Morphosyntactic production in Greek- and Italian-speaking individuals with probable Alzheimer’s disease: evidence from subject–verb agreement, tense/time reference, and mood

ABSTRACT

Background: In probable Alzheimer’s disease (AD), different memory systems, executive functioning, visuospatial recognition, and language are impaired. Regarding the latter, only a few studies have investigated morphosyntactic production thus far.

Aims: This study, which is a follow-up on Fyndanis, V., Manouilidou, C., Koufou, E., Karampekios, S., and Tsapakis, E. M. (2013). Agrammatic patterns in Alzheimer's disease: Evidence from tense, agreement, and aspect. Aphasiology, 27, 178–200. doi:10.1080/02687038.2012.705814, investigates whether verb-related morphosyntactic production is (selectively) impaired in AD focusing on two highly inflected languages, Greek and Italian. The morphosyntactic phenomena explored are subject–verb Agreement, Tense/Time Reference, and Mood. Focusing on these phenomena allows us to investigate if recent hypotheses, originally developed in aphasia research, can also capture results related to AD. We tested the hypotheses discussed in Fyndanis, V., Manouilidou, C., Koufou, E., Karampekios, S., and Tsapakis, E. M. (2013). Agrammatic patterns in Alzheimer's disease: Evidence from tense, agreement, and aspect. Aphasiology, 27, 178–200. doi:10.1080/02687038.2012.705814, that is, the Interpretable Features’ Impairment Hypothesis (IFIH) (e.g., Fyndanis, V., Varlokosta, S., & Tsapkini, K. 2012. Agrammatic production: Interpretable features and selective impairment in verb inflection. Lingua, 122, 1134–1147. doi:10.1016/j.lingua.2012.05.004) and the PAst DIscourse LInking Hypothesis (PADILIH; Bastiaanse, R., Bamyaci, E., Hsu, C., Lee, J., Yarbay Duman, T., & Thompson, C. K. 2011. Time reference in agrammatic aphasia: A cross-linguistic study. Journal of Neurolinguistics, 24, 652–673. doi:10.1016/j.jneuroling.2011.07.001).

Methods & Procedures: Two sentence completion tasks testing the production of subject–verb Agreement, Tense/Time Reference, and Mood were administered to 16 Greek-speaking and 10 Italian-speaking individuals with mild-to-moderate AD, as well as to 16 Greek-speaking and 11 Italian-speaking neurologically intact individuals who were matched with the participants with AD on age and education. Mixed-effects models were fitted to the data.

Outcomes & Results: At the group level, both the Greek and Italian participants with AD performed worse than the controls. Both AD groups revealed selective patterns of morphosyntactic production (Greek: Agreement/Mood > Time Reference; Italian: Agreement > Time Reference > Mood). Past Reference and Future Reference did not dissociate in either of the two AD groups. Nevertheless, in all four participants with AD who showed dissociations, Past Reference was more impaired than Future Reference.

Conclusions: The results indicate that the production of verb-related morphosyntactic categories can be impaired in mild-to-moderate AD. The different patterns observed in the two languages are partly attributable to the different way these languages encode Mood. The group results (of both the Greek- and Italian-speaking participants with AD) do not lend support to the PADILIH, whereas only the results of the Italian AD group are fully consistent with the IFIH. However, the individual data are consistent with the PADILIH, and the IFIH is informed by the present data and modified accordingly so that it can capture cross-linguistic patterns of morphosyntactic impairment.

KEYWORDS:

• Morphosyntactic production
• Alzheimer’s disease
• subject–verb agreement
• tense/time reference
• mood

Acknowledgments

We are grateful to all individuals who took part in this study. We also thank Fabiana Galiussi for helping with data transcription, the Guest Editor of this Special Issue, Carol Leonard, three anonymous reviewers, and Hanne Gram Simonsen, Ruggerro Bellio, Athanassios Protopapas, Charalambos Themistokleous, Maria Varkanitsa, Francesca Franzon, and Chiara Zanini for their useful comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. The hypotheses discussed here were originally formulated for agrammatic aphasia (Bastiaanse et al., 2011; Fyndanis et al., 2012) but there is evidence that they can also account for patterns of performance exhibited by individuals with non-agrammatic aphasia (see, e.g., the three individuals with transcortical motor aphasia reported by Rofes, Bastiaanse, & Martínez-Ferreiro, 2014, as well P1 and P7 reported by Varlokosta et al., 2006).

2. In Greek, regular verbs are those whose past tense formation is rule governed (see Ralli, 1988). In Italian, regular verbs are those that form the past participle by changing the suffix of their infinitival form only (e.g., am-a-re [infinitive] > am-a-to [past participle], dorm-i-re [infinitive] > dorm-i-to [past participle]) (Colombo et al., 2009).

Additional information

Funding

This research was supported by a Marie Curie Intra-European Fellowship (awarded to the first author) within the 7th European Community Framework Programme, project reference 329795, and by the Research Council of Norway through its Centres of Excellence funding scheme, project number 223265.