TARDBP and amyotrophic lateral sclerosis: However, in ALS and PD, RN neuronal loss and/or loss of serotonergic projections due to marked and early TDP-43 and α-synuclein depositions in target areas might cause major imbalance in monoaminergic neurotransmission across the brain (Turner et al., 2005; Dentel et al., 2013; Politis and Niccolini, 2015), accounting for numerous motor, behavioral and cognitive dysfunctions.