Altered amyloid plasma profile in patients with disabling headaches after SARS-CoV-2 infection and vaccination.

BACKGROUND AND OBJECTIVES: Persistent headache has emerged as a symptom following acute COVID-19 and, to a lesser extent, after SARS-CoV-2 vaccination. However, the underlying mechanisms remain poorly understood. This study aimed to evaluate plasma levels of amyloid-related biomarkers in patients experiencing persistent headaches after COVID-19 or SARS-CoV-2 vaccination. METHODS: In this prospective observational cohort, patients presenting with severe headache as the dominating symptom after COVID-19 (n=29) or SARS-CoV-2 vaccination (n=31) had neurological assessments with reassessments after 6 months. Plasma levels of amyloid precursor protein (APP), pregnancy zone protein (PZP), cathepsin L1 (CTSL) and serum Amyloid A (SAA1) were measured using ELISA and compared with levels in healthy controls (n=16). RESULTS: We found a strong and persistent upregulation of APP in patients with headache after COVID-19 as compared with the two other groups. Notably, APP levels remained elevated at both inclusion and after 6 months in individuals with accompanying cognitive symptoms. In contrast, PZP levels were increased in patients with headache after SARS-CoV-2 vaccination at both time points relative to healthy controls. CTSL was only elevated in the post-COVID-19 at baseline, whereas SAA1 showed levels comparable across all groups. CONCLUSION: Altered plasma levels of soluble markers, potentially reflecting changes in amyloid processing, were found in patients with persistent headache following SARS-CoV-2 vaccine, particularly in those with persistent headache after COVID-19. In the latter group, we also found some association with cognitive symptoms. TRIAL REGISTRATION NUMBERS: NCT04576351 and NCT05235776.