NEFL and systemic lupus erythematosus: Higher plasma NfL concentrations were observed in SLE patients with impairment in the domains of psychomotor speed and verbal memory (median plasma NfL (range) 10.9 (8.4–13.4) pg/ml versus 7.1 (3.1–20.5) pg/ml, p = 0.012, and 8.2 (7.1–13.6) pg/ml versus 6.8 (3.1–20.5) pg/ml, p = 0.024, respectively).