Can Cochlear Implantation in Older Adults Reverse Cognitive Decline Due to Hearing Loss?

COCHLEA: Longitudinal Cognitive Performance of Older Adults with Hearing Loss and Cochlear Implants at 4.5-Year Follow-Up

OBJECTIVES

Hearing loss is highly prevalent in older adults and is independently associated with accelerated cognitive decline. Cochlear implants are usually the only effective treatment for people with severe-profound hearing loss, who have the highest risk of cognitive decline and dementia, however, very few receive them. Current evidence of the effects of cochlear implant use on cognitive decline/dementia outcomes is limited and unclear. This study aimed to investigate the effect of cochlear implant use on longitudinal cognitive performance, as this intervention may be an effective method of modifying cognitive outcomes for older adults with significant hearing loss.

METHODS

This prospective longitudinal observational study investigated cognitive performance in a convenience sample of older adults (mean age 74 years) with cochlear implants over 4.5 years post-implantation, comparing this with that of community-living adults with untreated hearing loss/normal hearing over 3 years (Australian Imaging, Biomarker and Lifestyle Flagship Study of Ageing; AIBL). All participants were assessed at 18-month intervals from baseline using the same measures. Panel regression was used to compare cognitive trajectories.

RESULTS

Cochlear implant users demonstrated significantly improved performance in executive function and working memory, as well as stability in attention, psychomotor function, and visual learning at 4.5-year follow-up. Comparatively, AIBL participants showed significantly greater worsening performance per year in attention and psychomotor function, and stability in working memory and visual learning at 3-year follow-up.

CONCLUSIONS

Cochlear implant use may delay cognitive decline and/or improve cognitive performance in older adults with severe-profound hearing loss, providing proof-of-concept evidence of the positive effects of hearing intervention on cognitive performance in older adults with hearing loss.

A Scoping Review and Meta-Analysis of the Relations Between Cognition and Cochlear Implant Outcomes and the Effect of Quiet Versus Noise Testing Conditions

OBJECTIVES

Evidence continues to emerge of associations between cochlear implant (CI) outcomes and cognitive functions in postlingually deafened adults. While there are multiple factors that appear to affect these associations, the impact of speech recognition background testing conditions (i.e., in quiet versus noise) has not been systematically explored. The two aims of this study were to (1) identify associations between speech recognition following cochlear implantation and performance on cognitive tasks, and to (2) investigate the impact of speech testing in quiet versus noise on these associations. Ultimately, we want to understand the conditions that impact this complex relationship between CI outcomes and cognition.

DESIGN

A scoping review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed on published literature evaluating the relation between outcomes of cochlear implantation and cognition. The current review evaluates 39 papers that reported associations between over 30 cognitive assessments and speech recognition tests in adult patients with CIs. Six cognitive domains were evaluated: Global Cognition, Inhibition-Concentration, Memory and Learning, Controlled Fluency, Verbal Fluency, and Visuospatial Organization. Meta-analysis was conducted on three cognitive assessments among 12 studies to evaluate relations with speech recognition outcomes. Subgroup analyses were performed to identify whether speech recognition testing in quiet versus in background noise impacted its association with cognitive performance.

RESULTS

Significant associations between cognition and speech recognition in a background of quiet or noise were found in 69% of studies. Tests of Global Cognition and Inhibition-Concentration skills resulted in the highest overall frequency of significant associations with speech recognition (45% and 57%, respectively). Despite the modest proportion of significant associations reported, pooling effect sizes across samples through meta-analysis revealed a moderate positive correlation between tests of Global Cognition ( r = +0.37, p < 0.01) as well as Verbal Fluency ( r = +0.44, p < 0.01) and postoperative speech recognition skills. Tests of Memory and Learning are most frequently utilized in the setting of CI (in 26 of 39 included studies), yet meta-analysis revealed nonsignificant associations with speech recognition performance in a background of quiet ( r = +0.30, p = 0.18), and noise ( r = -0.06, p = 0.78).

CONCLUSIONS

Background conditions of speech recognition testing may influence the relation between speech recognition outcomes and cognition. The magnitude of this effect of testing conditions on this relationship appears to vary depending on the cognitive construct being assessed. Overall, Global Cognition and Inhibition-Concentration skills are potentially useful in explaining speech recognition skills following cochlear implantation. Future work should continue to evaluate these relations to appropriately unify cognitive testing opportunities in the setting of cochlear implantation.

