NEFL and Guillain-Barre syndrome: Peak NfL was also significantly higher in GBS (median 220.8 pg/ml) than CIDP (17.3 pg/ml), multiple sclerosis (21.5 pg/ml), dementia (29.9 pg/ml) and healthy controls (5.6 pg/ml), Peak NfL levels also distinguished between controls and all other disease groups, but were not able to distinguish between CIDP, multiple sclerosis and dementia.