other mechanisms are also being investigated.
Many other areas of research show promising results when looking at the microbiota, microbiome, and illness. Autism researchers are looking at the “gut-microbiome-brain” connection, and there are strong indicators that the microbiota and microbiome have some relationships to autism. Obesity has been shown to have some very interesting connections to the microbiota in mouse studies. Changing the patterns of bacteria in mouse guts can transform the mouse from obese to lean and vice versa without changing diets. A study from China last month in the World Journal of Gastroenterology reports a case of a 20-year-old with Crohn’s disease and seizures. They treated her with fecal microbiota transplantation—giving her gut the microbiota of a healthy person—and her gastrointestinal symptoms and seizures improved significantly.
The potential benefits to understanding how the microbiota and microbiome interact with the brain and central nervous system could be enormous. Understanding microorganism mechanisms that increase the likelihood of mental illness such as bipolar disorder or neurodevelopmental conditions like autism would make room to build new interventions that target those mechanisms. The research in these areas is still in early stages, and there is much more to understand and do, but this is an intriguing and promising story in the quest to understand and treat disorders of the brain.