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

To conduct critical assessment of the literature on the effects of cochlear implantation on adults’ cognitive abilities.
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.
Out of 1830 studies, 16 met the inclusion criteria.
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%].
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.