title: Coordinated and circumlocutory semantic naming errors are related to anterolateral temporal lobes in mild AD, amnestic mild cognitive impairment, and normal aging.
abstract: Naming difficulties are characteristic of Alzheimer's disease (AD) and, to a lesser extent, of amnestic mild cognitive impairment (aMCI) patients. The association of naming impairment with anterior temporal lobe (ATL) atrophy in Semantic Dementia (SD) could be a tip of the iceberg effect, in which case the atrophy is a marker of more generalized temporal lobe pathology. Alternatively, it could reflect the existence of a functional gradient within the temporal lobes, wherein more anterior regions provide the basis for greater specificity of representation. We tested these two hypotheses in a study of 15 subjects with mild AD, 17 with aMCI, and 16 aged control subjects and showed that coordinate and circumlocutory semantic error production on the Boston Naming Test was weakly correlated with ATL gray matter density, as determined by voxel-based morphometry. Additionally, we investigated whether these errors were benefited by phonemic cues, and similarly to SD, our AD patients had small improvement. Because there is minimal gradient of temporal lobe atrophy in AD or MCI, and, therefore, no basis for a tip of the iceberg effect, these findings support the theory of a modest functional gradient in the temporal lobes, with the ATLs being involved in the naming of more specific objects.
authors.affiliation: Neuropsychology and Neurolinguistics Unit, Department of Neurology, Medical School, University of Campinas (UNICAMP), Brazil. mbalth@gmail.com
authors.forename: Marcio Luiz Figueredo
authors.initials: ML
authors.lastname: Balthazar
authors.forename: Clarissa Lin
authors.initials: CL
authors.lastname: Yasuda
authors.forename: Fabrício Ramos Silvestre
authors.initials: FR
authors.lastname: Pereira
authors.forename: Felipe Paulo Guazzi
authors.initials: FP
authors.lastname: Bergo
authors.forename: Fernando
authors.initials: F
authors.lastname: Cendes
authors.forename: Benito Pereira
authors.initials: BP
authors.lastname: Damasceno
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology*; D000647:Amnesia / Q000473:pathology*; D003072:Cognition Disorders / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009275:Names; D009483:Neuropsychological Tests; D012660:Semantics; D013223:Statistics as Topic; D013702:Temporal Lobe / Q000502:physiology / Q000503:physiopathology*