Spermidine, an autophagy-triggering compound, has been shown to increase lifespan in several models and protect against toxicity from pesticide paraquat, which has been linked to Parkinson’s disease (PD) and alpha-synuclein (α-Syn), a key protein found to play a role in the pathology of PD [127,148,149]. The gene discussed is SNCA; the disease is Parkinson disease.