Both metals enhance tau protein phosphorylation, leading to neurofibrillary tangles (Huat et al., 2019), and may increase amyloid-beta production and aggregation (Ricchelli et al., 2005; Drago et al., 2008; Boopathi and Kolandaivel, 2016), contributing to Alzheimer's disease. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.