Microbes & Mental Health: A historical review of 400+ journal articles

It’s long been recognized that infectious diseases can play a role in driving mental illness, but gathering evidence to support patient diagnoses can be time-consuming. To help healthcare providers quickly evaluate root-cause triggers, three medical experts — two in psychiatry and one in infectious disease — have reviewed, categorized, and cited hundreds of peer-reviewed journal articles that link specific microbes to common mental illnesses. The authors believe this is the first comprehensive review of associations between microbes and mental illness published in almost 30 years, and it is now available in the December issue of Healthcare.

“If we can catch these drivers of mental illness early in the disease process, many of the most serious cases can be prevented — before the afflicted end up in psychiatric hospitals, unhoused, or incarcerated,” said first author Robert C. Bransfield, MD, a Clinical Associate Professor at Rutgers-Robert Wood Johnson Medical School.

Bransfield and his coauthors, Charlotte Mao, MD, who serves as Invisible’s Curriculum Director and is a pediatric infectious disease physician trained at Harvard Medical School and Boston Children’s Hospital, and Rosalie Greenberg, MD, an adult/child/adolescent psychiatrist trained at Columbia University, spent over a year and a half gathering and evaluating hundreds of peer-reviewed journal articles, then organizing them in two quick-reference tables.

The authors believe that the link between microbes and mental illness can sometimes be missed because of the educational narrowing that happens when medical students transition to specialty fields.

“Psychiatrists end up with limited knowledge of infectious diseases and infectious disease specialists don’t get much exposure to psychiatric diseases,” said Mao. “To facilitate medical specialty collaboration, our article provides potential mechanistic explanations for how microbes might be associated with mental illness and a quick reference to relevant peer-reviewed studies, case reports, and case series.”

The authors began their research with a search of the medical literature for the five mental illnesses with the greatest psychiatric disability — autism spectrum disorders, schizophrenia, bipolar disorders, depressive disorders, and anxiety disorders. It also covered two behaviors of particular concern to both patients and physicians — suicidality and violent behavior. They also conducted a focused review of five infectious diseases commonly associated with mental illness: syphilis; toxoplasmosis; COVID-19; Lyme borreliosis; and group A streptococcal infections, which can cause Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) or Pediatric Acute-onset Neuropsychiatric Syndrome (PANS).

Greenberg, who practices psychiatry in the New York Metropolitan area, sees a lot of mentally disturbed children with undiagnosed chronic Lyme borreliosis or the sequelae of undiagnosed strep infections, conditions that could be prevented with earlier diagnosis and proper treatment.

“What I often say to parents is, trust your instincts if you see abrupt personality changes in your child — things like obsessive-compulsive behaviors or unusual rages. It could be triggered by an infectious disease,” said Greenberg.

To read this open-source article, go here. For free medical education courses on diagnosing and treating microbe-driven mental health conditions such as Lyme neuroborreliosis or bartonellosis, visit the Invisible Education Initiative website, funded by the Montecalvo Foundation.