Biomarkers in the primary progressive aphasias
Primary progressive aphasia (PPA) is a progressive disorder of language that is increasingly recognised as an important presentation of a specific spectrum of neurodegenerative conditions.In an era of etiologically specific treatments for neurodegenerative conditions, it is crucial to establish the histopathologic basis for PPA. In this review, I discuss biomarkers for identifying the pathology underlying PPA.Clinical syndromes suggest a probabilistic association between a specific PPA variant and an underlying pathology, but there are also many exceptions. A considerable body of work with biomarkers is now emerging as an important addition to clinical diagnosis. I review genetic, neuroimaging and biofluid studies that can help determine the pathologic basis for PPA.Together with careful clinical examination, there is great promise that supplemental biomarker assessments will lead to accurate diagnosis of the pathology associated with PPA during life and serve as the basis for clinical trials in this spectrum of disease.