TARDBP and amyotrophic lateral sclerosis: TDP-43<sup>APT</sup> staining intensity is also associated with increased ferritin, regardless of behavioural phenotype, suggesting that ferritin increases may occur upstream of clinical manifestation, in line with early TDP-43<sup>APT</sup> pathology, representing a potential region-specific imaging biomarker (e.g. volumetric or susceptibility-weighted MR imaging) of early disease in ALS.