Rethinking anomia across the frontotemporal dementia spectrum: marker of language dysfunction or global cognitive decline?
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Background
Anomia is common in frontotemporal dementia (FTD), although its clinical prominence varies by subtype, with the most marked impairment typically observed in primary progressive aphasia (PPA). It remains unclear whether naming impairment reflects language-specific impairment or broader cognitive severity, and how it relates to other cognitive domains across FTD syndromes.
Methods
Fifteen healthy controls and twenty-two individuals across the FTD spectrum, including variant-specified and unclassifiable (NOS) presentations, completed two confrontation naming tasks (Boston Naming Test and Multilingual Naming Test) and a global cognitive screening measure (Montreal Cognitive Assessment, MoCA). Patient participants additionally completed a standardized language battery (Western Aphasia Battery – Revised) and a comprehensive neuropsychological assessment (Uniform Data Set). Naming performance was compared between groups and associations with language severity, global cognition, and domain-specific cognitive functions were examined using regression analyses.
Results
Naming was impaired in patients relative to healthy controls but did not differ between patient groups. Naming was strongly associated with language severity, but not global cognition. A significant group-by-MoCA interaction indicated that MoCA was positively associated with naming only in the unclassifiable group. In addition, naming was associated with episodic memory across both verbal and non-verbal domains.
Conclusions
Naming in FTD primarily reflects language severity rather than global cognitive impairment. A robust association between naming and episodic memory suggests potential contributions from semantic cognition, shared frontally mediated retrieval processes, or parallel cognitive decline. These findings support the use of naming as a marker of language dysfunction while highlighting its relevance to broader cognitive systems in FTD.
What is already known on this topic
Although not a core diagnostic feature of the non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) or the behavioral variant of frontotemporal dementia (bvFTD), naming impairment is frequently reported in these groups, sometimes early in the disease course. More broadly, language deficits across FTD syndromes are heterogeneous and have been linked to global cognitive severity.
What this study adds
This study provides a systematic evaluation of naming across FTD, PPA, and unclassifiable (i.e., FTD/PPA NOS) presentations using validated language and cognitive measures, which are rarely applied together. We provide new evidence that naming in FTD primarily reflects language severity rather than global cognitive decline. Despite prior studies reporting episodic memory deficits in FTD syndromes such as bvFTD, the link between memory and naming has not previously been established, and here we identify a novel association with not only verbal, but also non-verbal domains.
How this study might affect research, practice or policy
While anomia may represent a transdiagnostic feature across FTD syndromes, its severity may index the degree of language impairment, supporting the use of naming as a practical marker of language severity in clinical assessment. The observed association with episodic memory provides a framework for interpreting memory profiles in the context of shared underlying mechanisms with naming, with implications for both clinical evaluation and future research.
