Eye tracking and Alzheimer’s: How to tackle early diagnosis

New Alzheimers medications are promising, but now the emphasis is on early diagnosis — eye tracking may have the answer.

Scientific advancements are truly on the cusp of ushering the next era in Alzheimer’s treatment, as new drugs that slow down progression of the disease begin to hit the market. 2024 was a pivotal year in the development and approval of Alzheimer’s drugs like Lecanemab and Donanemab which already offer measurable slowdown in memory and thinking decline.

While these drugs hold the potential to slow disease progression, they rely on catching the Alzheimer’s in its early stages; today, identifying Alzheimer’s early remains a challenge. Enter eye tracking: a noninvasive, cost-effective tool that is reshaping the way we approach early Alzheimer’s assessments.

Early diagnosis and eye tracking

Alzheimer’s disease, a neurodegenerative condition responsible for 70% of dementia cases, progresses silently long before symptoms manifest. Current diagnostic methods, including lumbar punctures and neuroimaging, can be invasive, expensive, and time-intensive, making them inaccessible to many. Eye tracking has begun to enable a practical alternative, utilizing subtle changes in eye movements to detect cognitive decline.

Let’s explore how this technology works and its potential to transform early Alzheimer’s screening.

The connection between Alzheimer’s and eye movements

Alzheimer’s affects the brain regions responsible for controlling eye movements, leading to detectable changes even in early stages. Here are four ways eye tracking can aid early diagnosis:

1. Fundamental eye movement assessment

Basic tasks, like focusing on a static dot or following a moving target, can reveal Alzheimer’s-specific patterns. For instance, individuals with Alzheimer’s often:

• Struggle to maintain stable fixation.
• Exhibit more frequent, involuntary eye movements (e.g., square-wave jerks).
• Perform poorly in tasks requiring quick, precise eye movements toward a target.

Studies have shown these simple tests can distinguish individuals with Alzheimer’s from healthy peers with up to 95% accuracy.

2. Executive function evaluation

The antisaccade task, which measures a person’s ability to inhibit reflexive eye movements, is another promising approach. Healthy individuals typically make errors in 20% of trials, whereas those with Alzheimer’s error rates range from 50-80%. These results not only differentiate Alzheimer’s patients but also correlate with disease severity.

3. Advanced visual behavior analysis

Eye tracking reveals difficulties in tasks like visual search and scene exploration among Alzheimer’s patients. These challenges stem from memory deficits and impaired attention:

• During visual search tasks, individuals take longer to locate targets and display disorganized search patterns.
• In recognition tasks, they struggle to differentiate between familiar and novel images, a potential early indicator of cognitive decline.

4. Reading behavior monitoring

Reading, a complex cognitive task, can be revealing. Changes like longer fixation durations, more frequent re-reading, and slower reading speeds are common in Alzheimer’s. Eye tracking during reading tasks has demonstrated nearly 90% accuracy in identifying Alzheimer’s patients, highlighting its diagnostic potential.

Eye tracking in the era of new treatments

While groundbreaking treatments are closer than ever, these medicines emphasize the importance of early detection. Eye tracking offers a practical and scalable solution for primary care settings, enabling widespread, noninvasive screening. With eye tracking we get:

• Accessibility: Quick, language-independent tests.
• Comfort: Remote, head-free tracking suitable for elderly individuals.
• Cost-effectiveness: Affordable compared to traditional diagnostic methods.

With continued research, eye movement metrics may become reliable biomarkers for Alzheimer’s, complementing emerging therapies and existing diagnostic tools. As we stand on the brink of a new era in Alzheimer’s care, technologies like eye tracking hold immense promise in improving lives through earlier intervention and diagnostics.