The cheapest piece of equipment that has been shown to substantially reduce a person’s lifetime risk of developing dementia is not a medication, a meditation practice, or an exercise routine. It is a small plastic device, typically beige or transparent, that fits behind the ear and amplifies sound. According to a study published in JAMA Neurology on 18 August 2025, adults with hearing loss who began using hearing aids before the age of 70 went on to develop dementia at approximately 61 percent the rate of comparable adults with untreated hearing loss. The effect held up across more than two decades of follow-up. It survived statistical adjustment for age, sex, vascular risk factors, and educational background. It is one of the largest single-intervention effects on dementia risk that has been documented in any peer-reviewed study to date — and it sits, in 2026, almost entirely unused by the population it would most benefit.
The study, led by Lily Francis of the University of Texas Health Science Center at San Antonio with senior author Sudha Seshadri, drew on data from the Framingham Heart Study — the longest-running cardiovascular and public-health cohort in American medical research, originally launched in 1948 in the Massachusetts town of Framingham. According to Hearing Tracker’s coverage of the study, citing the Francis et al. paper directly, the research team analysed records from 2,953 participants in the Framingham original and offspring cohorts who were aged 60 or older at baseline and free of dementia at the start of observation. The participants had received pure-tone audiometric hearing assessments between 1977-1979 (original cohort) and 1995-1998 (offspring cohort), and had been tracked for up to 20 years afterward for incident dementia. By the end of follow-up, 583 of the participants — approximately 20 percent — had developed dementia.
What the data showed
The headline finding was specific to a particular age group. According to Medscape’s detailed report on the statistical findings, participants who were younger than 70 at the time of their hearing assessment and who had hearing loss showed a sharp split based on whether they used hearing aids. Those with untreated hearing loss developed dementia at the highest rate. Those who used hearing aids had a 61 percent lower risk of dementia (hazard ratio 0.39, 95% confidence interval 0.17 to 0.89, P=0.03). Participants under 70 with no hearing loss at all sat in between, with a 29 percent lower risk than the untreated-hearing-loss group. The under-70 finding was robust across multiple statistical models including adjustments for cardiovascular risk and education.
For participants 70 or older at the time of their hearing assessment, the protective association disappeared. Hearing aid use in this older subgroup was not significantly associated with reduced dementia risk in any of the models the team examined. Seshadri, the senior author, offered a clinical interpretation of the age dependence: “The impact of correcting risk factors is, for most risk factors, greatest in midlife between ages 50-75.” Older adults whose hearing has been untreated for many years may have already accumulated brain changes — atrophy, reduced cognitive reserve, persistent social disengagement — that hearing aids alone cannot reverse. The implication is that hearing aids work as a dementia-prevention tool, but their effect appears to depend substantially on timing.
Why hearing might matter for the brain
The mechanistic explanations for why treated hearing loss reduces dementia risk are not yet fully established, but the broader literature converges on several plausible pathways. The first is cognitive load. When the auditory system delivers degraded signals to the brain, the brain has to expend more processing resources to extract meaning — leaving less cognitive capacity available for memory formation, attention, and other higher-order functions. Over years and decades, this chronic cognitive overhead may contribute to faster cognitive aging. Hearing aids reduce the load by restoring clearer auditory input, freeing up cognitive resources.
The second pathway is social. Hearing loss makes conversation effortful and often embarrassing, and many people with untreated hearing loss progressively withdraw from social activities — phone calls, group meals, religious services, family gatherings, professional meetings — to avoid the difficulty. The resulting social isolation is itself an established dementia risk factor, identified by the 2024 Lancet Commission on Dementia Prevention as one of 14 modifiable risk factors. Hearing aids that restore conversational ability tend to restore social engagement as well. The third pathway is structural: untreated hearing loss has been associated in imaging studies with faster atrophy of brain regions involved in auditory and language processing, and the structural changes may have downstream effects on broader cognitive function.
What stands in the way
Given the size of the documented effect and the modest cost of the intervention, the central public-health puzzle is why so few of the people who could benefit from hearing aids actually use them. According to the National Institute on Deafness and Other Communication Disorders’ official statistics on hearing health, approximately 28.8 million US adults could benefit from using hearing aids, but among adults aged 70 and older with hearing loss who could benefit, fewer than 30 percent have ever used them. Among younger adults with hearing loss — exactly the group the 2025 Framingham analysis identifies as gaining the most from hearing aids — the adoption rate is substantially lower still. Across the entire population of Americans with hearing loss of any severity, between 60 and 90 percent never use hearing aids at all.
The reasons for this gap are well-documented in the public-health literature. According to a 2025 PMC review of insurance status and hearing aid utilization in older US adults, the leading barrier is cost. Prescription hearing aids in the United States typically cost between $2,000 and $5,000 per pair. Original Medicare does not cover hearing aids or fitting examinations at all. Some Medicare Advantage plans offer partial hearing benefits, but coverage varies enormously by plan. Medicaid hearing aid coverage varies state by state and is often limited. The 2022 FDA regulation permitting over-the-counter hearing aids for mild-to-moderate hearing loss has reduced costs substantially for some users — OTC aids run $200 to $1,500 per pair — but uptake of OTC devices has been slower than initially projected. Other barriers include the perceived stigma of using a visible aging-related device, the gradualness of hearing loss (which often goes unrecognised for years), and the typical delay of 7 to 10 years between when a person first becomes aware of hearing difficulty and when they finally pursue treatment.
What the study does not prove
The Francis et al. 2025 paper is an observational study rather than a randomised trial, and the authors acknowledged several limitations. Hearing aid use was self-reported and measured as a binary variable, with no information on how consistently or how many hours per day each participant actually wore their device. The study could not distinguish whether the protective effect was driven specifically by the age of intervention or by the underlying severity of hearing loss. People who chose to buy and wear hearing aids may have differed from non-users in unmeasured ways — better access to healthcare, higher health literacy, more proactive engagement with their own well-being — that could partly explain the dementia difference.
The 2025 finding does not, on its own, prove that hearing aids cause reduced dementia risk. What it adds to the existing literature, including the 2023 ACHIEVE randomised controlled trial which showed slowed cognitive decline in high-risk adults using hearing aids, is the specific temporal claim that the protective effect is concentrated in adults who begin treatment before age 70. The combined weight of the available evidence is now substantial enough that the 2024 Lancet Commission on Dementia Prevention identified hearing loss as the single most prevalent modifiable risk factor for dementia globally, accounting for approximately 8 percent of all dementia cases. The most effective response to this risk factor — early-life hearing aid use — is one of the cheapest, lowest-risk, and most widely available interventions in the modern medical toolkit. The reason it remains so widely unused is not that the evidence is unclear. The evidence is increasingly clear. The reason is that the device itself sits at the intersection of cost, insurance coverage, social stigma, and the slow human pace at which gradual hearing loss becomes a noticed problem. The Framingham 2025 finding makes the case for closing that gap as urgently as any single piece of public-health data published in the past decade.
