Cognitive Functions in Adult Cochlear Implant Users, Cochlear Implant Candidates, and Normal‐Hearing Listeners

Abstract

ObjectivesIncreasing evidence suggests that hearing loss may be linked to cognitive decline, and that cochlear implantation may lead to improvements in cognition. The goal of this study was to examine the effects of severe‐to‐profound hearing loss and cochlear implantation in post‐lingually deafened adults, compared with age‐matched normal‐hearing (NH) peers. Participants were tested on several non‐auditory measures of cognition: working memory (WM) (digit span, object span, symbol span), non‐verbal reasoning (Raven's progressive matrices), information‐processing speed and inhibitory control (Stroop test), speed of phonological and lexical access (Test of Word Reading Efficiency), and verbal learning and memory (California Verbal Learning Test). Demographic measures were also collected.MethodsCohort study at tertiary neurotology center. Forty‐three post‐lingually deafened experienced CI users, 19 post‐lingually deafened CI candidates, and 40 age‐matched NH controls with no cognitive impairment were enrolled. Comparisons among the groups on the cognitive measures were performed.ResultsAdult CI users and CI candidates demonstrated worse (or a trend towards worse) performance as compared with NH peers on non‐verbal reasoning, information‐processing speed, speed of lexical access, and verbal learning and memory. However, after controlling for gender, socioeconomic status (SES), and vocabulary knowledge among groups, some of these differences were no longer significant. Similarly, large differences were not found in most cognitive abilities between experienced CI users and CI candidates.ConclusionsAdult CI users, CI candidates, and NH peers generally demonstrated equivalent non‐auditory cognitive abilities, after controlling for gender, SES, and vocabulary knowledge. These findings provide support for a link between cognitive decline and hearing loss, but this association may be partly attributable to group differences in SES and vocabulary knowledge.Level of Evidence2b.

High- and Low-Performing Adult Cochlear Implant Users on High-Variability Sentence Recognition: Differences in Auditory Spectral Resolution and Neurocognitive Functioning

“…However, note that because the focus of the present study was to determine whether auditory spectral resolution and neurocognitive functioning discriminate high-and low-performers on the PRESTO rather than to explain individual differences, scores from neurocognitive tests were not adjusted by demographic factors, such as age, SES, and gender, for the analyses. Given possible associations between demographic factors and cognitive skills (e.g., Kramer et al) 25 , some of the differences between groups could be attributed to these factors. Moreover, had normalized scores been used, the discriminant function may have had a weaker discriminating ability.…”

“…Data from 21 postlingually deafened adult CI users were included in the present study. All of the CI users had participated in a larger study on speech, language, and neurocognitive skills, which, at the time of the present study, included 44 adult postlingually deafened CI users (Moberly et al; 33 Kramer et al; 25 Moberly et al). 35 Of the 21 CI users in the present study, 11 scored within the upper quartile of the distribution (HiPRESTO) and 10 scored within the lower quartile (LoPRESTO) of a group of 44 CI users (overlapping with participant groups reported in earlier studies) on PRESTO, after adjusting for those who did not complete or were unable to complete the SMRT (n ¼ 4).…”

“…Measures used in the present study are described in the following paragraphs. For detailed information on the general approach, materials, and collection procedures, see Moberly et al (2017), 33 Kramer et al (2018), 25 and Moberly et al (2018). 35…”

“…Some specific neurocognitive skills, such as working memory capacity, appear to be more strongly related to speech perception and recognition and may be more strongly related than more general cognitive abilities, such as nonverbal intelligence (for a review, see Akeroyd) 1 . Working memory (Lyxell et al; 29 Tao et al) 52 as well as inhibitory control (Moberly et al 31 ), verbal learning and memory (Pisoni et al) 25 , and processing speed (Tinnemore et al) 53 have been linked to individual differences in speech recognition among adult CI users. In addition, although a strong relation has not been established, nonverbal reasoning skills have recently been found to be associated with individual performance among postlingually deafened adult CI users, independently of age (Mattingly et al) 30 .…”

Prognostics Factors of Cochlear Implant in Adults: How Can We Improve Poorer Performers?

“…Thus, a profound aim of active rehabilitation is to take advantage, and encourage, reverse plasticity to aid in restoring cortical preference to meaningful auditory signals. This need is also recognized by other authors [27].…”