Vision and Cognition: A Recent Study
A recent study published in JAMA Network Open, for example, followed individuals aged 60 to 94 whose vision and cognition were tested every one to four years for a span of approximately seven years. Researchers concluded that those whose vision scored poorly initially were more likely to experience problems with memory, attention, and other cognitive functions over time. To be clear, if you're born with a visual impairment or developed one earlier in life, your brain is able to adapt due to a phenomenon known as neuroplasticity, which is a type of flexibility that allows for growth and change, says neurologist Faye Begeti, MD, PhD. But neuroplasticity declines with age, she adds, which is why later-onset vision loss can lead to cognitive decline. (More on that in a bit.)
What Is Neuroplasticity?
In layman’s terms, neuroplasticity is the “brain’s ability to adapt, create, and regenerate in response to life’s events,” says neurosurgeon Bowen Jiang, MD.
“In utero developing brains are undergoing massive neuroplasticity—changes—starting from a single fertilized egg to a well-developed newborn brain,” explains Stanford University forensic neuropsychiatrist Octavio Choi, MD, PhD, providing an example of neuroplasticity. “Less dramatic examples would include learning (if you study something today, and remember it the next day—the reason is because studying induces structural changes in the brain, [lending to] an encoded memory).”
Learning doesn’t only incorporate memorizing fun facts, though. “On the extreme side of the spectrum, recovering from stroke, brain tumor surgery, or spinal cord injury and eventually regaining neurological function are all excellent examples of the marvels of neuroplasticity,” says Dr. Jiang, sharing another example.
The key to maintaining neuroplasticity is to keep your brain active. “Neuroplasticity is induced by neural activity—brain cells firing,” says Dr. Choi. “When a firing brain cell is able to induce firing of other brain cells in a circuit, that circuit tends to become stronger (physical connections between those cells develop)—‘Neurons that fire together, wire together.’”
The Correlation Between Vision Loss and Decline in Cognitive Function
While the exact cause-and-effect relationship is still being investigated, Dr. Begeti says there are a few reasons for the correlation between the eyes and brain (and between vision loss and a decline in cognitive function). "Conditions such as diabetes and high blood pressure affect blood vessels to both the brain and eyes, leading to cognitive impairment and visual loss concurrently," she says. In other words, the same health issues that damage vision also damage cognition, so it makes sense that both would occur in the same individuals.
Neurologist and Brain Wash author David Perlmutter, MD agrees with this hypothesis, noting that the eye, and specifically the retina, does not respond well to issues like poor blood supply, damage to the arteries, inflammation, and a process called oxidative stress, whereby free radicals overwhelm the body's ability to protect against them. And the brain, he says, is negatively impacted by these issues as well.
Dr. Choi adds to this noting that “the basic cellular mechanisms for age-related degeneration break down into oxidation, glycosylation, and inflammation.” All three of things contribute to vascular damage over time, which leads to impeded vision and cognitive function. “As the small arteries get clogged, eventually small bits of the retina/brain die (as a result of micro-strokes)—leading to degeneration,” he explains. “That’s why it’s so important to slow down atherosclerosis, or plaque-filled arteries.” With that in mind, he says that treating high blood pressure, keeping blood sugars in a healthy range, and adopting an anti-inflammatory diet are all means for preventing and mitigating both cognitive and vision decline.
Degenerative Cognitive Diseases
The eye-brain connection is strong and, as such, can heavily impact one another. According to Dr. Perlmutter, degenerative cognitive diseases, such as Alzheimer's, are classified as inflammatory diseases, meaning they are caused, in part, by inflammation in the brain. "So anything in the long run that can allow inflammation to smolder [e.g. poor diet, lack of exercise, and other lifestyle choices] will cause a decline in vision and will similarly affect the brain," he says.
As for other lifestyle choices, Dr. Jiang says that isolation—like, say, during a pandemic—can speed up both vision and cognitive decline. “Visual loss is not just a physiological or a biological illness, but rather a psychosocial one,” he explains. “Societal and environmental isolation can have detrimental effects on both physical and mental wellness.”
In that way, the eye-brain connection is a bit of a never-ending circle, for what causes cognitive decline can lead to visual decline and vice-versa. "There are many resultant negative consequences of visual loss such as social withdrawal, reduced physical activity, and depression, all of which are independent risk factors for developing dementia," says Dr. Begeti.
Dr. Choi expands on this, noting that, “Depression can result in decreased physical as well as mental activity; there are also specific biological pathways in depression which cause brain decline—such as reduction in brain growth factors in the areas of the brain such as the hippocampus (one of the main memory centers in the brain).”
Suffice to say, when your vision or cognition begins to decline, your brain and your eyes are forced to work harder to process things, which further impacts their decline. Dr. Begeti explains that while mental stimulation is good for the brain, this form of hard work is not. She likens it to walking more when you have an injury that makes it hard for you to walk—all you're doing is exacerbating the injury.
Thankfully, there are ways to strengthen and cater to the eyes and brain. And doing so will help to avoid brain eye connection problems. Because, newsflash, degeneration doesn’t affect everyone the same way.
How To Manage and Prevent Brain-Eye Connection Problems
First and foremost, if you notice that your vision is declining, Dr. Choi says that it’s imperative to schedule an appointment with your doctor(s). “Many of the causes of [brain eye connection problems] are reversible, and getting your visual health checked can uncover problems that lead to both visual, as well as brain decline (e.g. diabetes, hypertension).” In that way, Dr. Choi says that visual decline can be a “canary in the coal mine” for overall brain health—so don’t ignore it.
Another thing you shouldn’t do? Worry about the possibility of degeneration. After all, it's important to note that this is not the sealed fate of every elderly person. Dr. Perlmutter insists that making healthy lifestyle choices throughout your life can significantly reduce your risk for the issues that cause vision loss (and potential cognitive degeneration). As proof, he points to a study published in the Archives of Ophthalmology that showed that giving zinc and antioxidants to elderly people with age-related macular degeneration (an eye disease causing vision loss) helped them preserve their vision.
Another thing you can do? Be social! “Much of our brain is devoted to social processing: interpreting the behavior of others, or mentalization, conversing, and emotional attunement,” says Dr. Choi. “Staying social keeps our brains active, which keeps it healthy. [After all] brains are kept healthy with use, just like the other excitable tissue we are familiar with (ie. muscles). ‘Use it or lose it.’”
Dr. Perlmutter calls this knowledge "empowering," and says that while it's true that the same mechanisms that damage vision impact cognition, it's within our control to avoid both forms of deterioration. "Our lifestyle choices have a huge role to play in whether we're going to be intact cognitively when we're 85," he says. "You've got to exercise, you've got to have nutritious food—and what that means is more plant-based, higher fiber—and you've got to do all of the other things to reduce inflammation in your body like getting enough sleep, reducing stress, and getting out in nature. These things work.”
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