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Nonfluent progressive aphasia and semantic dementia: A comparative neuropsychological study
Authors:
Hodges, J.R. & Patterson, K.
Reference:
Journal of the International Neuropsychological Society, 2, 511-524
Year of publication:
1996
CBU number:
3418
Abstract:
Two patients with non-fluent progressive aphasia, who have been studied longitudinally,are contrasted with a group of five patients with fluent progressive aphasia or semantic dementia. The most prominent feature of non-fluent syndrome is the severe distortion of speech output with phonological errors and agrammatic sentence structure. This contrasts with fluent, articulated and syntactically correct, but empty anomic speech found in semantic dementia. Performance on tests of comprehension separates the patient groups; the non-fluent patients show normal single-word comprehension but marked impairment on tests of syntactic comprehension, while those with semantic dementia demosntrate the opposite pattern. Category fluency is severely defective in semantic dementia, but initial letter-based fluency is more impaired in the non-fluent syndrome. Performance on non-verbally mediated tests of semantic knowledge is is impaired in semantic dementia only. The two forms of progressive aphasia have in common the sparing of perceptual and visuo-spatial skills, non-verbal problem solving abilities and day-to-day (episodic) memory. Neuroradiological investigations have shown marked selective and striking infero-lateral left temporal lobe atrophy in all five patients with semantic dementia: the changes in non-fluent progressive aphasia apppear to be less focal and involve left perisylvan structure more diffusely. These two forms of progressive aphasia are, we argue, distinct in their manifestations.