Objectives: To critically assess the status of the literature on cognitive outcomes after cochlear implantation in adults and older adults.

Design and methods: Studies were identified by searching PubMed/Medline, Scopus, Lilacs, Web of Science, Livivo, Cochrane Library, Embase, Psycinfo, and gray literature. No restrictions were imposed regarding language, publication date, or publication status. The studies design included were randomized clinical trials, non-randomized clinical trials, quasi-experimental and cohort studies. Eligibility criteria were as follows: (1) the study sample included adults aged 18 or over with severe to profound bilateral hearing loss, (2) the participants received a multi-electrode cochlear implant, and (3) a cognitive test was performed before and after implantation. Risk of bias was assessed using the ROB, ROBINS-I and MASTARI tools (Joana Briggs Institute), depending on the type of study. Meta-analyses of random effects were performed for the outcomes of interest. The level of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

Study sample: Out of 1830 retrieved records, 16 were found eligible (11 non-randomized clinical trials, 3 randomized clinical trials and 2 cohort studies).

Results: In the AlaCog test, with the overall effect improvement after 6–12 months postoperatively [MD=−46.64; 95% CI=−69.96 – −23.33; I2=71%]. Although the global effect demonstrates statistical significance, the Flanker, Recall, Trail A and n-back test domains did not show statistical significance (p>0.05). For the MMSE, a subgroup analysis was performed, based on postoperative time, but there was no statistical significance in any of the times evaluated [MD 0.63; 95% CI=−2.19 – 3.45; I2=88%]. For the TMT test, the analysis was subdivided based on the postoperative period, presenting a significant global effect, with a decrease of approximately 9s in the processing speed in the postoperative period [MD=−9.43; 95% CI=−15.42 – −3.44; I2=0%].

Conclusion: Hearing loss rehabilitation with cochlear implants may provide positive impacts on cognitive domains. Well-designed studies with longer follow-up periods are necessary to verify whether cochlear implantation influences cognition positively in older adults along the time. Development of new cognitive assessment tools in hearing-impaired individuals is stimulated.

Keywords: Cochlear implantation; Cognition; Older adults; Adults; Systematic review; Cognitive outcomes; Cognitive assessment; Profound hearing loss; Cochlear implant.