I have recently found myself thinking about this more than I used to. I have noticed how many of my older patients are living with untreated hearing loss, and have discovered the links between this and cognitive impairment… Untreated hearing loss includes patients who don’t want to get their hearing tested AND those who have hearing aids but don’t want to wear them. Hearing loss is a risk factor for dementia that receives little attention compared with others like high blood pressure and smoking. A 2024 report from the Lancet Commission changed how I think about this: it identified hearing loss as the single largest modifiable risk factor for dementia in midlife - larger than any other factor we know of.
The association itself is well-established. A meta-analysis of six large longitudinal studies, each following at least 500 participants for a minimum of five years, estimated a 37% increased risk of developing dementia attributable to hearing loss. What is less settled is the mechanism, because the answer has implications for whether treating hearing loss can actually protect the brain.
There are three main hypotheses, and they are not mutually exclusive. The first is cognitive load: when hearing is impaired, the brain has to work harder to decode degraded sound, diverting resources away from other cognitive functions like memory and executive processing. Over years, this chronic overload may accelerate decline. The second is social isolation: poor hearing leads to withdrawal from conversation and social engagement, and social isolation is itself an independent risk factor for dementia. The third suggests that the same underlying processes driving neurodegeneration also damage the pathways for hearing, meaning that hearing loss may sometimes be an early symptom of dementia rather than a cause.
Most researchers now think all three mechanisms are probably operating simultaneously, which is what makes this relationship so hard to disentangle. The most important clinical question is whether treating hearing loss can slow cognitive decline. The ACHIEVE trial.. currently the largest randomised controlled trial to address this.. gave a nuanced answer. In the overall study population of 977 adults with mild to moderate hearing loss, the hearing intervention did not significantly slow three-year cognitive decline. However, in a prespecified subgroup of participants with multiple cardiovascular and metabolic risk factors for cognitive decline, hearing aids slowed decline by 48%. A secondary analysis found that in participants in the top quartile of predicted cognitive risk, the benefit was 62%.
The honest interpretation is that hearing aids are not a universal cure for dementia risk, but they appear to matter most for the people who are already at highest risk of cognitive decline. Given that most people with hearing loss go untreated for years, and given the evidence that early treatment may offer the greatest benefit, the case for getting a hearing assessment and addressing hearing loss promptly is strong, and this is not just about quality of life.
👋 For the new joiners: I’m Suraj, also known as Dr Sooj - a primary care doctor & health content creator. I love navigating the complex world of health and wellness and breaking down complicated concepts.
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References:
1. Livingston G, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. Lancet. 2024;404(10452):572–628.
2. Warren JD, et al. Hearing impairment and dementia: cause, catalyst or consequence? Cortex. 2025; PMC12084262.
3. Lin FR, et al. Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE): a multicentre, randomised controlled trial. Lancet. 2023;402(10404):786–797.
4. Deal JA, et al. Cognitive benefits of hearing intervention vary by risk of cognitive decline: A secondary analysis of the ACHIEVE trial. Alzheimers Dement. 2025; PMC12078761.