MAPT and Alzheimer disease: Compared to CSF A + T + individuals, CSF A + T − individuals may exhibit essentially indistinguishable clinical phenotypes which are associated with a greater number of co-pathologies but less extensive tau pathology (Table 3).This implies that Aβ positive cognitively impaired individuals with low tau levels, despite the presence of additional non-ADNC pathologies (i.e., mixed ADNC), may still respond better to Aβ-targeting therapy than their Aβ positive counterparts with high tau levels, who exhibit more advanced AD pathology [64].