Alzheimer’s, the dementia which already raids the lives of over 5 million Americans and is contemplated to soar the number of victims by up to 3 times over the next 3 decades, has no cure.
In the face of this growing worldwide epidemic of Alzheimer’s, there is a dire need for diagnostic tests that will identify the risk of acquiring it much earlier in the disease process.
The challenge lies in finding out a consistent abnormality in the formation of brain proteins that signals the disease’s emergence.
Amyloid plaque is a key marker for Alzheimer's disease.
A fully manifested Alzheimer’s is marked by aggravated amyloid plaques and tangles that destroy the neurons and hamper the communication between them. However, unfortunately, the tangles and plaques are usually seen on autopsy after the patient’s death. Although PET scans of the brains can be done to detect the accumulation of amyloid and tau proteins, they are not only expensive but also involve an invasive procedure of injecting the patient with radioactive tracers that bind with the indicative proteins and glow during the scan.
Hence, arises the need for timely detection of these amyloid proteins (before they start growing and accumulating) to effectively diagnose the condition in its initial stages.
"The retina is not just connected to the brain, it is a part of the central nervous system."
The researchers have been lately exploiting the eye as a developmental outgrowth of the brain. The retina and brain undergo similar changes due to Alzheimer's, so the eye serves as an easily accessible window to monitor the disease’s progression.
Optical Coherence Tomography (OCT)
The simple, non-invasive test involved examining retinas through a camera to detect changes in the pattern of light reflection as early stages of amyloid gathering. The cameras were fitted with special software to note the width and other characteristics of blood vessels in the retina.
A flickering light shone on the retina of healthy subjects caused immediate dilation of arteries and veins, while for those suffering from Alzheimer’s disease, retinal arteries and veins had a delayed reaction to a flickering light test.
The findings of the OCT scans established that the difference in the widths of certain blood vessels in diseased people directly corresponded to the quantity of plaque observed in the PET scan of their brains.
This makes the OCT technique a promising screening tool for preclinical Alzheimer's, as it can be performed at any ophthalmologist clinic.
References:
- Eye Test Spots Alzheimer's Before Symptoms
- Health Buzz: A Simple Eye Test Could Help Diagnose Alzheimer's Disease
- Simple Eye Tests to Detect Alzheimer's Disease in the Works
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