Cognitive processing speed improvement after cochlear implantation

Background

Untreated hearing loss has an effect on cognition. It is hypothesized that the additional processing required to compensate for the sensory loss affects the cognitive resources available for other tasks and that this could be mitigated by a hearing device.

Methods

The impact on cognition of cochlear implants (CIs) was tested in 100 subjects, ≥60 years old, with bilateral moderately-severe to profound post linguistic deafness using hearing aids. Data was compared pre and 12 and 18 months after cochlear implantation for the speech spatial qualities questionnaire, Mini Mental State Examination (MMSE), Trail making test B (TMTB) and digit symbol coding (DSC) from the Wechsler Adult Intelligence Scale version IV and finally the timed up and go test (TUG). Subjects were divided into young old (60-64), middle old (65-75) and old old (75+) groups. Cognitive test scores and times were standardized according to available normative data.

Results

Hearing significantly improved pre- to post-operatively across all age groups. There was no change post-implant in outcomes for TMTB, TUG or MMSE tests. Age-corrected values were within normal expectations for all age groups for the TUG and MMSE. However, DSC scores and TMTB times were worse than normal. There was a significant increase in DSC scores between baseline and 12-months for 60- to 64-year-olds (t[153] = 2.608, p = 0.027), which remained at 18 months (t[153] = 2.663, p = 0.023).

Discussion

The improved attention and processing speed in the youngest age group may be a consequence of reallocation of cognitive resources away from auditory processing due to greatly improved hearing. The oldest age group of participants had cognition scores closest to normal values, suggesting that only the most able older seniors tend to come forward for a CI. Severe to profoundly deaf individuals with hearing aids or cochlear implants were still poorer than age-equivalent normally hearing individuals with respect to cognitive flexibility, attention, working memory, processing speed and visuoperceptual functions. Due to a lack of data for the TUG, TMTB and DSC in the literature for hearing impaired individuals, the results reported here provide an important set of reference data for use in future research.

Emerging Relations among Cognitive Constructs and Cochlear Implant Outcomes: A Systematic Review and Meta-Analysis

OBJECTIVE

Hearing loss has a detrimental impact on cognitive function. However, there is a lack of consensus on the impact of cochlear implants on cognition. This review systematically evaluates whether cochlear implants in adult patients lead to cognitive improvements and investigates the relations of cognition with speech recognition outcomes.

DATA SOURCES

A literature review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies evaluating cognition and cochlear implant outcomes in postlingual, adult patients from January 1996 to December 2021 were included. Of 2510 total references, 52 studies were included in qualitative analysis and 11 in meta-analyses.

REVIEW METHODS

Proportions were extracted from studies of (1) the significant impacts of cochlear implantation on 6 cognitive domains and (2) associations between cognition and speech recognition outcomes. Meta-analyses were performed using random effects models on mean differences between pre- and postoperative performance on 4 cognitive assessments.

RESULTS

Only half of the outcomes reported suggested cochlear implantation had a significant impact on cognition (50.8%), with the highest proportion in assessments of memory & learning and inhibition-concentration. Meta-analyses revealed significant improvements in global cognition and inhibition-concentration. Finally, 40.4% of associations between cognition and speech recognition outcomes were significant.

CONCLUSION

Findings relating to cochlear implantation and cognition vary depending on the cognitive domain assessed and the study goal. Nonetheless, assessments of memory & learning, global cognition, and inhibition-concentration may represent tools to assess cognitive benefit after implantation and help explain variability in speech recognition outcomes. Enhanced selectivity in assessments of cognition is needed for clinical applicability.

Longitudinal trajectories of memory among middle-aged and older people with hearing loss: the influence of cochlear implant use on cognitive functioning

Introduction

Cochlear implants (CI) are the gold standard intervention for severe to profound hearing loss, a known modifiable risk factor for dementia. However, it remains unknown whether CI use might prevent the age-related cognitive decline. Recent studies are encouraging but are limited, mainly by short follow-up periods and, for ethical reasons, lack of appropriate control groups. Further, as age-related cognitive decline is multifaceted and not linear, other statistical approaches have to be evaluated.

