MAPT and Alzheimer disease: HB can only definitely be identified by electron microscopy (EM) 21, but (i) the found inclusions closely resembled previously published images of HB 39, (ii) the inclusions, just like HB, were primarily found in the CA1 of AD patients 37 and (iii) the inclusions co‐localized to some extent with p‐tau positive tangles, which is characteristic for HB 15.