Decreased Depression 12 Months After Cochlear Implantation Is Not Associated With Improved Cognitive Performance

Adults with bilateral late-onset hearing loss are at risk for depression and altered cognitive performance. We were interested in whether an improvement in hearing after cochlear implantation (CI) was associated with changes in depression and cognitive performance and whether these changes were related. We hypothesized that 12 mo after CI, hearing ability (speech recognition and subjective hearing) and cognitive performance would improve, and depression would decrease compared with pre-CI status. Furthermore, we hypothesized a negative association between changes in depression and changes in cognition, such that subjects with a higher reduction in depression would show a higher improvement in cognition. We also investigated whether changes in hearing, depression, and cognition differed between younger (<60 yr old) and older CI users (≥60 yr old).

This cohort study took place at two tertiary referral centers. We recruited participants aged 25 to 75 during outpatient and inpatient care. Our inclusion criteria comprised an onset of hearing loss in adulthood (over 18 yr), severe to profound symmetrical bilateral sensorineural hearing loss, and an indication for CI (first CI). Exclusion criteria comprised retro-cochlear hearing loss, psychosis, below-average intelligence, visual impairment, and medical diagnoses with potential effects on cognition (such as neurodegenerative diseases). Twelve months after CI, the study population had decreased to 41 participants. The younger group (n = 20) was between 25 and 59 yr old, and the older group (n = 21) was between 60 and 75 yr old. We used audiological speech recognition tests and the Abbreviated Profile of Hearing Aid Benefit to assess hearing ability, the Beck Depression Inventory (II) to assess depressive status, and a neurocognitive test battery to evaluate cognitive status. All examinations were performed immediately before and 12 mo after the CI.

Twelve months after CI, speech recognition and subjective hearing ability had improved significantly, and depression had decreased compared with the respective status before CI. Cognitive performance improved moderately. However, the improvements were not significant. The differences in speech recognition and subjective hearing (both before and 12 mo after CI) were not associated with the differences in depression and cognitive performance (both before and 12 mo after CI). Regarding possible differences between younger and older groups, the improvement in semantic fluency was significantly more pronounced in the older group. Beyond this, we found no further significant differences between the older and younger groups.

One year after surgery in younger and older CI recipients, a reduction in depression was not associated with an improvement in cognitive performance. CI has a significant positive impact on hearing ability and reduction in depression, and age does not seem to have a crucial influence on these outcomes.