Sources of Oxidative Stress in Parkinson's Disease: Pathways and Therapeutic Implications.

Parkinson's disease (PD) is a heterogeneous neurodegenerative disorder in which oxidative stress represents a final common pathway linking diverse genetic and environmental insults to dopaminergic neuron loss. This review synthesizes evidence on how the commonly observed pathological changes in PD converge on excessive reactive oxygen species generation and redox imbalance. We present an overview on these pathways and key PD-linked genes that perturb mitochondrial quality control, lysosomal function, and inflammatory signaling, reinforcing oxidative stress. The major classes of redox-targeted therapeutic strategies under preclinical and clinical evaluation are outlined. Although many candidates show robust target engagement and neuroprotection in models, clinical trials have frequently yielded neutral or modest results, highlighting challenges related to brain delivery, off-target effects, optimal treatment window, and the fact that oxidative stress alone may be necessary but not sufficient to drive human disease progression. In the current paper, beyond cataloguing oxidative pathways, we explain the role of etiologic heterogeneity on biochemical target engagement and clinical outcomes. We outline subtype-enriched trial strategies and rational combination approaches. Targeting oxidative stress-related pathways thus remains a promising avenue for disease modification in PD, provided that future interventions are mechanistically informed and adapted to patient-specific redox vulnerabilities.