Strikingly, only a small portion of the AT8 + tau aggregates in the synaptic and extra-synaptic fractions were longer than 150 nm in length and showed high eccentricity, suggesting the lack of an elongated morphology (Fig. 1f), but the concentration of these species was higher in the synaptic fraction of AD cases (around 15%). Here, MAPT is linked to Alzheimer disease.