Scientists report that they have detected evidence pointing to Alzheimer’s in patients who showed no prior symptoms of the disease. However the most interesting part is that, this was done using a noninvasive test — through the eye.
It’s also equally amazing that the tests were done using equipment similar to those already being used at eye clinics.
What this means is that in the near future, it would be possible to screen patients for Alzheimer’s with a simple eye exam.
Testing Alzheimer’s Prior to Clinical Symptoms
“This technique hints a great potential in it, to become a tool that could help screen patients to decide who needs to undergo advanced invasive testing for Alzheimer’s before the disease does more harm to the victim,” explained Bliss E. O’Bryhim, MD, PhD., the study’s first author.
The concept is to use this technique to identify and investigate people who accumulate abnormal levels of protein in their brain that puts them at risk of developing Alzheimer’s.
Even before there are symptoms, research reveals that Alzheimer’s-related plagues can hoard in the brain for as long as 20 years, without a sign. Therefore, what we call symptoms of this condition, like cognitive decline or memory loss in a person are basically damages already caused by the disease.
This is why methods that promise to detect the disease sooner attract funding for deeper research.
Currently, physicians use lumber punctures and PET scans to diagnose Alzheimer’s, but the problem is, these options are invasive despite being expensive.
In different studies, examining the eyes of victims who succumbed to Alzheimer’s, researchers report that their eyes exhibit signs of degradation of the optic nerve, and thinning at the center of the retina.
The New Study
Again, the new technique, also reported in JAMA Ophthalmology, is non-invasive and it’s known as optical coherence tomography angiography,) which makes it cheap from the word go.
This was used to investigate the retinas in eyes of 30 participants in the age bracket of the mid-70s, which none showed any clinical symptoms of the disease.
The results were that, close to half of the tested volunteers had elevated levels of the Alzheimer’s proteins tau or amyloid, as revealed by cerebrospinal fluid or PET scans. This means despite the absence of symptoms, that group of people had higher risks of developing Alzheimer’s. Cerebrospinal fluid analyses and PET scan tests on the other subjects were normal.
The participants involved in the study were patients who took part in a Washington University’s Memory and Aging Project. In the work, those who exhibited higher levels of tau or amyloid were found with a significant thinning at the center of their retina.
Well, everybody has a small area that has no blood vessels in the center of the retina, the part is responsible for precise vision, but for people with preclinical Alzheimer’s signs, the researchers say the zone lacking blood vessels happens to be significantly enlarged.
The test was executed by shining light into the eye which makes measuring the retina’s thickness and the optic nerve’s thickness possible. For this research, however, the scientists added a new component what they call angiography – this allowed them to tell the difference between red blood cells and other tissues in the retina.
Professor Gregory P. Van MD, visual sciences and ophthalmology says, the angiography component allows the researchers to analyze blood-flow patterns. In patients with preclinical Alzheimer’s the extended area without blood vessels points out a limited supply of blood to the tissues.
The Future of this Technique
Hopes are that, since we already know the pathology of Alzheimer’s, that it begins way before the symptoms show up, doctors would be empowered by an advanced technology of what is currently used for eye tests to fully confirm the disease as early as possible. This would allow early treatment to delay damages like memory loss and cognitive decline.