# In Middle-Aged Adults, Cognitive Performance Improves After One Year of Auditory Rehabilitation with a Cochlear Implant

## TL;DR

Cochlear implants improve hearing and cognitive skills like memory and processing speed in middle-aged adults with hearing loss.

## Contribution

This study shows cognitive benefits of cochlear implants in middle-aged adults, a group previously understudied in auditory rehabilitation research.

## Key findings

- Working memory and processing speed improved significantly after one year of cochlear implant use.
- Quality of life and tinnitus distress also improved, with stronger correlations between cognitive outcomes and auditory/psychosocial measures post-implant.
- Speech intelligibility and subjective hearing scores increased significantly after the intervention.

## Abstract

Background/Objectives: Hearing impairment in middle-aged adults is a significant, modifiable risk factor for cognitive decline and dementia, and therapy with hearing aids or cochlear implants has been suggested to reduce this risk. However, most research on auditory rehabilitation and cognition has focused on older adults, and evidence regarding cognitive outcomes in middle-aged adults remains scarce despite this group being identified as critical for dementia prevention. Thus, this study aimed to assess cognitive skills in middle-aged hearing-impaired individuals 1 year after receiving a cochlear implant (CI) as part of auditory rehabilitation. Methods: Thirty-two patients with a mean age of 52.4 were enrolled in a prospective pre-post study. Hearing was tested using the Freiburg Monosyllable Test (FS) and the Oldenburg Inventory (OI). Cognitive performance was assessed using the WAIS-IV, operationalized through the Working Memory Index (Digit Span, Arithmetic) and Processing Speed Index (Symbol Search, Coding). Quality of life was assessed with the NCIQ, tinnitus-related distress with the Tinnitus Questionnaire (TQ), and depressive symptoms with the ADS-L. Results: After one year, speech intelligibility (FS) improved from a median of 0 to 70.0 (Wilcoxon Z = −4.864, p < 0.001, r = −0.61), and subjective hearing from a median of 2.55 to 3.18 (Wilcoxon Z = −3.072, p = 0.002). The NCIQ score increased from 52.3 to 60.6 (Z = −3.899, p < 0.001), and tinnitus-related distress decreased from 25 to 21 (Wilcoxon Z = −2.209, p = 0.027). Depressive symptoms declined numerically, although this change did not reach statistical significance. Working memory improved from 82.0 to 89.0 (Wilcoxon Z = −4.090, p < 0.001), and processing speed from 89.5 to 95.5 (Wilcoxon Z = −2.533, p = 0.011). Before CI, WMI and PSI showed a strong correlation (ρ = 0.533, p = 0.002), and WMI correlated moderately with education level (ρ = 0.452, p = 0.012). One year after CI, correlations strengthened between PSI and NCIQ (ρ = 0.510, p = 0.006), PSI and OI (ρ = 0.400, p = 0.039), and WMI and TQ (ρ = –0.459, p = 0.021), indicating emerging associations between cognitive outcomes and auditory or psychosocial measures. Conclusions: One year of CI-based auditory rehabilitation improves auditory function, quality of life, tinnitus distress, and—critically—working memory and processing speed in middle-aged adults. These findings address a previously unfilled research gap and support the relevance of CIs for preserving cognitive health during midlife.