MAPT and Alzheimer disease: For instance, in variant carriers, high levels of cortical amyloid burden have been observed at a mean age of 28 years54 and elevated regional tau levels in the medial temporal lobe at a mean age of 38 years.55 Previous studies29,56 have found that self-reported memory complaints in a subset (n = 21) of unimpaired variant carriers of the Colombian kindred were associated with biomarkers of AD pathology.