In accordance with the idea that proSAAS plays a role in brain proteostasis, several groups have identified immunoreactive proSAAS within neurofibrillary tangles and neuritic plaques in brain tissue obtained from patients with Alzheimer’s disease (AD), Pick’s disease, and Parkinsonism-dementia complex (Helwig et al. 2013; Kikuchi et al. 2003; Wada et al. 2004). This evidence concerns the gene PCSK1N and early-onset autosomal dominant Alzheimer disease.