FIGURE 2.

(a) Serum neurofilament light chain (NfL) levels in patients with amyotrophic lateral sclerosis (ALS) grouped according to previously published criteria [41] (b) Serum glial fibrillary acidic protein (GFAP) levels in ALS patients classified according to cognitive impairment [43] Boxes are median and interquartile range. Whiskers are highest and lowest values. Biomarker levels are plotted on a 10‐logarithmic scale. *p < 0.05, **p < 0.01. ci/bi/cbi, cognitive impairment/behavioral impairment/both; FA, flail arm; FL, flail leg; FTD, frontotemporal dementia; PLMN, pure lower motor neuron; PUMN, pure upper motor neuron