“People can’t tell you what they can't hear,” says audiologist Douglas Beck, AuD, an expert on hearing loss and cognition who was not involved in the study. “Hearing is just perceiving or detecting sound; listening is making sense of sound. So even patients who are almost deaf—people who have moderately severe or even severe hearing loss—can often hear if you’re in a quiet room and speaking directly in front of them. They might tell you they can hear, but what they can't do is tell you what they can't hear.
“With vision, when you reach about age 45 or 50, you realize you can't read fine print anymore; everything is blurry, and so you make an appointment to get your eyes tested,” says Beck. “But in hearing, there's no real equivalent. You can't detect what you can't hear, so you’re left with comments from your spouse or friends that are easy or convenient to discount. So instead, what people start to think is, “Oh my gosh, when I was a kid, everybody had to enunciate clearly.”
Almost one-third of dementia cases in at-risk population linked to hearing loss
The estimated population attributable fraction (PAF) of 32%—or the proportion of dementia cases that might not have occurred if hearing loss were eliminated—far exceeds previous U.S. estimates, which have typically ranged from 2% to 19%.
The authors say several factors likely account for this difference. Earlier studies often relied on self-report data, which underestimated prevalence. Others used formulas for calculating PAFs that can be biased downward when numerous risk factors are present. Additionally, studies that used audiometric data typically found only a weak association between mild hearing loss and dementia.
This new estimate also surpasses the 8% figure reported by the influential 2020 Lancet Commission on Dementia Prevention, which adjusted for overlapping risk factors such as hypertension and diabetes.2 The authors of the present study contend that such adjustments may underestimate the true contribution of hearing loss, especially when risk factors work together through similar biological or behavioral pathways, such as sensory deprivation, social isolation, or increased cognitive load.
PAF estimates were generally higher among women, White participants, and those over age 75, largely reflecting differences in hearing loss prevalence across these groups. However, the authors caution that small sample sizes, especially among Black participants, limited the precision of their estimates.
In comments to HearingTracker, study co-author Jason Smith, PhD, a researcher in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health, underscored the population-level aspect of the research. “We acknowledge that we still don’t know with certainty whether treating hearing loss reduces an individual’s risk of dementia,” he said. “However, this provides strong evidence, within the same sample that demonstrated benefit in ACHIEVE, that a large fraction of population-level dementia risk could be associated with hearing loss. The fact that up to 32% of population-level dementia risk could potentially be delayed or prevented from treating hearing loss in older adults signals a major prevention gap.
“The public health implications that addressing an important modifiable risk factor—even in later life—could delay a large fraction of dementia risk at the population level are encouraging,” added Smith. “Yet more research is needed to investigate whether treating hearing loss at the individual level can reduce dementia risk.”