Restorative hearing aids may help stave off cognitive decline in those with hearing loss

Restorative hearing devices may help stave off the risk of cognitive decline in patients with hearing loss, according to a systematic review and meta-analysis of 31 studies.

The use of restorative hearing devices was significantly associated with a 19-percent reduction in the risk for long-term cognitive decline in those with hearing loss compared with counterparts who had uncorrected hearing loss. Importantly, this benefit was evident for both normal baseline cognition and baseline mild cognitive impairment. [JAMA Neurol 2022;doi:10.1001/jamaneurol.2022.4427]

Until this study, no meta-analysis has pooled the available evidence on the cognitive benefit of restorative hearing devices. “To the best of our knowledge, this is the first comprehensive quantitative synthesis looking at associations between hearing restoration and cognitive decline,” said the researchers led by Dr Brian Sheng Yep Yeo from the Yong Loo Lin School of Medicine, National University of Singapore.

Yeo and colleagues analysed both cognitive scores and longitudinal data to determine if there was any association between restorative hearing devices (cochlear implants and behind-the-ear or in-the-ear hearing aids) and cognitive impairment and incident dementia.

Of 3,243 studies screened, 31 were included, 19 of which made up to the quantitative analyses. Eight studies with a follow-up duration of 2–25 years showed significantly lower risks of any cognitive decline among hearing aid users vs those with uncorrected hearing loss (HR, 0.81; 95 percent confidence interval [CI], 0.76-0.87; I² = 0 percent).

Other than the cognitive benefits, the use of hearing devices was associated with a 3-percent improvement in cognitive test scores assessing general cognition in the short term.

“These findings were robust to subgroup analyses, quantitative assessments of publication bias, as well as cumulative and leave-1-out meta-analyses,” said the researchers.

Hearing loss a risk factor for dementia

Hearing loss has been identified as one of the top modifiable risk factors for dementia, accounting for a 9-percent risk reduction. [Lancet 2017;390:2673-2734] Studies suggest hearing aids may attenuate dementia onset [Alzheimers Dement (N Y). 2021;7(1):e12122], possibly by reducing cognitive load or correcting sensory deprivation in individuals with hearing loss.

“The current study further adds value by suggesting that correcting for this sensory deficit is associated with a slower decline in cognition,” said the researchers, adding that the cognitive benefit of restorative hearing devices should be further investigated.

Consider hearing evaluation

There were several takeaways from the study, commented Dr Michael Denham from the New York Presbyterian/Columbia University and colleagues, in a separate editorial. [JAMA Neurol 2022;doi:10.1001/jamaneurol.2022.4155]

“This meta-analysis provides convincing evidence that hearing aid usage is associated with a considerable risk reduction of cognitive decline. While this finding does not prove a causal relationship, it provides convincing evidence that physicians should consider hearing evaluation … as part of a standard workup for patients who may be experiencing cognitive decline.”

Future studies should examine patients with no baseline cognitive impairment and those with mild cognitive impairment as each group may provide unique risk profiles and trajectories for cognitive decline, the researchers proposed.

Lastly, the study is “a testament to the power of pooling studies in meta-analysis,” they added.