Different forms of tau aggregates/fibrils are found in different tauopathies but whether these are associated with specific neuronal cell death mechanisms remains to be determined. Two forms are illustrated in the central diamond-labelled tauopathies, the upper image shows two Pick bodies, while the lower image shows a neuronal tau tangle from an AD brain. Staining is with the anti-phospho-Ser^202/205 antibody AT8 followed by immunohistochemistry with diaminobenzidine (DAB). The different colours under the various headings indicate separate mechanisms. Abbreviations: GPX4, glutathione peroxidase 4; ER, endoplasmic reticulum; UPR, unfolded protein response (induced by ER stress); Xc⁻, the glutamate/cystine transporter encoded by the SLC7A11 gene.