MAPT and Alzheimer disease: Similarly, previous studies have shown that the core CSF biomarkers used to support AD diagnosis (amyloid β peptide (Aβ1-42), total tau (tTau) and phosphorylated tau (pTau))14 provide limited diagnostic accuracy for discriminating DLB from AD since they are also abnormal in almost 25–40% of DLB patients due to the presence of comorbid AD pathology15–18.