Eye Exams Could Soon Detect Alzheimer’s Disease

Predicting Alzheimer’s Cheaply and Simply

According to researchers at the University of California’s San Diego School Of Medicine and at the Washington University School of Medicine, cognitive tests may soon offer a low-cost, minimally invasive, and simple method of screening people for the genetic risk of Alzheimer’s disease. According to both recently published studies, the speed at which a person’s pupils dilate and other ophthalmic indicators could be the key to this early detection, even when there are no other symptoms of the disease present.

Detecting Alzheimer’s Is Not a Simple Process

Discovering Alzheimer’s before cognitive decline begins is a challenging task. The disease begins to drastically change and damage the brain several years before any symptoms start to appear in the individual suffering from it. Medical professionals currently only have the option to use invasive methods such as spinal taps or costly positron emission tomography (PET) scans to help diagnose Alzheimer’s. Even after going through the discomfort and expenditure, a diagnosis can only be confirmed with certainty once the person has passed away and signs of the disease are found in the brain. Millions of people around the world may be living with the dreaded disease, and the numbers are increasing every year. If a routine eye test can predict Alzheimer’s years before any symptoms begin to appear, medical professionals would have better prospects of using medical applications that could slow the progression of the disease.

Research Findings

Over the years, scientists who are researching the pathology of Alzheimer’s disease have mainly been concentrating on what causes and contributes to it. Substantial time and effort have been invested in the research of tangles of a protein called tau as well as protein plaques that accumulate in the brain and are known as amyloid-beta. Both are known to have a profoundly damaging effect on neurons and to result in cognitive decline. Scientists have found that these Alzheimer’s-related plaques can begin to amass in the brain as early as two decades before any symptoms appear.

In more recent research, the focus has shifted to pupillary responses. Driven by a cluster of neurons in the brain stem responsible for modulating cognitive function and regulating arousal, these cognitive responses are closely linked to Tau, the earliest known biomarker for Alzheimer’s disease. As cognitive tasks are processed, the diameter of the eyes’ pupils change. The more difficult the task is, the larger the pupils become. In previous research, it was revealed that adults who are mildly cognitively impaired display greater cognitive effort and increased pupil dilation in comparison to individuals who are cognitively normal. Mild cognitive impairment may be a precursor to the onset of Alzheimer’s. Researchers from the University Of Washington School Of Medicine also discovered that there is a link between Alzheimer’s disease and three degenerative eye diseases—glaucoma, diabetic retinopathy, and age-related macular degeneration.

Practical Applications for Research Findings

Unlike the brain, the retina is accessible and is thus an ideal area to use in medical diagnosis. It is interconnected with the central nervous system so changes in the brain may be reflected in the retina’s cells.

By adding a procedure called optical coherence tomography angiography (OCTA) to a standard eye exam, doctors can distinguish between red blood cells and other tissue in the retina of the eye that allows a view of blood-flow patterns. In patients with Alzheimer’s, it was found that the area at the center of the retina without blood vessels was significantly larger, which suggests that there is less blood flow. Using this method also makes it possible to notice a thinner retina layer and fewer small retinal blood vessels in the back of the eye, both of which are possible indications of Alzheimer’s disease. In previous studies, researchers have discovered that the eyes of deceased Alzheimer’s sufferers showed signs of optic nerve degradation and thinning of the retina.

Should it be successfully developed, the method has the potential to be a screening tool that helps decide whether somebody should undergo more invasive and costly testing before any clinical symptoms begin to appear. It is also believe that this will help medical professionals to formulate a better understanding of who is amassing abnormal proteins in their brains that may result in the development of Alzheimer’s disease.

What’s Next?

Dr. Gregory P. Van Stavern is a co-investigator in the research program and a professor of ophthalmology and visual sciences at Washington University. He said that using an eye exam to predict Alzheimer’s is a promising endeavor, but that it is still too early to tell whether this method will be able to detect the disease early enough to effectively slow the progression of cognitive decline. According to Stavern, we could be between five and 10 years from completing the development of an affordable diagnostic tool that can be simply added to routine eye exams.

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