Tick-borne infections can trigger bipolar disorder in children, study suggests 

Psychiatrists should recognize the role that infectious diseases play in mental illness and screen their patients for them, says a prominent American researcher in a new paper that outlines a possible link between tick-borne infections and pediatric bipolar disorder.

It’s the latest study in a growing body of data that shows these pathogens can play a role in triggering psychiatric disorders. 

The research outlines a striking discovery: of 37 cases in which children were diagnosed with bipolar disorder, the vast majority had also contracted Lyme disease and other illnesses associated with tick bites, or had shown evidence of exposure to ticks. 

“More than three-quarters of the cohort demonstrated confirmed tick-borne infections,” writes Dr. Rosalie Greenberg in a paper published by the journal Frontiers In Medicine last November.

“Overall, 92 per cent (34/37) had evidence of tick-borne exposure, with 81 per cent (30/37) meeting both laboratory and clinical criteria.”

The patients ranged in age from three to 16 and came from a single private psychiatric practice in New Jersey, a state that’s long been a hot zone for Lyme disease and other illnesses spread by ticks. They all underwent full assessments, including details of their bipolar diagnosis, personal history and family history, including any incidence of bipolar disorder and other psychiatric problems in previous generations. Then, they were tested for exposure to tick-borne infections (TBIs).

Greenberg, a top psychiatrist and independent researcher specializing in pediatric psychiatric disorders, cautions that while the study is “limited by its single-practice retrospective design, these findings suggest that tick-borne pathogens may play a role in the pathogenesis of bipolar symptoms in youth, warranting larger, controlled studies.”

Greenberg says her research also underscores the urgency of finding better methods of testing and treatment for tick-borne illnesses in North America. Over the past several decades, ticks have taken advantage of climate change to spread from the U.S. into the Maritimes and southern regions of Quebec, Ontario, Manitoba and British Columbia. 

And as they’ve expanded their footprint, case counts have soared. In fact, at least one estimate suggests the real number of Lyme disease cases in Canada is more than 13 times higher than the official reported total.

“Basically, the tick bite serves as a dirty needle for the spread of potentially pathogenic materials,” Greenberg writes.

The disease can be difficult to diagnose because current testing methods can be inaccurate and it can mimic the symptoms of other illnesses. If it isn’t caught and treated early, it can lead to debilitating chronic symptoms and even death in rare cases. 

Evidence of impact on mental health 

Bipolar disorder is a chronic mental condition that features wide swings in mood, from bouts of euphoria and manic energy to deep depression, which can lead to thoughts of suicide. The pediatric form of the disease is most common in teens but can also hit younger children. Experts don’t know the exact cause but they believe it’s a combination of genetics, imbalances in brain chemistry and environmental factors. 

Evidence continues to moun that if they’re not treated promptly and effectively, Lyme disease and other TBIs can play a role in triggering bipolar disorder and mental illnesses like it. Greenberg cites research that shows tick-borne infections are linked to “neuropsychiatric and neurocognitive” conditions. 

“Parallel to these developments, a substantial body of research has underscored the critical role of immune dysregulation and inflammatory processes in the pathogenesis of a broad range of psychiatric conditions, including schizophrenia, major depressive disorder, bipolar disorder, anxiety disorders, obsessive-compulsive disorder (OCD), and attention-deficit/hyperactivity disorder (ADHD),” she writes. 

“Some of the strongest evidence has been in the area of mood disorders, both depression and bipolar disorder. A wide array of infectious agents – including bacterial, viral, fungal, and parasitic pathogens – have been implicated as potential initiators of systemic and neuroinflammatory responses.”

So how could TBIs play a role in triggering or worsening mental illnesses like bipolar disorder? Greenberg points to studies that show the bacterium that causes Lyme disease can cross  what’s known as the “blood-brain barrier” – a cellular layer that protects the brain from infectious agents and toxins in our bloodstreams while allowing nutrients and oxygen to pass through. 

“When compromised, pathogens and toxic substances as well as peripheral immune and inflammatory agents … can enter the central nervous system. Their entry can subsequently interfere with neuronal function, create neuroinflammation and change neurotransmission,” she writes.

Greenberg also notes several similarities between bipolar disorder and chronic Lyme. She says both disorders appear to:

• Be multi-systemic illnesses,
• Feature sleep disruption and cognitive dysfunction,
• Be associated with depression, suicidal ideation and increased risk of suicide, 
• Feature immune dysfunction,
• Have symptoms that worsen with stress,
• Respond to some of the same antibiotic and anti-inflammatory agents.

Greenberg says pediatric bipolar disorder is a more common diagnosis in the U. S. – and often has an earlier age of onset – than in Europe, and she suggests a possible cause: the much stronger inflammatory response caused by Borrelia burgdorferi, the bacterial strain that causes Lyme disease in North America, than that caused by European strains. 

She says doctors and psychiatrists should be more aware of the growing evidence that there’s a connection between tick-borne infections and psychiatric disorders, promptly screen patients for these pathogens and treat them as soon as possible.

“Historically, discussion of symptoms caused by infectious diseases has focused on the more obvious physical manifestations rather than the effect on mental processes,” Greenberg writes.

“Recognition that the immune system through mechanisms such as inflammation, immune dysfunction, breakdown of the blood brain barrier, and autoimmunity plays an important role in the development of psychiatric illness and not solely physical disorders, is a rapidly expanding area of scientific study.”