MAPT and diabetes mellitus: Cerebrovascular lesions, hypertension, diabetes and renal failure including other comorbidities28 can influence the permeability of the blood-brain-barrier and may also affect the metabolism of p-tau and the relationship with amyloid fibrils.29 Despite the numerous publications on plasma p-tau, to our knowledge, no previous study investigated its accuracy to predict amyloid status or the longitudinal changes in a very old cognitively unimpaired population.