Interestingly, elevated circulating p75NTR ECD levels are observed in Alzheimer’s disease and major depressive disorders (Zhou et al., 2013; Jiao et al., 2015), while high urinary p75NTR levels are reported in amyotrophic lateral sclerosis (ALS) and Huntington’s disease patients (Shepheard et al., 2014, 2017; Jia et al., 2017; Simmons et al., 2021). This evidence concerns the gene NGFR and early-onset autosomal dominant Alzheimer disease.