Materials and methods

Immediate and delayed recall as measures of cognitive function were assessed in 75 newly implanted CI users (mean age 65.41 years ± 9.19) for up to 5 years (mean 4.5 ± 0.5) of CI use and compared to 8,077 subjects of the same age range from two longitudinal cohort studies, the Health and Retirement Study (HRS) and the English Longitudinal Study of Aging (ELSA). Linear and quadratic changes in cognitive trajectories were analyzed in detail using mixed growth models, considering possible confounders.

Results

For CI users, the linear time slope showed a significant improvement in the specific domains (recall and delayed recall) over time. The quadratic time slope clearly indicated that the predicted change after CI provision followed an inverted U-shape with a predicted decline 2 years after CI provision. In the hearing-impaired group, a significant decline over time was found, with steeper declines early on and the tendency to flatten out in the follow-up.

Conclusion

Cochlear implant use seems to boost cognitive trajectories in the first years after implantation. However, long-term prevention of dementia seems to need far more than restoration of hearing loss.

Effects of cochlear implantation on cognitive decline in older adults: A systematic review and meta-analysis

Background

Hearing loss has been reported as the most significant modifiable risk factor for dementia, but it is still unknown whether auditory rehabilitation can practically prevent cognitive decline. We aim to systematically analyze the longitudinal effects of auditory rehabilitation via cochlear implants (CIs).

Methods

In this systematic review and meta-analysis, we searched relevant literature published from January 1, 2000 to April 30, 2022, using electronic databases, and selected studies in which CIs were performed mainly on older adults and follow-up assessments were conducted in both domains: speech perception and cognitive function. A random-effects meta-analysis was conducted for each domain and for each timepoint comparison (pre-CI vs. six months post-CI; six months post-CI vs. 12 months post-CI; pre-CI vs. 12 months post-CI), and heterogeneity was assessed using Cochran's Q test.

Findings

Of the 1918 retrieved articles, 20 research papers (648 CI subjects) were included. The results demonstrated that speech perception was rapidly enhanced after CI, whereas cognitive function had different speeds of improvement for different subtypes: executive function steadily improved significantly up to 12 months post-CI (g = 0.281, p < 0.001; g = 0.115, p = 0.003; g = 0.260, p < 0.001 in the order of timepoint comparison); verbal memory was significantly enhanced at six months post-CI and was maintained until 12 months post-CI (g = 0.296, p = 0.002; g = 0.095, p = 0.427; g = 0.401, p < 0.001); non-verbal memory showed no considerable progress at six months post-CI, but significant improvement at 12 months post-CI (g = -0.053, p = 0.723; g = 0.112, p = 0.089; g = 0.214, p = 0.023).

Interpretation

The outcomes demonstrate that auditory rehabilitation via CIs could have a long-term positive impact on cognitive abilities. Given that older adults' cognitive abilities are on the trajectory of progressive decline with age, these results highlight the need to increase the adoption of CIs among this population.

Cochlear implants: the effects of age on outcomes

INTRODUCTION

Cochlear implants (CIs) provide access to sound for children and adults who do not receive adequate benefit from hearing aids. Age at implantation is known to affect outcomes across the lifespan.

AREAS COVERED

The effects of age on CI outcomes are examined for infants, children, adolescents, and older adults. A variety of outcome measures are considered, including speech perception, language, cognition, and quality of life measures.

EXPERT OPINION/COMMENTARY

For those meeting candidacy criteria, CIs are beneficial at any age. In general, younger age is related to greater benefit when considering pre-lingual deafness. Other factors such as additional disabilities, may mitigate this effect. Post-lingually deafened adults demonstrate similar benefit regardless of age, though the oldest individuals (80+) may see smaller degrees of improvement from preoperative scores. Benefit can be measured in many ways, and the areas of greatest benefit may vary based on age: young children appear to see the greatest effects of age at implantation on language measures, whereas scores on cognitive measures appear to be most impacted for the oldest population. Future research should consider implantation at extreme ages (5-9 months or > 90 years), unconventional measures of CI benefit including qualitative assessments, and longitudinal designs.

