Research connects vision to a later dementia diagnosis.
Scientists found visual sensitivity tests could predict dementia up to 12 years before it was diagnosed.
Neurologists say more work is needed before this is used for early diagnoses of the disease.
The eyes are directly connected to the brain, allowing you to quickly process everything that you see. But that close connection may also indicate subtle signs of dementia, allowing for early interventions.
That’s the major takeaway from research published in the journal Scientific Reports. Given that almost 10% of American adults aged 65 and up have dementia, and future rates are expected to increase, this is crucial information for doctors to explore.
Meet the experts: Clifford Segil, D.O, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA; Bavand Youssefzadeh, D.O., an ophthalmologist at Global Lasik and Cateract Institute in Huntington Beach, CA.; and Amit Sachdev, M.D., M.S., medical director in the Department of Neurology at Michigan State University
But the vision changes linked with dementia are specific and more involved than needing to update your glasses prescription. Here’s what the research found, plus what doctors want you to know.
What did the study find?
For the study, researchers followed 8,623 healthy people in Norfolk, England, for several years. At the end of the study, 537 participants had been diagnosed with dementia.
At the beginning of the study, the researchers asked participants to take a visual sensitivity test, which measures visual processing speed (i.e. the time it takes the brain to analyze and judge something visual). During the test, the participants were asked to watch a screen and press a button as soon as they saw a triangle form in a field of moving dots.
The researchers discovered that participants who eventually were diagnosed with dementia—up to 12 years later—saw that triangle forming slower than those who weren’t eventually diagnosed with the condition.
“Combining visual processing tests with other neuropsychological tests could improve the identification of future dementia risk,” the researchers wrote in the conclusion.
Why might visual sensitivity be linked to dementia?
Again, it’s important to point out that this is more complex than getting glasses or a stronger prescription. “This is not anything that gets corrected with glasses,” says Clifford Segil. D.O., a neurologist at Providence Saint John’s Health Center in Santa Monica, CA. “It’s about memory and recall.”
But there are a few potential things that could be behind having slower visual sensitivity and developing dementia. One is that amyloid plaques (proteins that clump together often found in people with Alzheimer’s) may impact areas of the brain associated with vision first before impacting memory, the researchers explained in a press release. As a result, these changes may show up during a visual test first.
Dementia can also impact the ability to see contrast and to tell the difference between similar colors, the researchers pointed out. Previous research has found that people with dementia have trouble ignoring visual distractions when looking at something, which can cause eye movement issues, too.
Essentially, dementia may impact multiple areas of vision—and these signs could show up before memory problems surface.
But vision is not something doctors commonly focus on when it comes to dementia prevention and screening, Dr. Segil says. Instead, hearing is often addressed, given that research has found using hearing aids can slow cognitive decline in people who are at high risk of developing dementia.
“We routinely try to send people for hearing tests, but we don’t send them for new glasses,” Dr. Segil says. Still, Dr. Segil stresses that this test looks more at visual processing issue—that is, it’s how the brain interprets what the eyes see.
Is this part of typical eye exams?
As of this moment, no. “The main things we look for are signs of high cholesterol, diabetes, and hypertension, among other health-related issues that can exacerbate or [raise the risk of] dementia over time,” says Bavand Youssefzadeh, D.O., an ophthalmologist at Global Lasik and Cateract Institute in Huntington Beach, CA.
But Dr. Youssefzadeh says that visual sensitivity tests may become more common in eye care settings over time and with more research. “I do think it’s going to be an area we explore more in the future,” he says.
Other signs of dementia
Dementia is usually thought of as a problem with memory, but there are different kinds of memory, points out Amit Sachdev, M.D., M.S., medical director in the Department of Neurology at Michigan State University. “The early signs of dementia are based on the kind of memory that is first affected,” he says.
These are considered some of the more common symptoms of dementia, according to the National Institute on Aging (NIA):
Experiencing memory loss, poor judgment, and confusion
Trouble speaking, understanding and expressing thoughts, or reading and writing
Wandering and getting lost in a familiar area
Trouble handling money responsibly and paying bills
Repeating questions
Using unusual words to refer to familiar objects
Taking longer to complete normal daily tasks
Losing interest in normal daily activities
Hallucinating or having delusions or paranoia
Acting impulsively
Not caring about other people’s feelings
Losing balance and problems with movement
Dr. Segil says he most commonly looks for problems driving and issues with finances. “When people start getting lost, getting tickets, or having problems with their finances and making mistakes, those are two things I worry about clinically,” he says.
Dr. Segil calls the latest findings “interesting,” but stresses that visual sensitivity needs to be pursued more to see how this can help patients in real life. “We need a lot more work around this area,” he says.
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