[Progressive aphasia. New data on an old phenomenon].

Progressive aphasias are distinct but infrequently recognized clinical expressions of non-Alzheimer lobar atrophy. We review and illustrate two such syndromes--semantic dementia (SD) and progressive nonfluent aphasia (PA). SD involves loss of conceptual structure due to bilateral infratemporal atrophy. PA is a phonetic-syntactic disorder resulting from left perisylvian atrophy. Early research on Pick disease--originally defined as circumscribed cerebrocortical atrophy--highlighted left temporal lobe atrophy and aphasia. For this reason (among others), Pick disease or Pick complex is still a useful and convenient label for progressive aphasias and other clinical manifestations of non-AD lobar atrophy.