Summary: Lyme disease can be treated with long antibiotic courses, but some people develop post-treatment Lyme disease (PTLD). A new study found that PTLD comes from changes in the white matter of the frontal lobe, the front part of the brain. PTLD is a poorly understood condition. It causes body aches, fatigue, sleep problems, trouble thinking and more. Each year, about half a million people get Lyme disease. It is a bacterial infection spread by a tick bite.
Researchers at Johns Hopkins University found that chronic or post-treatment Lyme disease may cause some lasting brain changes. This may explain why some people with chronic Lyme disease still have poor memory, brain fog and other thinking problems. Researchers think these brain changes could also help explain brain problems after COVID, and in multiple sclerosis, fibromyalgia, chronic fatigue syndrome and other illnesses that affect thinking. So we need well-tailored Lyme disease prevention and chronic pain treatment.
Lyme disease is a bacterial infection spread by a tick bite. Early signs include a rash, fatigue, body aches, fever and other flu-like symptoms. Since it is a bacterial infection, antibiotics treat it with great success.
But in many cases, Lyme disease goes undiagnosed, because it is hard to diagnose. Often it is found fairly late. In many cases, antibiotics may wipe out the infection but fail to bring full relief.
Lyme disease seems to cause some lasting brain changes in about 20% of cases. That is significant. These 20% of people develop chronic Lyme disease, also called post-treatment Lyme disease (PTLD). PTLD causes vague symptoms like trouble thinking, depression, fatigue, body aches, poor sleep and more. But in most cases of PTLD, lab tests look fairly normal. So science has struggled to explain what causes PTLD. That makes it one of the hard-to-treat conditions.
In the new study, researchers scanned the brains of people with PTLD. They enrolled 12 patients and 12 healthy people to compare. They used functional MRI (fMRI), which shows how active different brain areas are. It also shows blood flow to different brain parts in real time.
The researchers published their findings in the journal PLOS ONE. They found that many thinking problems in people with PTLD come from changes in the brain’s white matter. These changes slow how information is processed and moved. The study also found significant changes in activity in the frontal lobe, a brain area tied to memory and recall. That was expected, since people with PTLD take longer to recall things and have memory problems.
But when researchers compared these scans with scans of people without Lyme disease, those people showed no unusual activity in the frontal lobe.
The researchers wanted to confirm their findings. So they used another kind of brain scan, called diffusion tensor imaging (DTI), in people with and without PTLD. Again, they found significantly more water movement within brain tissue in people with PTLD. So this test also confirmed unusual activity in the frontal lobe in people with PTLD.
Researchers think this extra brain activity came from a more active immune system in the white matter of that part of the brain. This may explain why people with PTLD have trouble thinking.
These findings matter in many ways. Poorly understood thinking problems like these show up in many other disorders, like fibromyalgia and multiple sclerosis. So researchers say similar tests can be done in patients with those disorders too. The study could help create reliable markers (biomarkers) for these conditions.
Finally, CDC figures show that each year about half a million people suffer from the effects of Lyme disease in the US, and these numbers are rising. So in the last few decades, PTLD cases have multiplied. Yet even with this rise, no reliable test can diagnose PTLD. So this research could help create reliable tests for the condition. It could also help improve chronic pain treatment.
Frequently asked questions
How does Lyme disease affect the brain?
In people who develop post-treatment Lyme disease, brain scans show changes in the white matter of the frontal lobe. That area is tied to memory and recall. Those changes slow how information is processed and moved. That fits the memory trouble and long recall times these patients report. Researchers think a more active immune system in that white matter is driving it.
What are the symptoms of post-treatment Lyme disease?
Post-treatment Lyme disease, also called chronic Lyme disease, causes vague symptoms that linger after antibiotics. These include poor memory, brain fog and other thinking problems, depression, fatigue, body aches and poor sleep. It develops in about 20% of people with Lyme disease. The symptoms are real, even though routine lab tests often come back fairly normal.
Does brain fog from Lyme disease go away?
Not always. Antibiotics treat the infection with great success, but in some cases they fail to bring full relief. Researchers at Johns Hopkins University found that chronic Lyme disease may cause some lasting brain changes. That may explain why some people still have poor memory, brain fog and other thinking problems after treatment.
Why is chronic Lyme disease so hard to diagnose?
Because the usual tests look normal. Lyme disease itself is often found late. And in most cases of post-treatment Lyme disease, lab tests look fairly normal. There is still no test that diagnoses it reliably. The brain scan findings from functional MRI and diffusion tensor imaging may help researchers build reliable markers and tests.
Dr. Gurpreet Singh Padda, MD, MBA, MHP
