MAPT and Alzheimer disease: The late-onset AD group also demonstrated smaller parietal/occipital lobe volumes in comparison with the DLB, FTLD-tau and TDP43C groups (figures 2 and 3), in keeping with reported disruption to the brain’s default mode network due to AD pathology.20 This was also evident in the other Alzheimer’s pathology groups, with additional involvement of the anterior cingulate cortex.