Hair metal dysregulation in Parkinson's disease: Implications for diagnosis and gut-brain axis involvement.

This study investigated hair metals as potential biomarkers in Parkinson's disease (PD) and their link to gut-mediated iron metabolism. In 60 PD patients and matched controls, hair analysis revealed a distinct profile: significantly lower iron and copper, higher manganese and arsenic, and unchanged zinc levels, with combined metals showing diagnostic value (e.g., Cu AUC = 0.79). Using an MPTP-induced mouse model, we linked lower hair iron to gut pathophysiology, finding impaired intestinal barrier integrity, downregulated host iron absorption genes (DMT1 and FPN), and upregulated microbial iron-acquisition genes (e.g., fepG). These results suggest that gastrointestinal dysfunction and gut microbiota dysbiosis may contribute to systemic iron deficiency in PD. Hair multi-metal analysis shows promise as a diagnostic adjunct, reflecting the involvement of the gut-brain axis and highlighting a potential target for intervention.