A recent study published in Scientific Reports assessed whether slower visual processing could help identify populations at risk of developing dementia years before symptom onset.
Give me some background first.
Traditional screening tools like the Mini-Mental State Exam (MMSE), Montreal Cognitive Assessment (MoCA), and Hopkins Verbal Learning Test (HVLT) have long been used to assess memory and overall cognitive function in individuals at risk for dementia.
However: While these tools remain essential, recent research has begun to explore additional early indicators.
- One area of growing interest in recent years: visual processing speed.
Talk about this.
Visual processing refers to how quickly and accurately someone can interpret visual information.
How it’s measured: Via the Visual Sensitivity Test (VST), a standardized assessment tool that measures basic processing speed as well as simple and complex motor response time in individuals.
Interestingly: Visual processing is often one of the first abilities to decline in individuals with dementia.
- In fact: Previous research has linked slower reaction times and visual impairments, such as reduced contrast sensitivity or visual sharpness, with increased risk for cognitive decline.
With that in mind: This study examined whether a simple visual test could help identify individuals who may be more likely to develop dementia in the future.
Now, talk about the study.
Researchers analyzed data from a large, long-term health study in the United Kingdom known as the European Prospective Investigation into Cancer (EPIC)-Norfolk study.
Their focus: Whether visual processing speed, measured by the VST, could predict dementia risk.
- They also compared its effectiveness to two established cognitive tests: the HVLT and the Short Form Extended Mental State Exam (SF-EMSE).
Go on …
The VST used in this study came in two variations:
- Simple VST: participants respond to a single visual cue as quickly as possible.
- Complex VST: participants respond to a specific shape that appears among distracting, moving patterns. This is a task that engages visual attention and spatial processing.
The goal: To determine whether slower reaction times on these tests were linked to a higher likelihood of developing dementia in the future.
Talk about these participants.
The study included 8,623 participants from the third health check of the EPIC-Norfolk cohort, aged 48 to 92 and mostly White (99.7%).
Over a median follow-up of 9.8 years, 533 were diagnosed with dementia based on hospital records and death certificates.
- Along with cognitive assessments, most participants also reported their education, physical activity, general health, and medical history.
Findings?
Researchers found that slower performance on both the simple and complex VST was linked to a higher risk of developing dementia.
The data: Participants with low scores on the simple VST had a 39% increased risk, while poor performance on the complex VST was associated with a 56% higher risk.
- Despite these associations, the HVLT proved to be the most reliable predictor of dementia, followed by the SF-EMSE.
And while the VSTs weren’t as strong as traditional cognitive tests in predicting dementia, the complex VST showed greater sensitivity to several known risk factors—including older age, lower education, diabetes, and visual impairments.
- These associations remained significant even after accounting for age, gender, and education level.
Tell me more.
The complex VST added a unique assessment by capturing a broader view of the participant’s overall health and function, not just their cognitive ability.
Its score was related to factors such as poor personal health rating and lower levels of physical activity, both of which have been associated with a higher risk of developing dementia in previous research studies.
What this suggests: The complex VST may be detecting early functional changes that other cognitive tests overlook.
Which translates to …
While it isn’t the most accurately predictive tool on its own, the study authors concluded that VST could serve as a useful addition to standard cognitive assessments, helping to identify individuals at risk through a wider lens.
Limitations?
- Lack of diversity in the sample, with 99.7% of participants identifying as white
- Reliance on self-reported health and vision data, which may not always be accurate
- Possible underrepresentation of individuals with more severe cognitive or physical impairments
- Lower-than-expected accuracy of the VST, possibly due to inconsistencies in how the test was administered or recorded
Expert opinion?
Although the VST didn’t outperform traditional memory tests like the HVLT, experts highlighted its prospective value as part of a collective screening approach.
The authors’ conclusion: The VST is quick, easy to administer, and less dependent on language or education level, which makes it accessible to a wider range of people.
- When combined with tests like the HVLT, it can help provide a more complete view of a person’s dementia risk and could help catch early changes that might otherwise go unnoticed.
So how does this compare to previous research?
Other research studies, including findings from the Sydney Memory and Aging Study, have shown that visual reaction time tests can be just as effective as traditional cognitive tools in detecting early signs of dementia.
- When combined with verbal memory assessments like the HVLT, their accuracy improved, making it easier to identify individuals at risk.
As such: Using this method could improve early detection of dementia, giving patients a better chance at timely intervention. And because the VST is straightforward and easy to administer, it can be a useful tool in everyday clinical practice.
Take home.
Visual processing speed, especially when measured using the complex VST, demonstrated strong potential in identifying dementia risk. While it’s not necessarily a replacement for traditional memory tests, it can provide valuable insight when used alongside them.
As a result: Including the VST in cognitive assessments may improve early recognition by capturing both cognitive changes and broader risk factors—leading to earlier intervention and better care for those at risk.