Neurotoxic mechanisms of cadmium in neurodegenerative diseases

Cadmium (Cd) is a highly toxic, bioaccumulative heavy metal increasingly implicated in the pathogenesis of neurodegenerative disorders. This review systemically characterizes the molecular mechanisms underlying Cd-induced neurotoxicity, with particular emphasis on oxidative stress-mediated pathways that initiate interconnected processes including ferroptosis, mitochondrial impairment, disruption of calcium homeostasis, and chronic neuroinflammation. Evidence indicates that Cd exerts both convergent and disease-specific effects in neurodegenerative conditions. In Alzheimer's disease (AD), Cd exposure has been associated with enhanced amyloid-β (Aβ) deposition and increased tau hyperphosphorylation. In Parkinson's disease (PD), Cd disrupts metabolic homeostasis via the gut-liver-brain axis and promotes aberrant conformational changes and aggregation of α-synuclein (α-Syn). Within the amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) spectrum, Cd contributes to TDP-43 proteinopathy and impairs nucleocytoplasmic transport mechanisms. Therapeutic strategies targeting Cd-induced neurotoxicity are also explored, including upstream approaches like metal chelation and downstream interventions aimed at restoring autophagic flux, modulating the neuroimmune microenvironment, and enhancing neuronal repair. Although emerging platforms such as brain organoids provide valuable mechanistic insights, translating findings from in vitro models to real-world chronic exposure scenarios remains a significant challenge. This review provides a comprehensive framework for the development of early-warning systems and precision-based interventions for Cd-related neurodegeneration.