Comparative Neuroanatomy of Object and Generative Naming Impairment in Behavioral Variant Frontotemporal Dementia and Primary Progressive Aphasia
Grace Lee1, Jordan Behn1, Elena Barbieri2, Borna Bonakdarpour2
1Mesulam Center, Mesulam Center for Cognitive Neurology and Alzheimer Disease, 2Mesulam Center for Cognitive Neurology and Alzheimer Disease
Objective:
The purpose of this study was to investigate patterns of grey matter (GM) atrophy underlying disrupted object and generative naming in bvFTD and PPA to compare the neuroanatomic features of both syndromes.
Background:
Behavioral variant frontotemporal dementia (bvFTD) and primary progressive aphasia (PPA) both present with impairments in naming and word finding.
Design/Methods:
Participants in this study included 143 bvFTD, 69 PPA, and 118 healthy controls from the All FTD Research Study. Boston Naming Test (BNT), and Multilingual Naming Test (MINT) were used as object naming measures. Generative naming was evaluated using animal and vegetable fluency tests. Benson Complex test was used as a control measure of visuospatial function. Voxel-based morphometry (VBM) was performed in CAT12 toolbox to visualize atrophy patterns and regression analyses.
Results:
The findings demonstrate a correlation between bilateral temporal lobe and both object and generative naming in bvFTD and PPA. PPA had greater atrophy in the left hemisphere. Impairment in categorical fluency was also correlated to atrophy in the bilateral frontal lobe but only in the bvFTD group. Lower Benson complex test scores correlated to atrophy in the dorsal parietal lobes in bvFTD and PPA, which were distinct from perisylvian language zone.
Conclusions:
The findings indicate picture naming in both syndromes was associated with temporal lobe cortical volume, this association was uniquely asymmetric (left atrophy > right) in PPA. Also, while generative naming impairment depended on atrophy in temporal lobes for both groups, it was only associated with cortical volume loss in the frontal regions in bvFTD, suggesting a greater association with executive failure. There was a double dissociation between atrophy patterns for naming and visual tasks points to the specificity of our findings. Our findings help us better understand the underlying pathophysiology of naming failure in bvFTD and PPA.
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