A new prospective cohort study revealed that nearly one-third of incident dementia cases in older adults could be attributed to clinically significant hearing loss, highlighting the potential importance of hearing interventions for dementia prevention.

Key Findings

In the study, published in JAMA Otolaryngology–Head & Neck Surgery, investigators from the Johns Hopkins Bloomberg School of Public Health and other institutions analyzed data from 2,946 participants aged 66 to 90 years who participated in the ARIC-NCS study with up to 8 years of follow-up (2011 to 2019). They found that the population attributable fraction (PAF) of incident dementia from any audiometric hearing loss was 32.0%.

"This cohort study suggests that treating hearing loss might delay dementia for a large number of older adults," the study authors indicated. "Public health interventions targeting clinically significant audiometric hearing loss might have broad benefits for dementia prevention," they added.

Methodology

The investigators included community-dwelling older adults without dementia at baseline who underwent hearing assessment. They measured hearing loss both objectively (audiometry) and subjectively (self-reported) and followed the participants for development of incident dementia, which was diagnosed through a standardized algorithmic process with expert panel review.

Among the participants, 66.1% of them had audiometric hearing loss, whereas just 37.2% of them self-reported hearing loss. During the median follow-up of 6.6 years, 8% (n = 239) of the participants developed incident dementia.

Subjective vs. Objective Measures

Notably, self-reported hearing loss wasn't associated with an increased risk for dementia (hazard ratio < 1), making the PAF unquantifiable. This finding underscored the importance of using objective measures when assessing hearing-associated dementia risk.

"Future research quantifying [PAF] should carefully consider which measures are used to define hearing loss, as self-reporting may underestimate hearing-associated dementia risk," the study authors stated.

Demographic Variations

The investigators revealed that PAFs from audiometric hearing loss were larger among:

• Adults 75 years and older compared with those younger than 75 years (22.0%)

• Female participants compared with males (24.0%)

• White participants compared with Black participants (22.9%).

Clinical Implications

The findings aligned with recent evidence from the randomized ACHIEVE clinical trial, which demonstrated that treating hearing loss reduced the rate of 3-year cognitive decline by 48% among ARIC participants compared with controls.

The study authors noted: "Relative to other potentially modifiable risk factors earlier in life (PAFs: midlife obesity = 18%; physical inactivity = 12%; low education = 12%), the preventive potential from addressing [hearing loss] in late life in the [United States] could be sizeable," they continued.

Limitations

The study had several limitations, including potential limited generalizability beyond the community-based cohort of self-identified Black and White adults and possible survivor bias. Additionally, while the study captured hearing aid use, it lacked information on appropriate hearing aid use, fit, and compliance.

As global dementia cases are expected to triple in the coming decades, these findings suggested that addressing hearing loss could be a crucial component of population-level dementia prevention strategies.

Disclosures are available in the study.