Whether it’s called a puzzle, a maze, a computer or one of the greatest mysteries in the world: the human brain and its capacity for emotion, critical thinking, wonder and communication are complicated to say the least. . When illness reduces the mind’s ability to do these things, the consequences can be devastating.
It’s no wonder, then, that we spend a lot of time unraveling the links and trying to uncover different risk factors for dementia, an umbrella term for symptoms that impact thinking, memory, language and communication. . One factor that has come to light recently is vision.
A July study published in JAMA Ophthalmology found that visual impairment (which includes problems such as difficulty seeing at a distance, problems seeing up close, or problems with contrast sensitivity when not wearing glasses) was linked to a higher risk of dementia in adults who were 70 years of age and older. And the more vision problems a person had, the higher the risk seemed. This builds on what doctors and researchers already know about dementia and vision problems: that vision problems and dementia are more likely to occur in older people, that dementia can sometimes affect the ability to a person to see or process what they see, and that there is a relationship between vision problems and dementia.
But do vision problems directly lead to dementia? According to Dr. Ronald Benner, president of the American Optometric Association, it is important to distinguish between visual acuity, which is the sharpness with which you can see objects, and vision in general, which is the how we process sensory information, to get the full picture. any link between dementia and vision.
We normally think of vision as “just the eyes,” Benner said, “but it’s really the visual system, it’s the eyes that collect information and then the brain processes it.”
“Acuity is just one measure of vision,” he added. “We don’t want to confuse that with ‘I have visual loss, I can’t read the smallest letter on the line, ‘I have dementia.'”
Vision is also a way of connecting us to the world and receiving sensory information. And according to Heather Snyder, vice president of medical and scientific relations at the Alzheimer’s Association, this is just one aspect of the sensory health associated with dementia. Other changes in the way the brain processes information – through our hearing, touch and even our sense of smell – have also been linked to cognitive decline. Snyder pointed to research presented to the Alzheimer’s Association in 2019 linking multiple sensory impairments to dementia risk in older adults.
“At this time, these connections are all associations — we don’t know if there’s cause and effect,” Snyder said in an email. “Further research is needed to understand why or how visual impairment is associated with brain health.”
How sight works and how it can overlap with dementia symptoms
In summary, our eyes work by capturing light passing through the cornea and lens and then focusing it; the light eventually reaches the retina, which contains cells that convert light into electrical signals that return to the brain via the optic nerve. People with visual impairment due to myopia, for example, experience disruption of this process because of the eyeball itself, and this can be corrected with glasses or contact lenses.
Other eye health issues, such as cataracts, can also impact sight but require surgery to treat. Research in 2021 found that people who had cataract removal surgery had a lower risk (30%) of developing dementia than those who did not have cataract removal.
Dementia itself can also impact vision if it affects the part of the brain responsible for visual processing. Additionally, certain health conditions that affect other parts of the body may be seen first in the eyes, such as diabetes and high blood pressure (which, coincidentally, have also been linked to dementia risk).
The prevalence of vision problems in the elderly and patients with dementia can make it difficult to know if a person with dementia is having trouble recognizing someone because of the dementia or because their eyeglass prescription is very outdated.
But is there a strong enough link between vision loss and dementia to suggest that keeping your eyes healthy will prevent dementia? According to Dr. Andrea An, medical director and chief neurologist at the Neurology Associates Neuroscience Center in Arizona, there is no clear data linking cognitive health to visual health, adding that preserving vision is “a question full of uncertainties”.
“That being said, the effects of dementia can be more severe if there is associated vision loss,” An explained in an email. “Impaired vision can cause far more disorientation and confusion.”
It can also make a person’s dementia symptoms appear worse than they actually are if they’re unable to see well, she noted.
Snyder noted that vision problems could impact the results of a dementia symptom test, as many rely on sight to perform them.
“Especially as one gets older, this is an important discussion to have with your health care provider to ensure any type of testing is done correctly and efficiently,” she added.
Vision as a path of communication and connection
Social isolation has been identified as a risk factor for dementia. If a person cannot see well, they may give up activities they previously enjoyed. This can lead to symptoms of depression or anxiety, which are risk factors for cognitive decline, Snyder said.
“Poor vision can lead to withdrawal from these activities, and social isolation is known to increase the risk of depression and anxiety,” she said.
Dr. RJ Tesi, CEO and Chief Medical Officer of INmune Bio, a clinical-stage immunology company, said in an email that studies have suggested that mental and social activities can delay cognitive decline, which would include “brain exercises” such as reading, games. and crosswords.
If poor vision prevents you from doing these things, Tesi said, “then it’s very difficult to suggest that poor vision contributes to dementia.”
Up to a quarter of people aged 65 and over can be considered socially isolated. This means that the relationship between social isolation and vision problems may have even more impact. For example, in some cases, a person may know they have a vision problem, but they have no way to correct their vision because they have no one to take them to the eye doctor or because ‘she doesn’t see the point of it.
Hearing is closely linked to our ability to speak and communicate, and loss of communication can “negatively impact cognition and overall health,” Snyder said. But more research is needed to see if there’s a similar link between vision and cognition, she said. Research has recently supported the need to treat hearing loss with a hearing aid to reduce the risk of dementia.
Correcting Your Vision Benefits Your Overall Health
While there are other considerations to discuss with a doctor before recommending an older person have eye surgery, for example, to potentially reduce the risk of dementia, there’s no reason why you shouldn’t shouldn’t stay up to date on your eyeglass prescription or avoid your annual eye exam. exam.
Benner stressed the importance of regular eye exams. In addition to the potential cognitive benefits of correcting your vision, a doctor may be able to detect other health conditions, such as high blood pressure, diabetes, and stroke. Full annual exams are recommended for older people, but anyone who has difficulty seeing or has a prescription for glasses or contact lenses should be checked regularly.
“Often the eyes manifest initial diseases in the body,” Benner said. “It’s very important that people benefit from their routine eye care.”
Learn more: Get affordable eye exams and glasses without insurance