Is There A Link Between Dementia and Eye Health?
The World Health Organization (WHO) estimates more than 55 million people have dementia worldwide. The report by WHO further states that there are nearly 10 million new cases of dementia every year. While dementia results from various diseases and injuries that affect the brain, several other studies have revealed a close relationship between eye condition and memory loss.
WHO ranks Alzheimer’s disease as the most common form of dementia contributing to 60–70% of cases. Dementia is strongly associated with old age though it does not exclusively affect older people. Young-onset dementia, which occurs before age 65, accounts for up to 9% of dementia cases.
Dementia is currently the seventh leading cause of death globally. It kills more people than prostate cancer. Some risk factors of dementia include depression, social isolation, and cognitive inactivity.
The Connection Between the Eyes and the Brain
Dementia is the progressive loss of cognitive functioning. Dementia patients struggle with memory loss, reasoning, language, and the ability to perform mental calculations. All these cognitive malfunctions occur due to a variety of reasons, although most of them involve irreversible changes to the brain.
The eyes have a light sensory tissue known as the retina. The retina collects light rays and converts them into electrical signals. The optic nerve connects the eye and the brain. The nerve relays these signals to the brain’s visual center for processing and comprehension.
The retina, a critical eye part, is closely connected to the optic nerve. According to ophthalmologists, the retina and optic nerve are formed from brain tissue during development. They form part of the central nervous system. Thus, any slight damage to the related parts of the brain can alter the performance of the optic nerve and retina.
Also, most eye conditions can affect parts of the brain that contribute to vision and visual information processing. You will likely experience poor vision when the system relays and processes visual information and suffers damage.
Relationship between Eye Diseases and Dementia
Old age is the most common and significant factor for many eye disorders and dementia. So, by getting older, the risks of developing vision impairment and dementia increase. Further, several studies show that dementia can lead to vision changes. The dominant explanation for this outcome is that both problems- dementia and eye problems- are typical of aging.
Due to advanced age, eye diseases like age-related macular degeneration also affect vision and increase the risk of developing dementia. Further, other eye disorders that develop slowly from the accumulated damage of intraocular pressure and high blood sugar increase the risk of developing dementia and vision loss.
Thus, it is safe to assume that most vision problems make dementia worse. Eye conditions such as peripheral and blurry vision loss may indicate a rapidly-progressing dementia case. Most of the confusion arising from vision disorders reflects the same early signs of dementia.
These signs could include and not limited to:
- Difficulty recognizing (even familiar) faces
- Getting lost most of the time, even in familiar places
- Frequently misplacing objects
- Loss of memory
How Are the Symptoms Interlinked with Vision Loss and Dementia?
The vision loss and dementia symptoms can become more severe when you fail to notice them or seek treatment early. But the scenario is more difficult because both dementia and loss of vision tend to progress slowly, making it harder to notice the gradual changes.
The more difficult it is to see objects around us, the harder it becomes to memorize and recognize faces – especially those of new friends. As time progresses and both conditions combine, the simple symptoms of poor eyesight, forgetfulness, and memory loss quickly turn into a dementia crisis.
You will ultimately lose what you don’t use, which also applies to vision and memory. So, if you lose your eyesight, the communication between the retina and optic nerves stops, speeding up the brain changes and driving dementia.
Vision loss will slowly lower the amount of information your eyes feed the brain. Losing vision also means having less stimulation from the eyes and breaking down most of the brain’s visual information processes.
Can Dementia Cause Vision Problems?
There might not be a straightforward answer to this question because there are many causes of sight loss in people with dementia.
These causes include:
- Eye conditions such as cataracts or macular degeneration
- Underlying health conditions, such as stroke
- Normal aging of the eye
So, each of the causes of dementia can damage your visual system.
But What of People with Dementia?
Dementia patients, too, experience vision problems because the disease majorly affects the parts of the brain that process visual information coming from the eyes. A dementia patient will therefore experience vision problems even when they have healthy eyes.
Thus, it is often difficult to tell the difference between sight loss symptoms and dementia because one condition may mask the other.
Yet, it may be a sign of problems with your sight if you experience difficulty with any of the following:
- Avoiding obstacles
- Finding things or objects
- Reading from close range
- Locating food on their plate
- Difficulty recognizing people
- Discomfort with low light, bright light or both
- Problem with seeing well, even with glasses on
Most of these issues arise because of dementia and may worsen because there’s always a gradual impact on the eyes. If you have poor vision, you may have greater difficulty reading. It means you may read less often, further decreasing your brain stimulation.
“This type of decrease in sensory and cognitive input may accelerate cognitive decline,” says Brendan Kelley, MD, cognitive and dementia researcher and professor at UTSW Medical Center.
Dementia patients experience different symptoms depending on the underlying cause. The most common symptoms are difficulty with memory, communication, and cognitive abilities. And while different types of dementia have specific causes, each of these cases relates to the degeneration of brain tissue and visual loss.