Gaby
Our eyes reveal a lot about our brain health. New research suggests vision problems can be an early warning sign of cognitive decline.
A recent study from Loughborough University in the U.K. found that reduced visual sensitivity can predict dementia up to 12 years before a formal diagnosis.
What Did the Researchers Discover?
The researchers examined long-term health data from 8,623 people living in Norfolk, England, who were healthy at baseline. By the end of the follow-up period, 537 participants had developed dementia—most commonly Alzheimer’s disease—allowing the team to identify factors that tended to appear before diagnosis.
At the start of the study, participants completed a visual sensitivity test. Volunteers pressed a button as soon as they saw a triangle form within a field of moving dots. Those who later developed dementia were significantly slower to spot the triangle than people who did not go on to develop dementia.
What’s Behind This Connection?
Vision problems can be an early indicator of declining cognitive function. Amyloid plaques linked to Alzheimer’s disease may first affect brain regions involved in vision, with memory-related areas becoming damaged later as the disease progresses.
Alzheimer’s can impair parts of visual processing such as contrast sensitivity (the ability to see object outlines) and certain aspects of color perception—particularly problems with the blue-green part of the spectrum in early stages.
Another early sign is a deficit in inhibitory control of eye movements, where distracting stimuli hold a person’s attention more easily. People with cognitive impairment struggle to ignore distractions, and that can show up as difficulty controlling eye movements.
Difficulties in Face Recognition
The team also reported that people with dementia have trouble processing unfamiliar faces. In other words, they don’t follow the typical scanning pattern of a face during conversation.
Healthy people tend to scan a new face from the eyes down to the nose and mouth to help remember it. Clinicians can often spot people with dementia because they seem confused and don’t move their eyes to scan faces or their surroundings.
As dementia advances, patients find it harder to recognize others because they stop scanning facial features. So difficulty recognizing someone you just met may stem from ineffective eye movements rather than—or in addition to—a memory problem.
Can Eye Movement Improve Memory?
Previous research has been inconclusive, but some studies suggest that eye movements might boost memory. That could help explain why people who read a lot or spend time watching TV often show better memory and a lower dementia risk than those who do not: reading and watching make the eyes move across text or images.
Frequent readers also tend to have more education, and education builds cognitive reserve. That reserve helps protect against symptoms when brain connections start to break down with age.
Despite these hints, deliberately using eye movements to treat memory problems in older adults hasn’t been thoroughly explored. The team says that until cheaper, easier-to-use eye-tracking devices are available, using eye movement as a practical early-diagnosis tool outside the lab won’t be feasible.