Hearing loss and its link to cognitive impairment and dementia

Hearing loss is an important risk factor for the development of dementia, particularly Alzheimer's disease (AD). Mid-life hearing loss increases the risk of developing dementia by double any other single factor. However, given this strong connection between hearing loss and AD, the mechanisms responsible for this link are still unknown. Data from observational studies relating hearing loss and cognitive impairment, measured with standardized questionnaires, has shown a strong relationship between them. Similar findings have emerged from animal studies, showing that the induction of hearing loss via prolonged loud sound exposure or ear canal blocking, can impair cognitive abilities. Interestingly, patients with age-related hearing impairment exhibit increased phosphorylated tau in the cerebrospinal fluid, but no such relationship has been identified for amyloid-β. In addition, hearing loss predisposes to social isolation precipitating the development of dementia through a supposed reduction in cognitive load and processing requirements. Given this link between hearing loss and dementia, the question arises whether the restoration of hearing might mitigate against the onset or progress of AD. Indeed, there is a growing body of research that suggests that those who wear hearing aids for age-related hearing problems maintain better cognitive function over time than those who do not. These are compelling findings, as they suggest the use of hearing aids has the potential to be a cost-effective treatment for those with hearing loss both prior (for those at high risk for AD) and after the development of symptoms. This review aims to summarize the current theories that relate hearing loss and cognitive decline, present the key findings of animal studies, observational studies and summarize the gaps and limitations that need to be addressed in this topic. Through this, we suggest directions for future studies to tackle the lack of adequately randomized control trials in the field. This omission is responsible for the inability to provide a conclusive verdict on whether to use hearing interventions to target hearing-loss related cognitive decline.

Listening with an Ageing Brain - a Cognitive Challenge

Hearing impairment has been recently identified as a major modifiable risk factor for cognitive decline in later life and has been becoming of increasing scientific interest. Sensory and cognitive decline are connected by complex bottom-up and top-down processes, a sharp distinction between sensation, perception, and cognition is impossible. This review provides a comprehensive overview on the effects of healthy and pathological aging on auditory as well as cognitive functioning on speech perception and comprehension, as well as specific auditory deficits in the 2 most common neurodegenerative diseases in old age: Alzheimer disease and Parkinson syndrome. Hypotheses linking hearing loss to cognitive decline are discussed, and current knowledge on the effect of hearing rehabilitation on cognitive functioning is presented. This article provides an overview of the complex relationship between hearing and cognition in old age.

Age effects on cognitive functions and speech-in-noise processing: An event-related potential study with cochlear-implant users and normal-hearing listeners

A cochlear implant (CI) can partially restore hearing in individuals with profound sensorineural hearing loss. However, electrical hearing with a CI is limited and highly variable. The current study aimed to better understand the different factors contributing to this variability by examining how age affects cognitive functions and cortical speech processing in CI users. Electroencephalography (EEG) was applied while two groups of CI users (young and elderly; N = 13 each) and normal-hearing (NH) listeners (young and elderly; N = 13 each) performed an auditory sentence categorization task, including semantically correct and incorrect sentences presented either with or without background noise. Event-related potentials (ERPs) representing earlier, sensory-driven processes (N1-P2 complex to sentence onset) and later, cognitive-linguistic integration processes (N400 to semantically correct/incorrect sentence-final words) were compared between the different groups and speech conditions. The results revealed reduced amplitudes and prolonged latencies of auditory ERPs in CI users compared to NH listeners, both at earlier (N1, P2) and later processing stages (N400 effect). In addition to this hearing-group effect, CI users and NH listeners showed a comparable background-noise effect, as indicated by reduced hit rates and reduced (P2) and delayed (N1/P2) ERPs in conditions with background noise. Moreover, we observed an age effect in CI users and NH listeners, with young individuals showing improved specific cognitive functions (working memory capacity, cognitive flexibility and verbal learning/retrieval), reduced latencies (N1/P2), decreased N1 amplitudes and an increased N400 effect when compared to the elderly. In sum, our findings extend previous research by showing that the CI users' speech processing is impaired not only at earlier (sensory) but also at later (semantic integration) processing stages, both in conditions with and without background noise. Using objective ERP measures, our study provides further evidence of strong age effects on cortical speech processing, which can be observed in both the NH listeners and the CI users. We conclude that elderly individuals require more effortful processing at sensory stages of speech processing, which however seems to be at the cost of the limited resources available for the later semantic integration processes.

Can cochlear implantation prevent cognitive decline in the long-term follow-up?

