A recent study at Washington University School of Medicine found that an eye test could detect deterioration due to Alzheimer’s disease in older adults who are not yet showing symptoms. The study included 30 patients, and the results were published in JAMA Ophthalmology on August 23.
An eye exam cannot diagnose Alzheimer’s disease, but it could be instrumental in determining who should be tested for the degenerative nerve disorder. Researchers are optimistic that this new technique could help easily identify candidates who may need to be tested.
What is Alzheimer’s Disease?
Alzheimer’s disease is the most common form of dementia. It is characterized by the accumulation of abnormal proteins in the brain. Fifty million people have Alzheimer’s disease and other forms of dementia, and there is currently no cure for the disease.
Protein build-up, or plaque, can collect in the brain for up to 20 years before symptoms begin to appear. By the time Alzheimer’s disease is diagnosed, the plaque has already caused irreversible brain damage.
New Methods to Diagnose Alzheimer’s Disease
PET scan and lumbar punctures are the most common method for Alzheimer’s diagnosis, but they are costly and invasive. The team from Washington University School of Medicine used a noninvasive technique known as optical coherence tomography angiography (OCT-A) to inspect the retinas in the eyes of the participants.
Optical coherence tomography (OCT) is a component of a comprehensive eye exam that is often administered by an eye doctor if there is suspicion of a retinal or optic nerve problem. This test shines light in the eye to allow an ophthalmologist to measure the thickness of the retina and optic nerve.
Past research suggests that Alzheimer’s disease can cause thinning of the center of the retina and the deterioration of the optic nerve, and the new study supported these findings. Patients who had high levels of protein accumulation in the brain also exhibited thinness in the central retina.
Optical coherence tomography angiography, however, is not standard in a comprehensive eye exam. This test allows eye doctors to differentiate between red blood cells and other cells in the retina and analyze blood flow patterns. Study participants with pre-clinical Alzheimer’s had larger central areas of thinness in the retina, which indicated reduced blood flow.
If further studies replicate similar results, a simple eye test could revolutionize how Alzheimer’s disease is detected. Optical coherence tomography angiography could facilitate diagnosis of Alzheimer’s at a stage in which intervention could halt the progression of the disease, although currently there are no medications that slow the disease significantly. Someday, eye doctors may be able to screen patients in their 40s or 50s to assess their risk.
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