Eye Screening Could Help Detect Alzheimer’s Early
By Kylie Wolfe
A preliminary study published in JAMA Ophthalmology suggests a new method for detecting Alzheimer’s disease decades before patients experience symptoms. Using an instrument already found in many ophthalmologist’s offices, doctors may be able to arrive at an early diagnosis by examining patients’ retinas for disease-associated structural changes.
A Progressive Disease
Each year, roughly 500,000 people are diagnosed with Alzheimer’s disease in the United States alone. In the years prior to their diagnoses, patients accumulate large amounts of abnormal protein deposits in the brain known as plaques and tangles that ultimately interfere with neuronal communication. At first, these microscopic changes don’t produce noticeable symptoms, but as the disease progresses, the proteins cause permanent damage, leading to cell death and worsening symptoms.
Usually, diagnosis doesn’t occur until the patient demonstrates memory loss or behavioral problems, at which point the disease has been affecting the central nervous system for a number of years. The ability to screen patients early may be the key to predicting and possibly preventing further neurodegeneration.
Preventative Measures
Current methods for early diagnosis are expensive and invasive, but researchers may have found a promising alternative that’s quite the opposite. For the published study, a group of 32 people not previously diagnosed with the disease were examined using PET scans, cerebrospinal fluid analyses or both to test for relevant biomarkers. Results revealed elevated levels of abnormal proteins in 14 of the participants, leading researchers to diagnose them with preclinical Alzheimer’s disease.
Then, using optical coherence tomography (OCT), the same technique used to screen for macular degeneration, glaucoma and other retinal diseases, researchers added an angiography component (OCTA) to look for blood flow patterns. They examined each person’s retina and optic nerve for physical differences like varying retinal thickness and vascular networks and found that those diagnosed with the disease had larger foveal avascular zones at the centers of their retinas. This area naturally lacks blood vessels, but the increased size suggests even fewer blood vessels and therefore a decrease in blood flow.
The ability to detect these physical changes by expanding the capabilities of a common test could make OCTA a viable screening option for Alzheimer’s disease. It’s both inexpensive and non-invasive, making it accessible to a larger number of patients.
Future Possibilities
The results of this study support previous findings of structural changes in the retina and optic nerve of Alzheimer’s patients. While these results are promising, researchers caution that more studies are needed. Ultimately, the connections between our eyes and brains may offer a glimpse into the future for some, allowing doctors to begin treatments sooner.
