Under the Hood

A Future Schizophrenia Test May Examine Throat For Answers; The ‘Intriguing’ Link Between The Stomach And Brain

Gut Bacteria And The Brain
Mental health disorders may be linked to the type of bacteria in a person's gut. Photo courtesy of Shutterstock

Trillions of microbes inhabit the human body, and although their primary role is to help digest food, process vitamins, and stave off infection, their effects may extend beyond the gut and into the brain. Researchers at George Washington University found a link between bacteria in a person’s throat, which comes from their gut, and a schizophrenia diagnosis. The study, published in the journal Peer J, may reveal how the stomach affects a person’s mental state and if there’s a way to intervene before they develop schizophrenia.

"[A schizophrenic’s throat] seems to harbor different proportions of oral bacteria than healthy individuals," said the study’s lead author Eduardo Castro-Nallar, a PhD candidate at GW's Computational Biology Institute, in a press release. "Specifically, our analyses revealed an association between microbes such as lactic-acid bacteria and schizophrenics."

Previous research has linked these microbes to the immune system and mental health. For example, internist Dr. Raphael Kellman, author of the Microbiome Diet, believes the Western diet's effects on the microbiome have resulted in increased rates of depression, anxiety, and other emotional, and cognitive disorders. Schizophrenia is a chronic and life altering brain disorder that causes people to suffer from delusions, according to the National Institute of Mental Health.

Last year, a study published in Molecular Psychiatry, suggested the same, finding that an individual’s microbes “majorly impact... cognitive function and fundamental behavior patterns.” The gut contains a community of microbes unique to each person, and has developed over time into an immensely complex metabolic entity weighing between 2 and 6 pounds, comparable to the weight of the human brain. The gut produces many substances that are key to the nervous system, which connects to the brain.

Schizophrenia affects people throughout the world regardless of racial, ethnic, or economic background, according to the Schizophrenia and Related Disorders Alliance of America. There are approximately 3.5 million people diagnosed with the disorder in the United States, making it one of the leading causes of disability and dependence.

Although the exact cause of schizophrenia is still unknown, discovering there’s a link between lactic-acid bacteria and the disorder may lead to new avenues of research, and eventually discovery. Schizophrenia may be rooted in a gene mutation that’s responsible for making important brain chemicals, ultimately changing the way a person’s hormones and cognitive signals fire and communicate.

Castro-Nallar and his research team need to replicate their findings and expand the participation group before they take any steps toward using a person’s throat bacteria for diagnostic purposes. However, the study’s co-author Keith Crandall, director of the CBI, said: "The results are quite intriguing and suggest potential applications of biomarkers for diagnosis of schizophrenia and important metabolic pathways associated with the disease."

Source: Castro-Nallar E and Crandall K. Composition, Taxonomy and Functional Diversity of the Oropharynx Microbiome in Individuals With Diversity of the Oropharynx Microbiome in Individuals With Schizophrenia and Controls. Peer J. 2015.