APOE and primary progressive aphasia: In fact, the ε4 allele of ApoE, which is a major risk factorfor Alzheimer pathology in amnestic dementias, is not a risk factor for the type ofAlzheimer pathology that causes PPA.43,44 Amyloid imagingwith PET and cerebrospinal fluid evaluations for phosphotau and beta amyloid may behelpful for the identification of patients with AD pathology.45 A rapidly progressive languagedisorder with all the initial characteristics of PPA has been described inconjunction with Jacob-Creutzfeldt disease.