Verbal fluency after cochlear implantation: a longitudinal comparison with untreated hearing loss in the ELSA cohort

Hearing loss is associated with accelerated cognitive decline, and auditory rehabilitation via cochlear implantation (CI) may mitigate this trajectory. In the past, the impact of cochlear implantation on different cognitive subdomains has been described. However, verbal fluency (VF), which requires fast semantic retrieval, executive control, and processing speed, and is predictive of dementia risk and overall survival, has been rarely studied and control groups are mostly missing due to ethical reasons. The present study compares long-term VF trajectories in CI recipients and untreated hearing-impaired controls from a large population-based aging study.

VF was assessed in 74 CI recipients (M = 65.6 years, SD = 9.1) at pre-operative baseline and 1, 2, 4.5, and up to 9 years post-implantation, and in 383 untreated hearing-impaired participants (M = 72.6 years, SD = 10.0) from the English Longitudinal Study of Ageing (ELSA) across a comparable time frame. Scores were z-standardized within each study to enable cross-cohort comparison. Linear mixed-effects models were used to compare VF trajectories, with age, sex, and education as covariates.

VF trajectories differed significantly between groups (Time × Study interaction: b = 0.562, p < 0.001). The ELSA cohort showed a steady linear decline over time (b = -0.261, p = 0.001), whereas the CI cohort exhibited an inverted-U trajectory with initial improvement followed by a plateau. After propensity score matching, results remained robust.

Cochlear implantation is associated with more favorable long-term verbal fluency trajectories compared to untreated hearing loss. These findings add to the growing evidence that auditory rehabilitation may help preserve cognitive function in older adults.