By Pat Anson, PNN Editor

Researchers at Johns Hopkins University have documented changes in the brains of patients with post-treatment Lyme disease that may explain symptoms such as brain fog, memory loss and other cognitive issues. The finding could also have implications for patients with long covid, fibromyalgia, multiple sclerosis, chronic fatigue and other health conditions who have cognitive problems.    

Lyme disease is a bacterial illness spread by ticks that causes a rash, flu-like aches and fever, joint pain and fatigue. Most patients fully recover when treated early with antibiotics, but up to 20% of those with post-treatment Lyme disease (PTLD) have long-term symptoms, including depression, insomnia and cognitive difficulties. There is usually no clinical or laboratory evidence to explain their ongoing issues.

“Objective biologic measures of post-treatment Lyme symptoms typically can’t be identified using regular MRIs, CT scans, or blood tests,” says John Aucott, MD., director of the Johns Hopkins Lyme Disease Clinical Research Center.

Aucott and his colleagues recruited 12 PTLD patients and 18 people without a history of Lyme to undergo functional MRI (fMRI) scans while performing a short-term memory task. The scans allow investigators to track blood flow and other changes in the brain in real time.

Their findings, published in the journal PLOS ONE, suggest that cognitive difficulties in PTLD patients are linked to functional and structural changes in the “white matter” of the brain, which is crucial for processing and relaying information. The imaging tests revealed unusual activity in the frontal lobe, an area of the brain responsible for memory recall and concentration. Patients with post-treatment Lyme needed longer periods of time to complete the memory task.

“We saw certain areas in the frontal lobe under-activating and others that were over-activating, which was somewhat expected,” said lead author Cherie Marvel, PhD, an associate professor of neurology at Johns Hopkins.

“However, we didn’t see this same white matter activity in the group without post-treatment Lyme.”

To confirm their finding, researchers used another form of imaging called diffusion tensor imaging (DTI) on all 12 patients with Lyme and 12 of the non-Lyme participants. DTI detects the direction of water movement within brain tissue. Water was diffusing, or leaking, in the the same white matter regions identified in the fMRI.

Researchers believe the increased activity they saw in white matter may reflect an immune system response in the PTLD patients, which may also explain cognitive issues in patients with other chronic health conditions.

“Results reported here may have implications for other diseases in which white matter pathology has been demonstrated (e.g., multiple sclerosis) or in illnesses in which cognitive complaints follow disease onset,” researchers said. “The use of multimodal neuroimaging methods, like the ones used in the current study, may be a viable approach for obtaining information on brain function and structure to identify biomarkers of disease burden.”

Researchers say larger studies with more patients will be needed to confirm their findings, as well as long-term tracking of brain changes from the initial Lyme infection through development of PTLD.

Nearly 500,000 people are believed to get Lyme disease each year in the United States. Diagnoses of Lyme have soared over the past 15 years, according to a recent analysis of insurance claims that found Lyme cases rose 357% in rural areas and 65% in urban areas. The highest rates of Lyme were in New Jersey, Vermont, Maine, Rhode Island and Connecticut.