Oxidative Stress as a Central Mechanistic Bridge Between Alzheimer’s and Vascular Pathologies in Mixed Dementia: Emerging Evidence and Therapeutic Perspectives

Mixed dementia (MD), characterized by overlapping features of Alzheimer’s disease (AD) and vascular dementia (VaD), represents the most prevalent form of late-life cognitive decline. Increasing evidence identifies oxidative stress as a unifying molecular mechanism driving both neurodegenerative and vascular pathologies in MD. Reactive oxygen species (ROS) contribute to amyloid-β aggregation, tau hyperphosphorylation, endothelial dysfunction, and blood–brain barrier disruption, creating a self-perpetuating cycle of neuronal and vascular injury. Mechanistic models demonstrate how chronic hypoperfusion and mitochondrial dysfunction exacerbate ROS generation and neuroinflammation, while impaired Nrf2-mediated antioxidant defense further amplifies damage. Therapeutically, classical antioxidants show inconsistent efficacy, shifting focus toward mitochondrial protection, Nrf2 activation, and lifestyle-based oxidative load reduction. Therefore, we sought to outline therapeutic approaches capable of broadly targeting these mechanisms, through focused narrative analysis of recent studies employing delivery systems for antioxidant proteins and/or redox-regulating miRNAs. In particular, experimental interventions using mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) demonstrate neuroprotective and anti-inflammatory effects via the Nrf2 pathway, suggesting promising avenues for multimodal treatment. Integrating oxidative, vascular, and neurodegenerative paradigms is essential for advancing diagnostic precision and developing targeted interventions capable of addressing the complex pathophysiology of mixed dementia.