Commentary: How microbes may shape mental health and society

“Encephalopathy is defined as an altered mental state due to a medical disorder,” Bransfield explains, noting that certain pathogens — bacterial, viral, and parasitic — can cause immune effects upon the brain. These immune effects include brain inflammation and autoimmunity that may disrupts mood, memory, and behavior. He focuses particularly on Borrelia burgdorferi, the bacterium associated with Lyme disease, and its role in neuropsychiatric symptoms possibly ranging from brain fog to aggression.

What may surprise many is this phenomenon isn’t new. Syphilis, a spirochete caused by Treponema pallidum, is a distant cousin of the Lyme bacterium (Borrelia burgdorferi), which is also a spirochete. These pernicious pathogens are shaped like corkscrews and can literally burrow through the blood-brain barrier or can have immune mediated effects upon the brain even without being in the brain. In its late stages, syphilis often caused terrifying psychotic symptoms and dementia — until penicillin treatment nearly eradicated the disease. When Borrelia burgdorferi isn’t properly treated, especially in the early stages, it can impair the central nervous system and lead to neuroborreliosis or Lyme encephalopathy. This may lead to a range of neurological and cognitive impairments, with some similarities to neurosyphilis.

Symptoms can include brain fog, memory issues, mood disturbances, sleep disruption, neuropathic pain, and cranial nerve palsies.

The parallels are striking, especially their ability to become stealthy, persistent pathogens that can deeply impact mental and neurological health.

Today, a new generation is witnessing similar effects from modern infections — most notably, COVID-19. “Long COVID,” which affects millions worldwide, and has been linked to persistent neuroinflammation, with symptoms such as anxiety, depression, and cognitive impairments. This virus, like the pathogens Bransfield examines, shows how infections, and immune responses to infection, can have lasting effects on the brain.

Importantly, Bransfield acknowledges that infections are not acting in isolation. Environmental toxins, poor diet, chronic stress, non-restorative sleep, and sedentary lifestyles can all worsen neuroinflammation. These factors may amplify symptoms or prolong recovery, especially in individuals with underlying infections.

In other words, a toxic environment — both inside and outside the body — can turn a manageable infection into a psychiatric impairment.

Bransfield cites a growing body of research linking infections like Toxoplasma gondii and HIV with increased risks of psychiatric illness and impulsive behavior.

“There is increasing evidence associating infectious diseases with mental impairments and increased violent behavior,” he emphasizes. This is not just a matter of individual suffering — it has implications for public safety and global stability.

As the science of brain-immune interaction evolves, Bransfield calls for a new medical paradigm, one that bridges psychiatry, neurology, immunology, and infectious disease.

“We must acknowledge that brain health can be altered by pathogens,” he urges, “and that failing to recognize this connection risks both misdiagnosis and missed opportunities for treatment.”

The takeaway? Infections don’t just harm the body — they can hijack the mind. And recognizing this may be key to treating not only hidden illnesses but also healing fractured societies.

Editor’s Note: Always consult your doctor for treatment and testing.

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Mary Jane Heppe has been a national advocate and educator on Lyme disease since 2006.

“This article is dedicated to my beloved son, Vaughan Heppe, who took his life in 2017 as a result of infection-associated mental disorders,” she writes.