BDNF serum levels with respect to multidimensional assessment in amyotrophic lateral sclerosis

Background: The clinical presentation of amyotrophic lateral sclerosis (ALS) is characterized by high heterogeneity, the greatest part of which still remains unexplained. Objective: To assess serum levels of brain-derived neurotrophic factor (BDNF) in ALS patients, implementing a multidimensional characterization focused on four a priori chosen elements of phenotypic variability: ALS bulbar/spinal subtype, cognitive impairment, mood dysfunction and disease progression speed. Methods: Serum samples were obtained from 45 ALS outpatients (16% bulbar onset) and 22 healthy controls. Each patient underwent the Montreal Cognitive Assessment (MoCA) and the Beck Depression Inventory (BDI), and disease progression speed was estimated by calculating the decay of the ALSFRS-R score over time. Results: BDNF serum levels did not differ between patients and controls, although ∼25% lower levels characterized those patients carrying a depressive trait. Finally, BDNF serum levels were significantly lower in ALS patients expressing lower ALSFRS-R scores (r = 0.39, p < 0.01). No differences were found when considering cognitive impairment, disease progression speed and site of onset. Conclusion: BDNF serum levels might mark and possibly contribute in part to ALS phenotypic variability.