Coordinated and circumlocutory semantic naming errors are related to anterolateral temporal lobes in mild AD, amnestic mild cognitive impairment, and normal aging

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 (JINS 2010 16, 1099-1107)