If you’re over 40, you know: Eyesight deteriorates with age. Why? The lenses of our eyes become less flexible over time, which can lead to unfocused vision. Glare likely bothers you a lot more now, making driving at night more difficult. You might need more light for reading. If you have cloudy or blurred vision, however, your vision changes might be more serious than simple aging. Cataracts occur with higher incidence in those over 40, and recent research shows why it’s more important than ever to get them treated: Having cataract surgery could significantly lower the risk of developing dementia.
Even if you’re not affected by cataracts right now, that may change as you age. The National Eye Institute reports that more than half of Americans age 80 and older either have cataracts, or have already had cataract surgery. In addition, the study – written by University of Washington researchers and published in JAMA Internal Medicine – notes that sensory impairment (like vision loss) could increase dementia risk.
The Link Between Cataract Surgery and Dementia
In their paper, the study authors say nearly 50 million people worldwide suffer from some form of dementia, and that no effective treatments currently exist. Thus, finding ways to reduce or delay its onset is crucial.
Previous research shows that visual impairment increases the risk of dementia. With this in mind, the investigators conducted an extensive analysis of data from the Adult Changes in Thought (ACT) study — an ongoing study that tracks participants’ brain health from 65 years old onward.
All participants were dementia-free when they enrolled in the ACT study. Every two years, the ACT team followed up with them and noted if and when they developed dementia. The team classified forms of dementia as either general dementia, Alzheimer’s disease, or Alzheimer’s and related dementia.
In order to establish a link between cataract surgery and dementia, the researchers from Washington focused on participants who had cataracts or glaucoma. (Why did they test out glaucoma as well? They wanted to know whether visual impairment caused by glaucoma also increased dementia risk.)
In total, the researchers’ analysis included data from over 3,000 participants with cataracts. They found that participants who had cataract surgery were 30 percent less likely to develop dementia from any cause, as compared to participants with cataracts who did not have surgery. In addition, cataract surgery was linked to a lower risk of dementia caused by Alzheimer’s. (Glaucoma surgery wasn’t linked to a significant change in dementia risk.)
“This kind of evidence is as good as it gets in epidemiology,” lead researcher Dr. Cecilia S. Lee, associate professor at the University of Washington School of Medicine, said in a press release. “This is really exciting because no other medical intervention has shown such a strong association with lessening dementia risk in older individuals.”
Why might cataract removal reduce your risk of dementia?
While the researchers couldn’t confirm why cataract removal was linked to a lower risk for dementia, they have their theories. One idea is that sensory input – like the information we receive and process from our eyes – is crucial to brain health. If our brains get less “visual exercise,” they become more susceptible to neurodegeneration: when the neurons in the brain deteriorate, stop forming new connections, and die out.
In addition, the research team suspects that visual impairment limits people’s activities. Limitations can cause them to withdraw from social interactions, exercise less, and become isolated, which can lead to depression and cognitive decline.
So, what’s the takeaway? If you suspect that you have cataracts, it’s extremely important to get in touch with your optometrist or ophthalmologist. And if you don’t have cataracts, you still need to take care of your eyes. Visit your eye doctor annually to check for abnormalities and ensure your eyes are in good health. Your mind depends on it.