Communication Dans Un Congrès Année : 2025

Lexical Ambiguity Processing in Alzheimer’s Disease: Evidence of Alterations in Executive and Lexico-Semantic Processes

Julien Dumurgier
Claire Paquet
Karin Heidlmayr

Résumé

Alzheimer’s disease (AD) and other neurodegenerative dementias (ND) are the most frequent causes for mild or major neurocognitive disorders (DSM-V; American Psychiatric Association, 2013). AD is characterised by a gradual decline of cognitive, emotional and behavioural capacities. With regard to language processing, deficiencies in lexico-semantic processing can be observed from the early stages on. The present study aims to investigate how these alterations in language processing affect the comprehension of contextually embedded homonyms, which are a case of lexical ambiguity in which words can take completely different meanings in different contexts. Previous work on the processing of lexical ambiguity in dementia patients has provided evidence on altered semantic word-meaning priming in this population (e.g., Chenery et al., 1998; Faust et al., 1997; Piccirilli et al., 2015; Taler et al., 2009). In the present study, 13 early stage dementia patients (age: 72.77 ± 6.39 years; MMSE: 23.54 ± 2.44) and 16 healthy age-matched control participants (age: 73.50 ± 4.79 years; MMSE: 29.50 ± 0.73) were exposed to French homonyms (e.g., palais) that were placed at the end of a short discourse which biased interpretation towards one of the word's meanings (dominant vs non dominant meaning; e.g., palais ‘palace’ vs. palais ‘palate’; see also, Dommes, 2006). Participants were asked to carry out a semantic similarity judgement between the meanings of the discourse context and a subsequent target word that was either semantically compatible with the discourse context (e.g., monument ‘monument’), incompatible but related to the contextually irrelevant meaning of the homonym (e.g., bouche ‘mouth’), or incompatible and fully unrelated to any of the meanings of the homonym (e.g., radio ‘radio’). There was a main effect of semantic compatibility on response times (incompatible related > incompatible unrelated > compatible), suggesting a partial co-activation of both meanings of homonyms requiring the inhibition of the contextually irrelevant meaning. Moreover, there was a main effect of group with dementia patients showing overall slower response times and higher error rates compared to healthy controls. Importantly, there was also a group by context interaction on error rates. Post-hoc analyses revealed that dementia patients showed higher error rates when confronted to a meaning-dominant context for the embedded homonyms, especially when they had to reject semantically incompatible related target words. Finally, error rates were found to be negatively related to both, independent measures of executive control (BREF, Batterie Rapide d'Efficience Frontale) and of lexico-semantic processing (TLE, Test de Langage élaboré; Rousseaux & Cas, 2012), suggesting a joint contribution of executive and lexico-semantic deficits in lexical ambiguity processing in Alzheimer’s disease. Taken together, these findings suggest that Alzheimer’s patients suffer from an insufficient inhibition of contextually irrelevant meanings of ambiguous words placed in a discourse context, but also from a degradation of semantic representations as such, affecting more strongly the dominant meaning. Further research should shed light on the online influence of context during lexical access in cases of lexical ambiguity, e.g. using electroencephalographic measures, in dementia patients and healthy controls. References American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (DSM-5®). American Psychiatric Pub. Chenery, H. J., Ingram, J. C. L., & Murdoch, B. E. (1998). The resolution of lexical ambiguity with reference to context in dementia of the Alzheimer’s type. International Journal of Language & Communication Disorders, 33(4), 393–412. https://doi.org/10.1080/136828298247703 Dommes, A. (2006). La compréhension d’ambiguïtés lexicales présentées dans différents contextes phrastiques et discursifs chez des adultes jeunes et âgés: Effets des contraintes contextuelles introduites et de la familiarité des sens des mots ambigus [PhD Thesis]. Université Paris Nanterre. Faust, M. E., Balota, D. A., Duchek, J. M., Gernsbacher, M. A., & Smith, S. (1997). Inhibitory Control during Sentence Comprehension in Individuals with Dementia of the Alzheimer Type. Brain and Language, 57(2), 225–253. https://doi.org/10.1006/brln.1997.1747 Piccirilli, M., D’Alessandro, P., Micheletti, N., Macone, S., Scarponi, L., Arcelli, P., Petrillo, S. M., Silvestrini, M., & Luzzi, S. (2015). Impairment of homonymous processing in Alzheimer’s disease. Neurological Sciences, 36(8), 1331–1336. https://doi.org/10.1007/s10072-015-2085-5 Rousseaux, M., & Cas, P. D. (2012). TLE: test de langage élaboré pour adultes. Ortho éd. Taler, V., Klepousniotou, E., & Phillips, N. A. (2009). Comprehension of lexical ambiguity in healthy aging, mild cognitive impairment, and mild Alzheimer’s disease. Neuropsychologia, 47(5), 1332–1343. https://doi.org/10.1016/j.neuropsychologia.2009.01.028

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hal-05228053 , version 1 (28-08-2025)

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  • HAL Id : hal-05228053 , version 1

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Camille Rostand, Marie Thébaut, Julien Dumurgier, Claire Paquet, Karin Heidlmayr. Lexical Ambiguity Processing in Alzheimer’s Disease: Evidence of Alterations in Executive and Lexico-Semantic Processes. 58th Annual Meeting of the Societas Linguistica Europaea (SLE), Societas Linguistica Europaea, Aug 2025, Bordeaux, France. ⟨hal-05228053⟩
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