Abstract
We studied noun and verb naming in three main variants of frontotemporal dementia: the frontal variant(Fv-FTD), primary progressive aphasia (PPA) and semantic dementia (SD). We further distinguished PPA in nonfluent and fluent forms and restricted diagnosis of SD to subjects with progressive semantic breakdown leading to agnosia for words and objects. Fv-FTD and nonfluent-PPA named objects better than actions, SD showed an inverse dissociation and no specific pattern emerged in fluent-PPA. In this last group, in spite of the broad definition of fluent aphasia, quite heterogeneous patterns of language disorders and word class dissociation emerged when single-subject analyses were performed. In fv-FTD correlations between executive tasks and action naming were stronger than between executive tasks and object naming. We conclude that both linguistic and non linguistic factors, in particular an executive deficit, contribute to grammatical class dissociation. We also suggest that the fluent vs. nonfluent distinction does not reflect the complexity of primary aphasia.
Highlights
Selective impairment of grammatical classes of words has been consistently demonstrated in patients with brain lesions and specific anatomical substrates have been hypothesised for elaboration of nouns and verbs
Three had a disorder that could be classified as transcortical sensory aphasia (TCSA) with paraphasic production, good repetition and very poor comprehension of both spoken and written language; in two patients the salient feature was the presence of phonological errors (Phpatients) in production tasks, including repetition, but low comprehension did not allow classifying them as proper conduction aphasia patients; three patients had a semantic disorder that was similar to but not as selective as the one reported in semantic dementia and rather similar to the classical description of Wernicke’s aphasia (WA)
Noun deficit was clear in subjects with semantic dementia (SD) and verb deficit as well was clear in fv-frontotemporal dementia (FTD) and non fluent aphasics
Summary
Selective impairment of grammatical classes of words has been consistently demonstrated in patients with brain lesions and specific anatomical substrates have been hypothesised for elaboration of nouns and verbs. Ciccarelli / Naming of grammatical classes in frontotemporal dementias patients with primary language disorders, both fluent and nonfluent. We expected a disproportionate verb-naming deficit in subjects with nonfluent PPA in which a distribution of the damage in anterior brain regions could be presumed, and in subjects with fv-FTD that are supposed to be affected by dysexecutive disorders but not by aphasia. We expected a more severe nounnaming impairment in fluent PPA and in SD Since these two subgroups of patients, both affected by “fluent” language disorders, differed for clinical expression (and presumably for distribution of neural damage within the posterior brain regions) [9,43], we did not expect their word-class dissociation pattern to be necessarily homogeneous. At the same time we could corroborate the hypothesis that noun verb dissociation is multiply determined and that an executive deficit concurs in verb naming deficit
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