Background Patients with relapsing–remitting multiple sclerosis (RRMS) experience fatigue and impaired information processing speed (IPS) frequently, even in the absence of clinical or radiological disease activity. Previous studies investigating associations between fatigue, IPS, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) have reported conflicting results. Objective To examine potential associations between GFAP and NfL with fatigue and IPS in patients with RRMS treated with rituximab (RTX) or natalizumab (NTZ). Methods In this Swedish multicentre cross‐sectional study, we measured plasma GFAP and NfL levels using Simoa Neurology 2‐PLEX B Kit in 121 clinically stable patients with RRMS treated with either RTX or NTZ for at least 24 months. Fatigue and IPS were assessed using the Fatigue Scale for Motor and Cognitive Functions (FSMC) and the Symbol Digit Modalities Test (SDMT), respectively. Results No significant associations were found between GFAP or NfL levels and FSMC or SDMT scores. No significant differences in GFAP or NfL levels were observed between RTX‐ and NTZ‐treated groups. Conclusion No associations were found between fatigue, IPS, GFAP and NfL. GFAP and NfL levels in stable RRMS patients treated with off‐label RTX were low and did not significantly differ from those treated with NTZ, possibly suggesting a low risk of long‐term disability progression for patients treated with either therapy.
Hellgren et al. (2026) studied this question.