Analysis: The link between sensory loss and dementia is an emerging area of science and one with great potential for dementia prevention
In Ireland, about 64,000 people are currently living with dementia, but this number is projected to more than double in the next 20 years. This has far-reaching consequences, for both individuals and our healthcare systems. While no cure for dementia exists, research shows that lifestyle factors can help delay, or in some cases even prevent, its onset.
Dementia is a term used to describe a group of conditions that cause a gradual decline in thinking abilities. This decline typically unfolds in stages. Research shows that brain changes connected to dementia could start up to 20 years before symptoms like memory loss become noticeable. During this so-called "preclinical stage", a person may seem and feel healthy while subtle brain changes are unfolding.
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From RTÉ Radio 1's Today with Claire Byrne, the link between hearing loss and the risk of dementia
While the thought of unnoticed changes unfolding in the brain may sound unsettling, it also creates a valuable time window in which progression to dementia may still be slowed or even prevented. In fact, researchers have identified a list of 14 risk factors that, when addressed, may prevent or delay up to 45% of dementia cases worldwide, such as smoking or physical activity.
Hearing and vision loss as risk factors for dementia
Two important factors that the report lists as needing attention to prevent dementia are hearing and vision loss. While changes in vision and hearing are often considered a normal part of ageing, they may also reflect changes in brain health. More specifically, recent research has highlighted that the risk for dementia is increased in individuals with hearing or vision loss compared to those with normal sensory function.
Additionally, when both senses are affected, the risk appears even higher. In a recent analysis combining results from multiple studies on the topic, our team found that individuals experiencing both hearing and vision impairment have a 53% higher risk of developing dementia than those without sensory loss. Strikingly, we found that this risk is likely greater than the sum of its parts. In other words, when both senses are impaired, the risk is even higher than one would expect if they simply added the two risks together.
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From RTÉ Radio 1's Brendan O'Connor Show, Prof Emer McGrath on a dementia risk study which identifies 11 key factors behind the condition
How are the senses and dementia linked?
The exact link between the senses and dementia is not fully understood, but scientists have several theories. One possibility is that sensory loss reflects early changes in the brain. The same biological processes that cause dementia, such as the build-up of abnormal proteins or reduced blood flow, could also affect the visual and auditory systems.
Another explanation is that decreased sensory input directly contributes to a decline in brain health. When our eyes or ears send lower-quality information to the brain, it receives less stimulation, leading to structural and functional changes over time - much like how muscles weaken when not used. These brain changes could be linked to dementia.
It is also possible that the brain and senses are connected by a third factor, such as social isolation. People with hearing or vision loss may withdraw from conversations or social activities. Over time, reduced social interaction can increase loneliness, which is linked to a higher risk of dementia.
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From RTÉ Radio 1's Drivetime, Dr Fiona Skelly from TUS Athlone on a new project which shows how céilís can help dementia patients improve cognitive functions like attention and concentration
While it is unclear yet which theory best explains the link between sensory impairment and dementia, in reality, they may all play a role, combining biological, psychological, and social factors into a complex relationship between the senses and the mind.
The good news: sensory health can be modified
While a link between dementia and sensory loss might sound alarming, it also offers hope. Unlike some risk factors for dementia, such as age, hearing and vision problems are often treatable. Studies suggest that addressing sensory impairments through hearing or vision aids may eliminate the additional risk of dementia linked to sensory impairment. In other words, wearing glasses and hearing aids might be the solution to decreasing the dementia risk associated with sensory loss.
Taking care of your hearing and vision could also mean taking care of your brain
But despite this, routine sensory checks are not always part of midlife healthcare in Ireland. Making regular hearing and vision tests a standard part of health screening could be a simple but powerful way to support brain health. Additionally, public education on the importance of sensory health and how it connects to dementia could encourage earlier action and reduce stigma around sensory aids.
The link between sensory loss and dementia is an emerging area of science, and one with great potential for dementia prevention. As the world's population ages, even modest reductions in dementia risk could have a major public health impact.
So, if you notice that conversations seem harder to follow or your glasses aren’t doing the job anymore, don’t dismiss it. Taking care of your hearing and vision could also mean taking care of your brain.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
