Plasma levels of the neuron damage markers brain-derived tau and glial fibrillary acidic protein in Lyme neuroborreliosis: A longitudinal study

BACKGROUND: A reliable blood biomarker for neuroborreliosis (NB) has yet to be identified. This study investigated levels of neuron damage markers glial fibrillary acidic protein (GFAP) and brain-derived tau (BD-tau) over six months of follow-up in patients with NB. The aim was to evaluate the potential of these biomarkers for monitoring treatment response and prognostic purposes.

METHODS: A retrospective longitudinal cohort study including plasma collected at diagnosis and approximately three- and six-months post diagnosis from adult NB patients enrolled at the Department of Infectious Diseases, Rigshospitalet between 2018 and 2020. BD-tau concentrations were measured in-house using the Single Molecule Array (Simoa) HD-X platform, while GFAP concentrations were assessed on the same platform utilizing the GFAP Discovery Kit. Changes in biomarker concentrations were analyzed using linear mixed models with an unstructured covariance pattern, with follow-up included as a categorical fixed effect.

RESULTS: A total of 23 patients (median age: 63 years; male/female ratio: 16/7) with 56 plasma samples were analyzed; 12 patients had complete samples. GFAP and BD-tau levels showed minimal variation throughout the study period. Patients with persistent symptoms had GFAP concentrations that were 55 % higher at diagnosis compared to those who fully recovered, though this difference was not statistically significant (p = 0.09). No significant associations were observed between biomarker levels and treatment response or long-term outcomes.

CONCLUSIONS: This longitudinal study did not find BD-tau or GFAP to be effective blood biomarkers for monitoring treatment response or predicting outcomes in NB.