by Researchers at the Duke Eye Center have discovered that Alzheimer’s disease and other brain illnesses can be identified through a simple eye exam. By analyzing the retinas of over 200 individuals, the study found significant differences between those with Alzheimer’s disease and those with a healthy brain.
The human eye shares several similarities with the brain, making it a potential window into brain pathology. Due to these similarities, the eye has been recognized as an affordable biomarker for Alzheimer’s disease and other brain-related illnesses. Traditionally, the diagnosis of Alzheimer’s disease is only possible once patients begin to display early cognitive loss. A formal diagnosis is typically made through cognitive or mental state examinations, and confirmation can only be obtained through a postmortem examination of the brain.
Currently, biomarkers such as Aβ-42, T-tau, and p-tau found in cerebrospinal fluid, as well as fluorodeoxyglucose and Pittsburg Compound B found in the brain, are used for monitoring Alzheimer’s disease. However, the widespread implementation of these biomarkers remains challenging.
Visual biomarkers have gained attention in the search for new ways to diagnose Alzheimer’s disease. Studies have demonstrated that certain visual symptoms could indicate the onset of dementia and the development of senile plaques in the brain’s visual regions. Researchers have discovered that structural retinal biomarkers may offer early signs of Alzheimer’s disease. Common vascular issues associated with Alzheimer’s include compromised blood-brain barrier, impaired Aβ clearance, vasoconstriction, reduced blood vessel density, and decreased blood flow.
The direct visualization of Alzheimer’s disease hallmarks in the retina is considered the most promising biomarker due to its specificity for the disease. However, further research is required to confirm the presence of Aβ plaques in retinal tissues and their predictive value for cerebral deposits. In addition, a visual variant of Alzheimer’s disease called VVAD has been identified, affecting relatively younger individuals. VVAD patients present with visual symptoms in their 50s or 60s and experience a decline in cognitive function typically seen in Alzheimer’s patients.
Non-retinal biomarkers for Alzheimer’s disease include pupillary reactions, such as pupil size and the pupillary response to light. Eye movements also play a crucial role, as Alzheimer’s patients often struggle with reading due to suboptimal eye movements related to memory impairment. These patients show higher latency during voluntary eye movements, decreased eye movement speed, and difficulty fixating or tracking a moving target.
The accessibility and ease of examining the eye make ocular biomarkers attractive for detecting brain illnesses. Retinal imaging is a simple procedure that allows for the examination of visual changes, which can serve as crucial and early indicators of brain pathology.
The recent study conducted at the Duke Eye Center utilized optical coherence tomography angiography (OCTA), a non-invasive technology, to capture high-resolution images of the tiny blood vessels in the retina. The researchers found that people with a healthy brain exhibited a dense network of blood vessels in their retinas, visible during an eye exam. Individuals with an unhealthy brain or Alzheimer’s disease displayed a less pronounced microscopic web of blood vessels.
As ocular biomarkers for Alzheimer’s disease are still in their infancy, they hold great promise in detecting Aβ-related retinal changes specific to the disease’s pathophysiology. The discovery of these ocular markers has the potential to significantly advance our understanding of Alzheimer’s disease.
The development of ocular biomarkers could pave the way for new diagnostic and treatment methods that improve the quality of life for patients with brain diseases. Future research should focus on further advancements in this area, exploring potential avenues for improvement and expanding the use of ocular biomarkers in clinical settings.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
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