Among other changes that occur with age, you can expect your hearing and vision to change. Age-related hearing loss, for example, affects around 50% of people over the age of 75. Diseases that cause vision loss are also common with age.
Decreased hearing and sight can have a dramatic effect on your daily life: you may have difficulty participating in conversations, driving, recognizing distant friends and finding many other daily activities out of reach. .
There is also a general concern: in addition to a known link between hearing loss and dementia, recent studies show that when people have both visual and hearing impairment, what is called dual sensory impairment (DSI), their risk of dementia increases dramatically.
“There have been a number of research studies,” says Harvey Abrams, PhD, a longtime audiology research expert who now works for hearing aid company Lively. “Across the board, I think the results are pretty compelling that dual sensory impairment is at higher risk than either impairment. [alone],” he says.
A remarkable recent discovery: A person with DSI has an eight times higher risk of dementia, according to a May 2022 study in the Journal of Alzheimer’s Disease Reports.
If you or a loved one has both untreated vision and hearing impairment, what should you think of these results? Read on for what’s currently known and what’s yet to be discovered.
Why could dementia and sensory impairments be linked?
Researchers know there is a link between sensory impairments and dementia, but the cause of this link remains unknown. That said, there are credible theories as to the “why” behind the link, the most common being:
- Common cause theory: There could be an underlying problem, such as a vascular disorder affecting blood flow to your brain and ears, which leads to sensory and cognitive impairment. The theory here: The same underlying problem leads to two impairments, says Abrams.
- Cognitive load theory“As you get older, you suffer from some cognitive decline,” says Abrahms. This means you have fewer resources available when you need to hear in a noisy environment or process a lot of visual information, he says. With the theory, the assumption is that if you have hearing loss, then your brain goes the extra mile to help you listen, draining your overall cognitive resources.
- Waterfall theory: Loss of hearing or sight can cause people to withdraw from relationships and reduce physical activity. It makes sense: why go to the theater with a friend if you can’t hear the actors, see the scenery, or talk to your friend easily? This can have considerable effects. “Hearing or visual impairment may lead to behaviors and lifestyle that indicate a higher risk for dementia,” according to a comment in JAMA Open Network.
- The “precursor” hypothesis: This is also sometimes called overdiagnosis. The idea behind this theory is that if you can’t fully hear or see instructions, you may not do well on tests that assess your cognitive abilities.
“It makes sense that problems with both senses create greater risks,” says Abrams. With cognitive load theory, for example, it’s clear that two diminished senses add an extra load to your brain’s resources. Or alternatively, it could make following instructions and answering questions on a cognitive test much more difficult.
What the Research Says About DSI and Dementia
As Abrams points out, many studies have looked at DSI and cognitive decline.
They don’t all use the same methodology and don’t always have the same results, he notes. They may, for example, define hearing or visual impairment differently, or examine different populations. Generally, however, “impairment” meant that a person had difficulty seeing or hearing, even if they wore glasses and/or hearing aids.
Here is an overview of some notable recent discoveries:
The May 2022 study published in JAMA Network Open found that “dual sensory impairment was associated with a 160% increased risk of all-cause dementia and a 267% increased risk of Alzheimer’s disease.”
There were nearly 3,000 participants in this cohort study, and they reported whether they had hearing impairment or visual impairment. (If people wore hearing aids or glasses but still couldn’t do everyday activities, like talk on the phone or drive, they were asked to say they had a disability.)
Of note: Although dual sensory impairment is associated with dementia risk, there was also a significant association with a single sensory impairment, according to the study.
The Journal of Alzheimer’s Disease Reports reviewed data from the American Community Survey, which includes more than 5 million adults aged 65 or older. This analysis found that for these older adults, sensory impairments increased their risk of cognitive impairment – hearing impairment carried more than double the risk, while visual impairment carried more than three times the likelihood of cognitive impairment. Most dramatic of all: older people with DSI had an eight times higher risk of cognitive impairment.
In this study, as in the one above, impairment was self-reported. For cognitive impairment, people had to answer yes or no to this question: Due to a physical, mental or emotional condition, does this person have serious difficulty concentrating, remembering or taking decisions ?
Similarly, a June 2022 cohort study in Frontiers in Aging Neuroscience, which looked at over half a million people in the UK, also found that participants with visual impairment had a 50% higher risk. of developing dementia, while people with hearing loss had a 42% higher risk. The risk of developing dementia in people with dual sensory impairment was still the highest: 82%.
A note on what the studies reveal and their limitations
“Statisticians are my heroes,” says Abrams.
This is because they are able to filter out factors that could potentially increase dementia risk (think: upbringing, BMI, upbringing, age, etc.) from the data. This allows researchers to shed light on the impact of sensory impairments, without other potential dementia risk factors influencing the results.
However, the studies have limitations. In fact, if you read articles, there will almost always be a section detailing them. For example, could self-reporting of impairments underestimate their severity? Are there other factors that are not taken into account?
Additionally, it’s important to note that the researchers found a statistically certain link, but not a causal link, notes Abrams. That is, dual sensory impairment and dementia are related, but it is not clear that these impairments cause dementia.
It’s not yet known if sensory impairment causes dementia, just that there’s a link
It is also unclear to what extent glasses and hearing aids reduce the risk.
“Future research is also needed to examine how standard treatments for hearing and visual impairment, such as hearing aids, may influence cognition,” noted the authors of the Alzheimer’s disease reports.
Finally, Abrams notes that everyone, with or without sensory impairment, is at risk for dementia. What is revealed by recent studies is that your relative risk is higher if you have one sensory impairment, and even higher if you have two sensory impairments, he explains. Dementia can occur whether you have DSI, or not. “It’s just that you have a higher risk” compared to someone without sensory impairment, Abrams says.
Think of it this way, Abrams says: Wearing a seat belt reduces your risk of injury or worse in a car crash, but doesn’t eliminate it. And, some people who stubbornly refuse never suffer damage in a car accident. Their risk is higher, but it’s not set in stone.
What can you do if you have hearing and visual impairments?
First, it’s always better to know, says Abrams.
It helps to be aware that there is “a risk associated with hearing loss, visual impairment, and that risk is greater with both and either alone,” he says.
This is true for patients and doctors too.
For an audiologist, everything is an ear, while for an optometrist, everything is an eye, Abrams points out. But these studies show that the two specialists would benefit from making referrals and explaining the increased risk of two sensory impairments to patients. And, practitioners testing dementia and cognition might want to confirm that sensory limitations do not skew patient results.
Awareness of the link between sensory impairments and dementia can motivate you to be vigilant about getting your hearing and vision checked, and to take advantage of treatment options. After all, research indicates that treating hearing loss, for example, can decrease cognitive decline.
The importance of treatment
If you or a loved one notice changes in your vision and hearing, make an appointment with a healthcare professional. If you are diagnosed with dual sensory impairment, work closely with your medical team to identify appropriate assistive devices, coping strategies, and other rehabilitation activities. to meet your individual needs. Most importantly, enlist the help of your loved ones in the process of education and rehabilitation.
Combined with other health issues associated with aging, double sensory loss can seem overwhelming, said Dr. Ying-Zi Xiong, PhD, postdoctoral researcher at the Gigi & Carl Allen Envision Research Institute in Wichita, Kan. (ERI) and research associate at the University of Minnesota.
The good news: Studies show that people who receive treatment for dual sensory impairment have a better quality of life and lower risk of death than people who don’t receive treatment. You’re never too old for hearing aids.
“Family support is crucial for older people who face double sensory loss,” Xiong said. “We need to be patient when seniors have communication issues and encourage them and create opportunities for them to engage in social interactions.”