Mechanistic links between cadmium and MAPK pathways leading to neurodegeneration.

Cadmium, a Group 1 carcinogen, represents a significant public health concern due to its widespread environmental distribution and exposure through industrial processes, contaminated water, dietary intake, and tobacco use. Prolonged cadmium exposure is associated with systemic toxicity, including neurodegenerative outcomes mediated by oxidative stress, protein misfolding, neuroinflammation, and mitochondrial dysfunction. Disruption of autophagy and MAPK signalling pathways (ERK, JNK, and P38) further impairs neuronal function. Cadmium-induced misfolding of key proteins such as tau, amyloid-β, and α-synuclein is implicated in Alzheimer's and Parkinson's diseases. This systematic review aims to map the role of cadmium exposure in neurodegenerative disorders, with a focus on oxidative stress, protein misfolding, autophagy dysregulation, and MAPK signalling pathways. A thorough literature search was conducted across databases including PubMed, Scopus, and Science Direct using specific keywords. Elevated markers, including IL-6, IL-8, and cytochrome c, may serve as diagnostic indicators of cadmium-associated neurodegeneration.