The effect of cochlear implants on cognitive function in older adults: A prospective, longitudinal 2-year follow-up study

Objectives: It is shown that eliminating hearing loss in mid-life may reduce the risk for deterioration in cognitive function. Cochlear implantation (CI) is the only available therapy that can eliminate hearing loss in patients who suffer from profound sensorineural hearing loss. This suggests there may be positive effects of hearing level on cognition in older adults following CI. Therefore, the purpose of this study is to clarify whether cognitive function can be improved or maintained using cochlear implants in older adult patients with hearing impairments. Methods: Data for patients that underwent CI surgery for profound bilateral sensorineural hearing loss were collected prospectively. Patients aged 65 years and older were recruited at our university hospital from 2013 to 2017. Twenty-one patients (age range: 65-80 years) were included in this study. The primary outcome measurement was the change in cognitive function three points assessed by Mini-Mental State Examination (MMSE): preoperatively, and at 1 and 2 years after surgery. The secondary outcome measurements were the followings; the Nijmegen Cochlear Implant Questionnaire (NCIQ), the Self-Rating Depression Scale (SDS), and hearing and speech recognition threshold assessment before CI, and 1 and 2 years after CI. Differences in MMSE scores were compared for statistical significance using the Friedman test. The Wilcoxon signed-rank test was used as a post hoc test. Possible correlations between MMSE scores and NCIQ subdomain scores 2 years after surgery were evaluated with Spearman's tests. Statistical significance was defined as a p-value < 0.05. Results: CI recipients showed significant improvement in MMSE scores. This improvement peaked 1 year after CI surgery. The postoperative MMSE score was correlated with the NCIQ