'Convincing Evidence' Hearing Aids Reduce Dementia Risk

Kelli Whitlock Burton

December 05, 2022

Hearing aids significantly reduce the risk for cognitive decline and dementia and even improve short-term cognitive function in individuals with hearing loss, a new study suggests.

The use of hearing restorative devices was associated with a 19% reduction in cognitive decline. The data suggest that the protective benefits accrue over time and that even those with some dementia when they begin wearing hearing aids see improvement.

The large meta-analysis pools data from smaller studies and provides what outside experts call "convincing evidence" that using hearing restorative devices could help prevent dementia.

"Encouragingly, even patients who already started with mild cognitive impairment, or early dementia, in our pooled analysis also benefited from the use of hearing aids, as they also had approximately 20% lower risk of progressing to dementia," Benjamin Tan, MBBS (Hons), Dean's Fellow at the Yong Loo Lin School of Medicine, National University of Singapore, told Medscape Medical News. "This means that it is never too late to start using hearing aids, but early treatment may help to preserve the most cognition."

The findings were published online today in JAMA Neurology.

Known Risk Factor

Hearing loss is a known risk factor for dementia. However, the few studies that have explored the protective benefits of hearing aids have been small and yielded conflicting results.

The systematic review and meta-analysis included 31 studies with 137,484 participants whose average age ranged from 64-86 years. The studies followed participants for 2-25 years.

A pooled analysis of 126,903 participants revealed that hearing aid users had a significantly lower risk of any cognitive decline compared with those with uncorrected hearing loss (hazard ratio [HR], 0.81; 95% CI, 0.76 - 0.87), even after adjusting for age, gender, education, socioeconomic status, and comorbidities.

Hearing aid usage was associated with significantly lower odds of cognitive impairment (HR, 0.79; 95% CI, 0.65 - 0.97), conversion from mild cognitive impairment to dementia (HR, 0.73; 95% CI, 0.60 - 0.88), and incident dementia (HR, 0.83; 95% CI, 0.77 - 0.90) compared with those who didn't wear hearing aids.

The results were similar in studies conducted in North America, Asia, and Europe.

"Our study, through pooled data, shows that the active management of hearing loss can potentially help to reduce or delay cognitive decline," study investigator Woei Shyang Loh, associate professor and head of Otolaryngology at the National University Hospital and National University of Singapore, told Medscape Medical News.

Earlier Usage, Greater Benefit

To be beneficial, hearing aids should be worn for more than 4 hours a day, Loh said. People with advanced dementia may struggle to use the devices for that long.

"As such, we think that the earlier the use of hearing restorative devices, the better might be the outcome," Loh said.

The benefits of hearing loss intervention may not be limited to reduced risk for cognitive include, the researchers found. A pooled analysis of 568 participants revealed a 3% improvement in cognitive test scores after the use of hearing restorative devices (pooled ratio of means [ROM], 1.03; 95% CI, 1.02 - 1.04).

Whereas that improvement was only statistically significant in people who used cochlear implants, Tan noted that there were nearly twice as many studies of cochlear implants compared with hearing aids, so the sample size may have been too small to detect a significant effect for hearing aids.

"It is quite possible, and I would argue even likely, that when more studies are published and we re-run the analysis, the effect may also become statistically significant for hearing aid users," Tan said. "I don't think these results support the superiority of cochlear implants."

Prevention the Best Defense

In an accompanying commentary, Justin S. Golub, MD, associate professor in the Department of Otolaryngology-Head and Neck Surgery at Columbia University Vagelos College of Physicians and Surgeons, New York City, and co-authors note the study offers "convincing evidence that hearing aid usage is associated with a considerable risk reduction of cognitive decline."

Although the research demonstrates a strong association between hearing aid use and preservation of cognitive function, the study does not demonstrate causation, Golub told Medscape Medical News.

"It is very important to establish causation, but it is also very difficult to do that. Causation is the way we can know for sure that if you treat A — hearing loss — then you will reduce B — cognitive decline or dementia. This is what we care about," Golub added.

Establishing causation is difficult and usually requires randomized controlled trials. One such trial, ACHIEVE, is currently underway and should offer results soon.

Meanwhile, this new work offers the most comprehensive findings to date, Golub said.

"Given that hearing loss may be causally related, is common, and is rarely treated, it represents one of the most powerful potential modifiable risk factors for cognition/dementia," Golub said.

"Dementia is one of the greatest public health threats," he added. "It has no good treatment. Clinical trial results of new anti-amyloid drugs have been modest at best. Prevention is our best offense."

Study funding was not disclosed. The study authors report no relevant financial relationships. Golub reported consulting expenses from Alcon. The other editorialists report no relevant financial relationships.

JAMA Neuro. Published online December 5, 2022. Full text, Editorial

Kelli Whitlock Burton is a reporter for Medscape Medical News covering neurology and psychiatry.

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