MAPT and frontotemporal dementia: The methylthioninium (MT) moiety can exist in oxidised (MT+) and reduced (LMT) forms and we have reported recently that LMTM blocks tau aggregation and propagation in vitro [46], reverses behavioural deficits and tau pathology in mice [47] and hydromethylthionine has pharmacological activity on brain structure and function in both AD [48] and FTD [49].