Executive functions, word fluency, and metaphor comprehension in young people with cochlear implants

Purpose: The long-term effects of early cochlear implantation (CI) on higher- level language and cognitive abilities in adolescence are not well understood. This thesis examined whether adolescents and young adults with early CI show language and cognitive skills comparable to peers with typical hearing (TH), focusing on executive functions, word fluency, and metaphor comprehension, and explored the influence of age at implantation. Methods: Participants included 43 adolescents and young adults with cochlear implants (mean age 16.9 years, mean implantation age 15.6 months) and 27 peers with typical hearing (mean age 14.9 years). Cognitive and language abilities were assessed using standardized tests and experimental tasks. Executive functions and communicative skills were also evaluated via self- and parent-report questionnaires. Metaphor comprehension was assessed with a newly developed multiple-choice task. Word fluency tasks were used to measure semantic and phonological retrieval strategies. For the CI group, longitudinal vocabulary and word fluency data (ages 5-15) were obtained from medical records and analyzed using linear mixed models to explore the effects of age and age at implantation. Results: Participants with CI had significantly lower phonological working memory compared to peers with TH but performed similarly on all other measures. Earlier age at implantation was moderately associated with better phonological working memory and metaphor comprehension. Additionally, later- implanted participants relied more on semantic clustering strategies during word retrieval tasks. Associations between both executive functions and vocabulary measures, as well as between metaphor comprehension and relevant control variables, were less widespread in the CI group. Conclusions: Early-implanted adolescents and young adults show cognitive and language outcomes similar to peers with typical hearing. Early auditory access supports higher-level skills, including metaphor comprehension and phonological working memory. Compensatory strategies may support language processing in individuals with cochlear implants, though further research is needed to understand these mechanisms. List of scientific papers I. Löfkvist U, Dahlby-Skoog M, Persson A, Asp F, Verrecchia L, Gripenberg S, Karpeta N, Eklöf M, Karltorp E. Teenagers and Young Adults with Cochlear Implants: A Multidisciplinary Follow-Up Study Approach and Baseline Characteristics. Audiol Res. 2025 Feb 12;15(1):16. https://doi.org/10.3390/audiolres15010016 II. Dahlby-Skoog M, Kalandadze T, Karltorp E, Lyxell B, Löfkvist U. Hearing Early Opens More Doors: Long-Term Effects of Age at Implantation on Metaphor Comprehension in Adolescents and Young Adults with Cochlear Implants. J Speech Lang Hear Res. 2025 Mar 5;68(3):1105-1125. https://doi.org/10.1044/2024_jslhr-24-00480 III. Early Cochlear Implantation Supports Phonological Working Memory in Adolescents and Young Adults with Otherwise Typical Executive Functions. [Manuscript] IV. Lexical Retrieval Strategies and Vocabulary Development in Adolescents with Cochlear Implants. [Manuscript]