Review synthesizing spermidine's mechanisms, preclinical neuroprotective data, and clinical perspectives in the aging brain, highlighting autophagy induction, mitochondrial support, and anti-inflammatory effects.

Spermidine engages pathways (autophagy, mitochondrial health, inflammation) directly relevant to alpha-synuclein clearance and neurodegeneration and represents a repurposable, translational candidate for Parkinson's-focused interventions.