IMPROVEMENT OF COGNITIVE FUNCTION AFTER COCHLEAR IMPLANTATION IN ELDERLY PATIENTS

Large prospective studies have established an independent association between hearing impairment and cognitive decline. Individuals with mild to severe hearing loss have a 2- to 5-fold increased risk of developing dementia compared with those with normal hearing. Moreover, neuroimaging studies report an association between peripheral hearing impairment and temporal lobe cortex and whole brain atrophy. A combination of several interdependent mechanisms could account for this association, such as vascular risk factors, neurodegenerative processes affecting both peripheral auditory pathways and the cerebral cortex, social isolation, and reduced cognitive stimulation. Based on these reports, hearing rehabilitation using conventional hearing aids has logically been proposed as a treatment to help improve neurocognitive performance; however, the impact of the rehabilitation generated controversial results, with a beneficial effect reported in only half of the elderly groups presented in the 6 published analyses.

In cases of acquired severe to profound hearing loss with no benefit from conventional amplification, cochlear implantation that uses direct electrical stimulation of the auditory nerve has proved to be successful; patients 80 years or older are one of the groups receiving benefit.11,12 Retrospective studies13-24 in the geriatric population report improvement for auditory performance in quiet and noise despite prolonged duration of deafness, as well as agerelated degeneration of the spiral ganglion and central auditory pathways. Moreover, similar to younger patients with cochlear implants, most elderly patients who have received implants show an increase in social activities and improved confidence. To the best of our knowledge, the relationship between hearing benefit following cochlear implantation and cognitive abilities in elderly patients has not been investigated.

The objective of this prospective, longitudinal multi center study was to assess speech perception, cognitive abilities, and quality-of-life scores before implantation and at 6 and 12months after cochlear implant activation in patients 65 years or older. The focus was to determine the effect of hearing rehabilitation including the cochlear implant on cognitive function in addition to the influence of cognitive factors on cochlear implantation outcomes over time.

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