PSEN1 and familial Alzheimer disease: CWPs have been described in fAD patients with various PSEN1 mutations.27,28,72−75 Morphologically, in the electron microscope, the presence of Aβfibrils can be found throughout the CWP, but the number can be small,and they are not forming compact cores.74,75 In addition,CWPs are often noncongophilic and show weak ThS fluorescence.27 Hence, although the fibrillar structure andthe tinctorial properties of CWPs resemble the properties of diffuseplaques, they are still LL-1 positive, indicating that the formationof a binding site for this ligand does not require a dense arrangementof filaments.