World Alzheimer’s Day: What the Evidence Tells Us About Vision, Hearing and Dementia

World Alzheimer’s Day is an opportunity to raise awareness of Alzheimer’s disease and the wider conversation around dementia and cognitive health as we age.

For Wellington Eye Clinic and Beacon Audiology, that conversation has particular relevance. Mr Arthur Cummings and Dr Sandra Cummings have been exploring the role vision and hearing play in healthy ageing. Research is increasingly examining these senses in relation to cognitive health too, including associations between hearing loss, untreated vision loss, social isolation and dementia risk.

That makes World Alzheimer’s Day an important moment to look more closely at what the evidence is telling us, and just as importantly, what it is not.

What do vision and hearing have to do with dementia risk?

In 2024, the Lancet Commission on dementia prevention, intervention and care identified 14 potentially modifiable risk factors associated with dementia. Hearing loss and social isolation are among them. Untreated vision loss was added in the Commission's 2024 update, alongside high LDL cholesterol. The Commission estimates that, collectively, around 45% of dementia cases could potentially be delayed or reduced by addressing these 14 factors across the course of life. That number is significant, but it can easily be misunderstood.

It does not mean that 45% of dementia cases are caused by poor vision or hearing. Vision and hearing are two factors within a much larger picture that also includes areas such as social isolation, physical inactivity, smoking, diabetes, depression and high blood pressure. A risk factor is not the same thing as a cause. And an association does not guarantee an outcome for any individual.

What are we learning about hearing?

Hearing loss has been studied extensively in relation to cognitive health.

One of the most important recent studies is the ACHIEVE trial, a randomised controlled trial investigating whether treating hearing loss could affect cognitive decline in older adults. Across the overall study population, the hearing intervention did not significantly reduce cognitive decline over three years.

However, there was an important finding among participants who were already at higher underlying risk of cognitive decline. In this group, the hearing intervention was associated with an approximately 48% reduction in the rate of cognitive decline compared with the control group. That is an important finding, but it needs careful interpretation.

It does not prove that hearing aids prevent dementia.

It suggests that addressing hearing loss may have cognitive benefits for some older adults and supports further research into the relationship between hearing and cognitive health.

What does the research say about vision?

Vision is receiving greater attention too.

A systematic review and meta-analysis of 30 studies found that visual impairment was associated with approximately a 38% higher relative risk of all-cause dementia.

Untreated vision loss was subsequently included in the 2024 Lancet Commission as a potentially modifiable dementia risk factor.

Again, the distinction matters.

The research does not establish that poor eyesight causes dementia, nor does it show that correcting vision will prevent it.

What it does is strengthen the case for considering vision, alongside hearing, when we think about cognitive health in later life.

Where does social connection fit?

This may be one of the most interesting areas when we consider vision and hearing together.

Our senses play an important role in how we communicate and participate in everyday life.

When hearing a conversation becomes difficult, or seeing well enough to participate confidently becomes harder, people may begin to engage less.

Research has found an association between hearing impairment and increased loneliness or social isolation in older adults. An eight-year study involving 5,552 older adults also found that hearing impairment was associated with 28% greater odds of social isolation.

That matters because social isolation is itself included among the Lancet Commission's potentially modifiable dementia risk factors.

One possible relationship researchers are exploring is:

Changes in hearing or vision → greater difficulty communicating and participating → reduced social engagement → potentially less social and cognitive stimulation.

But this should not be read as a simple pathway from sensory loss to dementia.

Dementia is complex and influenced by many interacting factors across a person's lifetime.

The practical message is much simpler. If difficulty seeing or hearing is making communication, relationships or everyday activities more challenging, understanding and addressing that difficulty may help someone remain engaged, participating and independent.

So what should we take from the research?

This is why the conversation around our senses needs to become broader.

Vision and hearing should not be considered important only when someone can no longer see or hear as well as they once did.

They contribute to communication, relationships, independence and participation. Research is now examining their relationship with cognitive health too.

That does not mean we should make promises the evidence cannot support.

It means we should take changes in our senses seriously.

If hearing or vision begins to change, understanding why and seeking appropriate professional assessment is preferable to simply adapting indefinitely or assuming it is an inevitable part of getting older.

Looking after hearing, vision and social connection may help people remain independent, engaged and participating in everyday life for longer.

And that is valuable regardless of dementia risk.

Why we are having this conversation together

Over recent weeks, Wellington Eye Clinic and Beacon Audiology have been sharing their perspectives on vision, hearing and healthy ageing through Lifestyle Vision & Hearing.

They are two different disciplines, requiring different expertise.

But the research gives us good reason to consider the wider picture too.

On World Alzheimer’s Day, perhaps the most useful message is not that looking after our vision or hearing can prevent dementia. The evidence does not allow us to say that. It is that healthy ageing is complex, our senses are part of that complexity, and changes in vision and hearing deserve our attention rather than our acceptance.

The more we understand about the connections between vision, hearing, social participation and cognitive health, the better equipped we are to make informed decisions about how we age.

Frequently asked questions

Does hearing loss cause dementia?

Current evidence shows an association between hearing loss and dementia risk, but this does not establish that hearing loss directly causes dementia. Dementia is influenced by many interacting factors.

Can hearing aids prevent dementia?

The evidence does not show that hearing aids prevent dementia. In the ACHIEVE trial, hearing intervention did not significantly reduce cognitive decline across the overall study population, although a benefit was observed among participants at higher underlying risk of cognitive decline.

Is vision loss associated with dementia?

Yes. A systematic review and meta-analysis found visual impairment was associated with approximately a 38% higher relative risk of all-cause dementia. Untreated vision loss is also included among the 14 potentially modifiable dementia risk factors identified by the 2024 Lancet Commission. Association does not establish causation.

Can correcting vision prevent dementia?

The research cited here does not establish that correcting vision will prevent dementia. Looking after vision remains important for sight, independence and participation, while researchers continue to investigate its relationship with cognitive health.

Why consider vision, hearing and social connection together?

Difficulty seeing or hearing can make communication and participation more challenging. Research has associated sensory impairment with social isolation, which is itself recognised as a potentially modifiable dementia risk factor. This is one possible relationship being studied, not proof of a direct pathway to dementia.

Sources

Livingston, G. et al. (2024). Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet.

Lin, F. R. et al. (2023). Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE). The Lancet.

Kuźma, E. et al. (2021). Visual Impairment, Eye Diseases, and Dementia Risk: A Systematic Review and Meta-Analysis. Journal of Alzheimer's Disease.

Shukla, A. et al. (2020). Hearing Loss, Loneliness, and Social Isolation: A Systematic Review.

Shukla, A. et al. (2024). Hearing and vision impairment and social isolation over 8 years in community-dwelling older adults. BMC Public Health.