VGF and Parkinson disease: Clinical and preclinical studies link VGF-derived peptides to other neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) [18,19,20,21], frontotemporal dementia (FTD) [22], Parkinson’s disease (PD) [23] and AD [15,23,24,25,26,27,28,29,30,31,32].