Semantic Dementia and Primary Progressive Aphasia: A Problem of Categorization?

Abstract:
The relationship between semantic dementia (SD) and primary progressive aphasia (PPA) has been the subject of debate ever since the syndromes were first described, in converging streams of research from the neuropsychological and neurologic communities. The most salient clinical features of SD are anomia with circumlocution and semantic paraphasia, single-word comprehension deficit, and reduced category fluency. Of critical importance is the fact that patients also show deficits on non-verbal tasks using visual, auditory, and other modalities, suggesting that the key impairment in SD is a breakdown in conceptual knowledge rather than a specific problem with language. The finding of item consistency between the various tests supports this view. The order in which the features appear can be explained by the variable degree of redundancy in access to semantic knowledge from…

Read more…