The value of serum glial fibrillary acidic protein as a biomarker of astrogliosis in different neurological diseases

Background: Glial Fibrillary Acidic Protein (GFAP) is a well-established biomarker of astrocytes and astrogliosis, a pathological response observed in various neurological diseases. This study aimed to evaluate the diagnostic performance of serum GFAP in Alzheimer's disease (AD), multiple sclerosis (MS), and transthyretin amyloidosis (ATTR) polyneuropathy. Methods: We performed a retrospective observational study, including 498 participants (337 healthy controls and 161 patients with AD, MS, or ATTR amyloidosis). Serum GFAP levels were measured using the Lumipulse G1200 platform, and statistical analyses were performed to compare levels across disease groups and assess their diagnostic accuracy. Results: GFAP levels were significantly elevated in all neurological disease groups compared to age-matched controls, with the highest levels found in AD (79.4 pg/mL vs. 39.5 pg/mL, p = 2.55 × 10−12). ROC curve analysis revealed that GFAP had strong diagnostic performance for AD (AUC = 0.86), moderate performance for ATTR amyloidosis (AUC = 0.67), and poor performance for MS (AUC = 0.61). Conclusions: These findings suggest that GFAP is a promising biomarker for AD, reflecting astrocytic activation and neuroinflammatory processes. Its diagnostic utility in ATTR amyloidosis is moderate, while its role in MS remains limited.