The Effect of Cochlear Implants on Cognitive Function in Older Adults: Initial Baseline and 18-Month Follow Up Results for a Prospective International Longitudinal Study

Abstract

In older adults, hearing loss is independently associated with an increased rate of cognitive decline, and has been identified to be a modifiable risk factor for dementia. The mechanism underlying the cognitive decline associated with hearing loss is not understood, but it is known that the greater the hearing loss, the faster the rate of decline. It is unknown whether remediation of hearing loss with hearing devices can delay cognitive decline. This 5-year international longitudinal study is investigating the impact of cochlear implants on cognitive function in older people with severe-profound hearing loss, and whether remediation of hearing loss could delay the onset of cognitive impairment. This is the first study to examine the major primary risk factors associated with dementia in the same cohort. Participants were assessed before cochlear implantation and 18 months later using an identical battery including a visually presented cognitive assessment tool (Cogstate battery) that is highly sensitive to small changes in cognition and suitable for use with people with hearing loss. Hearing and speech perception ability were assessed in sound-treated conditions by an audiologist, and a range of questionnaire tools was administered to assess self-perceived ease of listening, quality of life, physical activity, diet, social and emotional loneliness, isolation, anxiety, and depression. A detailed medical health history was taken. Pre-operatively, despite the small initial sample size ( n = 59), increased hearing loss and age predicted significantly poorer executive function and visual attention, while tertiary education predicted better executive function. Better self-reported quality of life was correlated with better visual learning performance, and engaging in frequent vigorous physical activity was correlated with poorer visual learning performance. At 18 months, for the first 20 participants, significant benefits of cochlear implants were seen in terms of speech perception, communication ability, and quality of life. Multiple linear regression modeling showed executive function improved significantly for non-tertiary educated males, while cognitive function remained stable for other participants. Further follow-up at 18 month intervals with a larger sample will reveal the effects of cochlear implant intervention on all outcomes, and whether this can delay cognitive decline.

The Effect of Hearing Aid Use on Cognition in Older Adults: Can We Delay Decline or Even Improve Cognitive Function?

“…As summarized in recent systematic reviews [12,14], a negative relationship between age-related hearing loss and cognitive function has now been widely reported in many studies, with significantly poorer executive function in particular associated with hearing loss in some studies [15,48,49].…”

Does Treating Hearing Loss in Older Adults Improve Cognitive Outcomes? A Review

“…After the publication of these two reviews, a clinical study examined the effect on cognition of cochlear implantation on 59 adults aged 61-89 years with severe-profound hearing loss and no previously diagnosed or suspected cognitive impairment [71]. At 18 months, significant benefits of cochlear implants were observed in terms of speech perception, communication ability, and quality of life.…”

Healthy aging in elderly cochlear implant recipients: a multinational observational study

“…The most common path to remediating hearing loss is through evaluations that may lead to the use of hearing aids (HA). However, in cases where HL cannot be compensated by hearing aids, cochlear implant (CI) may be a viable option [63]; however, due to financial constraints, CIs may not always be available. Thus, already in 2017, in a report called Action for Hearing Loss, WHO urged international investment in the identification and treatment of HL enabling improved access to cochlear implants, among other auditory enhancement technologies [74].…”

“…With respect to benefits from cochlear implantation, strong supporting evidence suggests that an improvement in functional hearing status via the use of cochlear implants in older adults has far-reaching effects on hearing-related quality of life and other health-related domains. Earlier studies (2002–2009) were most interested in psychosocial factors such as depression and isolation [ 22 , 51 , 57 , 72 ]; whereas, most of the later studies (2015–2019) began investigating effects on cognition [ 5 , 9 , 12 , 14 , 47 – 49 , 62 , 63 , 66 , 73 ]. Routine clinical follow up shows a trend for added benefits of CI treatment upon dependency, mobility and the risk of falls [ 35 ].…”

“…The current study, to our knowledge, is the only international prospective investigation currently researching the primary impact on quality of life of cochlear implantation. A similar study underway in Australia [ 63 ], aiming for 5-year follow up, has the primary goal of examining cognitive change associated with CI rehabilitation and utilizes a very different test battery with only two evaluation tools in common. The first report on outcomes confirms benefit in all areas for an initial cohort of 20 CI users with 18 month’s listening experience.…”