MAPT and Alzheimer disease: Most importantly clinical trials aiming at amyloid plaques highlighted the lack of in depth understanding of (i) the molecular identity of the toxic Aβ (and Tau) forms, (ii) the mechanisms linking both diagnostic pathologies (amyloid and Tau) – and eventually associated pathological features including inflammation, synaptic loss, brain atrophy and (iii) the respective contributions of both pathological proteins to the etiology of AD.