MAPT and Alzheimer disease: In human AD samples, the accumulation of hyperphosphorylated tau in a pretangle state does not seem to induce changes in the dendrites of pyramidal neurons, whereas the presence of intraneuronal neurofibrillary tangles has been associated with loss of dendritic spines and dendrite atrophy, including alterations in dendritic spine head volume and dendritic spine length (Merino-Serrais et al.