Hearing Loss Tied to Cognitive Decline

Mild or disabling hearing loss in middle-aged and older adults is associated with cognitive impairment, new findings show. However, unlike in previous studies, investigators found no cognitive benefit from wearing hearings aids, except in people with depression. 

“Altogether, the present findings combined with prior evidence support that patients with hearing loss are at higher risk of cognitive impairment,” lead author Baptiste Grenier, MD, Université Paris Cité, Paris, France, and colleagues wrote.

Investigators say that their findings suggest “it may be useful to monitor cognitive function in middle-aged individuals with hearing loss.”

The findings were published online on October 1 in JAMA Network Open. 

Modifiable Risk Factor

About half of all adults aged 60-65 years are affected by hearing loss, which was identified as one of a dozen modifiable risk factors for dementia in a 2020 Lancet Commission report, the authors noted.

Although prior research has shown a link between hearing loss and cognitive decline, Grenier and colleagues noted that earlier studies often included small sample sizes, relied on self-reports, or used only a single cognitive test.

For this study, investigators analyzed data on more than 62,000 older people aged 45-69 years (mean age, 57 years) who were part of the population-based CONSTANCES cohort.

Tests administered at baseline determined hearing status as normal (pure tone average [PTA]

All participants aged 45 and older also underwent an extensive cognitive evaluation. The researchers computed a global cognitive score for the participants based on three of the tests: Digit Symbol Substitution Test of attention, psychomotor speed, and reasoning; Free and Cued Selective Reminding Test of episodic verbal memory; and Trail Making Test of shifting abilities and executive function. 

In addition, investigators measured variables such as depression and social deprivation, a socioeconomic measure. 

A Link With Cognitive Decline

Overall, 49% of participants had normal hearing, 38% had mild hearing loss, 10% had disabling hearing loss without use of a hearing aid, and 3% used a hearing aid.

Across all ages, 27% of individuals with mild hearing loss and 37% with disabling hearing loss had global cognitive scores indicative of impairment, compared with 16% of those with normal hearing (P

Global cognitive impairment risk did not differ between participants with disabling hearing loss who used a hearing aid and those who did not, except among those with depression (P = .02). 

The study authors speculated that a few mechanisms could be driving the association, including social isolation stemming from hearing and cognitive impairments and cognitive decline resulting from prolonged auditory input deprivation.

Shared neurodegenerative processes associated with both hearing loss and cognitive impairment may also play a role, they added.

Hearing Aid Benefit: Yes or No?

The findings are the latest in a series of studies linking hearing loss to cognitive decline; the largest of these is the randomized, controlled ACHIEVE trial of nearly 1000 participants. 

As reported by Medscape Medical News, the ACHIEVE trial showed that in a subgroup of 238 participants who were at higher risk for cognitive decline and dementia, hearing aid use was associated with a 48% reduction in risk for cognitive decline. 

However, in this new study, researchers found no difference in risk for cognitive impairment between those with hearing loss who wore hearing aids and those who did not, except among those with depression. 

“Hearing aid prescription in patients with disabling hearing loss should be guided by their established benefits on quality of life and social isolation, but not to mitigate cognitive decline for which further research is needed,” they wrote.

Comparing the present study with the ACHIEVE trial is similar to comparing “apples to kumquats,” David Knopman, MD, professor of neurology at the Mayo Clinic in Rochester, Minnesota, and a co-investigator on the ACHIEVE trial, told Medscape Medical News. 

“This was an observational study, where there are inherent biases built into the study, and so the data will not necessarily align with ACHIEVE, a randomized, controlled trial,” he said, adding that the average age of participants in the ACHIEVE trial was 75 years, as opposed to 57 in the French study.

Knopman pointed out that the cognitive decline in participants of the current study was probably could not be attributed to dementia, owing to the age range of the participants, whereas it was in the ACHIEVE trial. 

Alison Huang, PhD, MPH, a senior research associate at Johns Hopkins University in Baltimore who also worked on the ACHIEVE trial as a co-investigator, told Medscape Medical News that hearing aid use may have reduced cognitive decline in participants with depression because “depression is a potential mediating factor between hearing loss and cognitive decline — it could be that people with hearing loss have difficulty communicating with others, doing the things they enjoy, which can lead to depression, and depression is just one risk factor for depression.”

She also noted that the cross-sectional design of the study — which study authors acknowledged as one of its major limitations — made it impossible to know this for certain, however. 

In addition to the cross-sectional design, which limits interpretation of the associations between hearing loss, hearing aid use, and cognitive impairment, other study limitations include that a lack of data on the duration of hearing aid use and whether that use preceded onset of cognitive impairment. 

The study was funded by the Caisse Nationale d’Assurance Maladie, the Ministry of Health, the Council of the Ile de France Region, and the Cohorts TGIR IReSP-ISP INSERM. No conflicts of interest were reported.