Abstract
Bilingual aphasia rehabilitation faces the challenge of determining which language to target in therapy to maximize recovery across both languages. This double-blind randomized controlled trial (48 Spanish–English bilinguals with chronic aphasia; NCT02916524) evaluated whether the BiLex computational model could predict the optimal language for aphasia therapy. Participants received 40 h of semantic feature-based treatment in either the BiLex-recommended language or the opposite language. Both groups showed similar gains in treated-language naming, with no significant difference in proportion of maximal improvement (Difference (SE) = –0.03 (0.07); t = –0.46; p = 0.65). However, the model-opposite group showed significantly greater cross-language generalization (Difference (SE) = –0.16 (0.07); t = –2.38; p = 0.02), though with higher response variability. Further, when the participants were divided into subgroups according to performance, the model-assigned group had a significant advantage in all but the lowest performing subgroups. All these differences were consistent with BiLex model predictions.
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Data availability
If researchers request specific patient data, we will provide our research data in a deidentified/anonymized format following a data-sharing agreement between the two parties. In particular, all datasets made available for sharing shall be modified to minimize the possibility of participant identification and to be fully compliant with HIPAA regulations. The final dataset will be stripped of participant identifiers and made available in the form of spreadsheets.
Code availability
All the code generated from this project is shared on a GitHub repository (https://github.com/nnrg/BiLex). The code is freely available to any researcher.
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Acknowledgements
This research was supported by U01 DC014922 awarded to Swathi Kiran and Risto Miikulainen. Additionally, Marissa Russell-Meill, Erin Carpenter, Manuel Marte, and Michael Scimeca were partially supported by T32 DC013017. Claudia Peñaloza was supported by grant RYC2021-034561-I funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR during the writing of the manuscript. The authors wish to thank the participants and their families for participating in the study.
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S.K.—Conceptualization, funding acquisition, investigation, methodology, project administration, resources, supervision, validation, visualization, writing—original draft, and writing—review and editing. E.C.—Data curation, formal analysis, investigation, methodology, project administration, visualization, writing—original draft, and writing—review and editing. U.G.—Conceptualization, data curation, formal analysis, investigation, methodology, project administration, resources, software, validation, visualization, writing—original draft, and writing—review and editing. M.S.—Data curation, formal analysis, investigation, methodology, project administration, visualization, writing—original draft, and writing—review and editing. M.M.—Data curation, formal analysis, investigation, methodology, project administration, visualization, writing—original draft, and writing—review and editing. M.R.M.—Data curation, formal analysis, investigation, methodology, project administration, visualization, writing—original draft, and writing—review and editing. C.P.—Data curation, formal analysis, investigation, methodology, project administration, visualization, writing—original draft, and writing—review and editing. Y.T.—Investigation, methodology, supervision, validation, visualization, and writing—review and editing. R.M.—Conceptualization, funding acquisition, investigation, methodology, project administration, resources, supervision, validation, visualization, writing—original draft, and writing—review and editing. All authors reviewed the manuscript.
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Kiran, S., Carpenter, E., Grasemann, U. et al. Predicting bilingual aphasia treatment outcomes using digital twins: a double-blind randomized controlled trial. npj Digit. Med. (2026). https://doi.org/10.1038/s41746-026-02583-9
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DOI: https://doi.org/10.1038/s41746-026-02583-9