Cognitive function and hearing are known to both decline in older adults. As hearing loss is proposed to be one modifiable risk factor for dementia, the impact of auditory rehabilitation on cognitive decline has been gaining increasing attention. Despite a large number of studies, long-term data are still rare. In a large prospective longitudinal monocentric study, 50 adults (aged ≥ 50 years) with severe postlingual bilateral hearing loss received a cochlear implant (CI). They underwent comprehensive neurocognitive testing prior to implantation (T1), at 12 months (T2) and up to 65 months (T3) after implantation. Various cognitive subdomains such as attention, inhibition, working memory, verbal fluency, mental flexibility and (delayed) recall were assessed by the computer-based non-auditory test battery ALAcog©. The observed trajectories of two exemplary cognitive subdomains (delayed recall and working memory) were then fitted over time using multilevel growth models to adjust for sociodemographic covariates and compared with 5-year longitudinal data from a sample of older adults from the representative Survey of Health, Aging and Retirement in Europe (SHARE) study. Postoperatively, auditory functions improved from 6.98% (SD 12.83) to 57.29% (SD 20.18) in monosyllabic speech understanding. Cognitive functions significantly increased from T1 to T3 in attention (p = 0.001), delayed recall (p = 0.001), working memory (OSPAN; p = 0.001), verbal fluency (p = 0.004), and inhibition (p = 0.002). A closer look at follow-up revealed that cognitive improvement could be detected between T1 and T2 and thereafter remained stable in all subtests (p ≥ 0.06). Additional longitudinal analysis confirmed these findings in a rigorous multilevel approach in two exemplary cognitive subdomains. In contrast to the SHARE data, there was no evidence for age-differential associations over time in CI recipients. This suggests that older adults benefit equally from cochlear implantation. CI users with worse preoperative cognitive skills experienced the most benefit (p < 0.0001). Auditory rehabilitation by cochlear implantation has a stimulating effect on cognitive functions beyond an improvement in speech understanding and an increased well-being. Large multicenter studies using standardized protocols have to be undertaken in the future to find out whether hearing restoration might help to prevent cognitive decline.

Do Not Go Gentle into That Deaf Night: A Holistic Perspective on Cochlear Implant Use as Part of Healthy Aging

Research suggests that cochlear implant (CI) use in elderly people improves speech perception and health-related quality of life (HRQOL). CI provision could also prevent dementia and other comorbidities and support healthy aging. The aim of this study was (1) to prospectively investigate potential changes in HRQOL and speech perception and (2) to identify clinical action points to improve CI treatment. Participants (n = 45) were CI recipients aged 60-90 with postlingual deafness. They were divided into groups, according to age: Group 1 (n = 20) received a CI between the age of 60-70 years; group 2 (n = 25) between the age of 71-90 years. HRQOL and speech perception were assessed preoperatively, and three and twelve months postoperatively. HRQOL and speech perception increased significantly within one year postoperatively in both groups. No difference between groups was found. We conclude that CI treatment improves speech perception and HRQOL in elderly users. Improvement of the referral process for CI treatment and a holistic approach when discussing CI treatment in the elderly population could prevent auditory deprivation and the deterioration of cognitive abilities.

Cognitive and behavioral effects of hearing loss

PURPOSE OF REVIEW

Hearing loss is one of the largest modifiable risk factors for developing dementia, accounting for up to 9% of the overall modifiable risk. The neuropsychologic and psychosocial impacts of hearing loss are becoming increasingly appreciated. The objective of this review is to explore the recent literature regarding the cognitive and behavioral effects of hearing loss and the role of hearing rehabilitation, particularly in older adults.

RECENT FINDINGS

Cognitive decline may begin while patients have subclinical hearing loss, earlier than previously thought. Hearing rehabilitation, either via hearing amplification, middle ear surgery, or cochlear implantation, likely plays a role in preventing or slowing the rate of cognitive decline in patients with hearing loss. Hearing loss can increase the likelihood of social isolation, loneliness and depression in older adults, but it is unclear at this time what effect hearing rehabilitation has on these domains.

SUMMARY

Hearing loss is one of the largest modifiable risk factors for cognitive decline, and hearing rehabilitation can play a significant role in preserving cognitive function. Understanding the cognitive and psychosocial impact of hearing loss can help facilitate the development of approaches for prevention and treatment.

