NEFL and multiple system atrophy: The levels of blood NfL were clearly increased in PSP, MSA, and CBS when compared to controls (PSP, p < 0.001; MSA, p < 0.001; CBS, p < 0.001) and patients with PD (PSP, p < 0.001; MSA, p < 0.001; CBS, p < 0.001), with all analyses adjusted for age and sex (figure 2A).