ABSTRACT
Introduction Aphasia can arise not only abruptly as a result of a sudden brain injury, but also gradually as a consequence of a neurodegenerative disease. During the past few decades, an increasing amount of research has focused on a closely related set of neurodegenerative conditions in which insidiously declining language abilities are the most salient clinical features and the principal cause of restrictions in daily life. These conditions fall under the rubric of what is called primary progressive aphasia (PPA).
