Primary progressive aphasia and the evolving neurology of the language network

Key Points Primary progressive aphasia (PPA) is a clinical syndrome caused by selective neurodegeneration of the language-dominant cerebral hemisphere, thus affecting the language network The language disorder manifest in patients with PPA can take the form of agrammatic, logopenic or semantic aphasia, depending on the anatomical distribution of cortical atrophy PPA can be caused by several types of neuropathology, including Alzheimer disease and frontotemporal lobar degeneration; these diseases tend to be associated with specific variants of PPA Concepts relating to Wernicke's area and anterior temporal lobe function need to be revised on the basis of the relationships identified between the clinical characteristics and neuroanatomy of peak atrophy sites in PPA PPA susceptibility, aetiology and pathogenesis, and the asymmetry of cerebral atrophy in particular, are poorly understood and require further elucidation Effective PPA treatments are urgently needed; development of such treatments should be considered a research area of importance