Cochlear Implantation in Hearing-Impaired Elderly: Clinical Challenges and Opportunities to Optimize Outcome

Cochlear implant (CI) overall provides a very good outcome, but speech comprehension outcome in the elderly is more variable. Several clinical factors play an important role. The management of residual hearing, the presence of comorbidities, and especially the progression of cognitive decline seem to be the clinical parameters that strongly determine the outcome of cochlear implantation and need to be discussed prospectively in the consultation process with the elderly hearing impaired. In the context of this review article, strategies for dealing with these will be discussed. Timely cochlear implantation should already be considered by hearing aid acousticians or practicing otolaryngologists and communicated or initiated with the patient. This requires intensive cooperation between hearing aid acousticians and experts in the clinic. In addition, residual hearing and comorbidities in the elderly need to be considered to make realistic predictions about speech comprehension with CI. Long-term aftercare and its different implementations should be discussed preoperatively, so that the elderly person with hearing impairments feels well taken care of together with his or her relatives. Elderly patients with hearing impairments benefit most from a CI in terms of speech comprehension if there is a large cochlear coverage (electrical or acoustic electrical) and the therapy is not hampered by comorbidities, especially cognitive decline.

Changes in cognitive performance after cochlear implantation in adults and older adults: a systematic review and meta-analysis

OBJECTIVES

To conduct critical assessment of the literature on the effects of cochlear implantation on adults' cognitive abilities.

DESIGN

PubMed, Scopus, Lilacs, Web of Science, Livivo, Cochrane, Embase, PsycInfo, and grey literature were searched. Eligibility criteria: age 18 or over with severe-to-profound bilateral hearing loss, cochlear implantation, cognitive test before and after implantation. Risk of bias was assessed using ROB, ROBINS-I and MASTARI tools. Meta-analysis was performed.

STUDY SAMPLE

Out of 1830 studies, 16 met the inclusion criteria.

RESULTS

On AlaCog test, significant improvement was found after implantation [MD = -46.64; CI95% = -69.96 to -23.33; I² = 71%]. No significant differences were found on the Flanker, Recall, Trail A and n-back tests (p > 0.05). For MMSE, no significance was found [MD 0.63; CI 95% = -2.19 to 3.45; I² = 88%]. On TMT, an overall significant effect with a 9-second decrease in processing speed post-implantation [MD = -9.43; CI95% = -15.42 to -3.44; I² = 0%].

CONCLUSION

Cognitive improvements after cochlear implantation may depend on time and the cognitive task evaluated. Well-designed studies with longer follow-up are necessary to examine whether cochlear implantation has a positive influence on cognitive abilities. Development of cognitive assessment tools to hearing-impaired individuals is needed.

Cognition and Cognitive Reserve in Cochlear Implant Recipients

At present, dementia is a hot topic. Hearing loss is considered to be a modifiable risk factor for cognitive decline. The underlying mechanism remains unclear and might be mediated by socioeconomic and psychosocial factors. Cochlear implantation has been shown not only to restore auditory abilities, but also to decrease mental distress and to improve cognitive functions in people with severe hearing impairment. However, the promising results need to be confirmed. In a prospective single-center study, we tested the neurocognitive abilities of a large group of 71 subjects with bilateral severe hearing impairment with a mean age of 66.03 (SD = 9.15) preoperatively and 6, 12, and 24 months after cochlear implantation using a comprehensive non-auditory computer-based test battery, and we also assessed the cognitive reserve (CR) [Cognitive Reserve Index (CRI)], health-related quality of life (QoL) (Nijmegen Cochlear Implant Questionnaire), and depression (Geriatric Depression Scale-15). Cognitive functions significantly increased after 6 months in attention (p = 0.00004), working memory (operation span task; p = 0.002), and inhibition (p = 0.0002); and after 12 months in recall (p = 0.003) and verbal fluency (p = 0.0048), and remained stable up to 24 months (p ≥ 0.06). The CR positively correlated with cognitive functions pre- and post-operatively (both p < 0.005), but postoperative improvement in cognition was better in subjects with poor CR (p = 0.003). Depression had only a slight influence on one subtest. No correlation was found among cognitive skills, quality of life, and speech perception (each p ≥ 0.05). Cochlear implantation creates an enriched environment stimulating the plasticity of the brain with a global positive impact on neurocognitive functions, especially in subjects with poor preoperative cognitive performance and low cognitive reserve.