BDNF and amyotrophic lateral sclerosis: Interestingly, in a cohort of serum samples from 45 ALS outpatients (16% bulbar onset), BDNF serum levels were significantly lower in ALS patients expressing lower ALSFRS-R scores (r = 0.39, p < 0.01), which is a predictor for ALS-progression (Tremolizzo et al., 2016).