Hearing loss
The largest single midlife entry on the Lancet Commission's dementia list, and one of the few with an intervention you can buy.
goodWell supported, with the usual caveats about effect size.Revised 31 Jul 2026
The average delay between noticing hearing loss and doing something about it is measured in years.Photograph: Natanael Melchor / Unsplash
Definition
Age-related hearing loss — presbycusis — is the gradual, usually symmetrical loss of hearing sensitivity that accompanies ageing, typically affecting high frequencies first. Because consonants live in the high frequencies, the characteristic complaint is not “I can’t hear” but “I can hear you, I just can’t make out what you’re saying” — particularly in a noisy room.
Why it appears in a dementia model
In the Lancet Commission’s 2024 model, hearing loss carries the largest population attributable fraction of any single midlife factor. Three mechanisms are proposed, and they are not mutually exclusive:
- Cognitive load. Effort spent decoding degraded speech is effort not available for comprehension and memory.
- Reduced stimulation. Less auditory input over decades may accelerate atrophy in associated regions.
- Social withdrawal. Conversation becomes exhausting, so people do less of it — which puts them onto another factor on the same list.
What the evidence supports
That hearing loss is associated with faster cognitive decline is well replicated. That treating it reverses the risk is the harder claim, and the trial evidence is more mixed — with the notable finding that benefit appeared concentrated in participants at higher baseline risk rather than across the board.
That is enough to justify treating hearing loss, which is worth doing on its own terms. It is not enough to promise that a hearing aid prevents dementia, and anyone selling one on that basis is ahead of the data.
What to do
- Get tested if conversation in restaurants has become work. That is the early sign, and it precedes “I’m going deaf” by years.
- Do not wait. The typical delay between onset and first hearing aid is measured in years, and adaptation is harder the longer the auditory system has gone under-stimulated.
- Protect what you have. Noise exposure is cumulative and the damage is permanent. Power tools, concerts and headphones at volume all count.
Open questions
Whether over-the-counter hearing aids, now available in several markets, deliver the same outcomes as fitted devices is not yet settled. Whether the dementia association is fully causal remains the central uncertainty in the entry.