Johns Hopkins Medicine researchers report using an advanced form of brain scan to show 12 patients with documented post treatment Lyme disease syndrome had elevated levels of a chemical marker of widespread brain inflammation compared to 19 controls, as published in the Journal of Neuroinflammation.
Lyme disease is diagnosed in an estimated 300,000 Americans each year, it is a bacterial infection transmitted through tick bites, infections can be treated with antibiotics. PTLDS is often diagnosed if patients report brain fog and fatigue for at least 6 months after treatment. While little is known about what causes PTLDS studies have shown those with it have elevated markers of inflammation such as CCL19 in the bloodstream, but it has not been clear where the inflammation may be occurring.
Positron emission tomography imaging technique was optimized in which specially labeled molecules or radiotracers bind to translocator proteins. TSPO is released by microglia and astrocytes brain immune cells, levels of TSPO are higher when brain inflammation is present. Ths team said this type of PET scan can visualize TSPO levels, astrocyte, and microglia activation throughout the brain.
Pet scans from 12 patients diagnosed with PTLDS were compared to 19 controls; PTLDS participants all had history of confirmed or probable Lyme disease infections, and documented evidence of treatment with no history of depression diagnosis, that all reported presence of fatigue and had at least one cognitive deficit such as concentration or memory issues. Control were adult men and women aged 18+ and did not differ in age of BMI.
Scans revealed across 8 different brain regions participants with PTLDS had significantly higher levels of TSPO; overall when brain regions were combined and data adjusted for BMI, age, genotype, and brain region the mean difference was 0.58 TSPO levels between the PTLDS patients and the controls.
The team notes the study was small and whether or not results apply to all with post treatment Lyme disease syndrome must be verified in larger and broader studies. This study did not include patients who recovered from Lyme disease but did not develop PTLDS.
According to the team the study provides evidence of brain fog in patients with PTLDS having a physiological basis and is not just psychosomatic or related to anxiety or depression; and suggest drugs designed to curb neuroinflammation may be able to treat PTLDS but require trials to determine safety and benefit. Variations of PET scans in the future may be able to help narrow down more specifically which subsets of microglia and astrocytes are activated helping to guide drug development further.
