Alzheimer’s disease progression can be detected through the retina
It is often said that the eyes are the windows to the soul. However, current research indicates that the eyes might also serve as windows for health issues.
According to an NIA-funded study, several changes in the brain that occur during Alzheimer’s disease can appear in the retina – a layer of tissue located at the back of the eye that contains specialized cells called photoreceptors, which are responsible for capturing light and initiating the visual process.
The retina can be affected by a variety of eye illnesses and diseases, including retinal detachment, macular degeneration, and diabetic retinopathy. Regular eye exams and early medical intervention are critical for maintaining retinal health and keeping healthy vision.
The findings, published in Acta Neuropathologica, provide information on the effects of Alzheimer’s disease on the retina and imply that noninvasive methods of retina monitoring could be used to consistently detect and track the condition.
Previous research has discovered symptoms of Alzheimer’s disease in the retina, such as amyloid protein accumulation and tissue thinning. Researchers at Cedars-Sinai Medical Center in Los Angeles examined donated postmortem retina and brain tissue from 86 people to better understand how these alterations in the retina connect to the evolution of Alzheimer’s.
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The researchers discovered that amyloid deposits in the retina were five times greater in people with mild cognitive impairment (MCI) and nine times higher in patients with Alzheimer’s disease as compared to cognitively unimpaired people. The deposits were also unevenly distributed across the retina in all cases. The majority were discovered in the inner layers and parts of the retina involved in peripheral vision.
People with Alzheimer’s had larger amounts of amyloid plaques in their retinas than those with MCI. Furthermore, the researchers discovered that retinal abnormalities were associated with the severity of brain changes. These findings imply that amyloid deposits in the retina increase with Alzheimer’s disease progression and could be utilized to diagnose the condition early.
According to the Alzheimer’s Association, Alzheimer’s disease is caused by a combination of factors, including age, genetics, lifestyle, and environment. Other risk factors include traumatic brain injury, as well as heart and brain health. Conditions that harm the heart and blood arteries, such as heart disease, diabetes, stroke, high blood pressure, and high cholesterol, appear to increase the chance of developing vascular dementia.
The researchers then examined the retina tissue for the presence of microglia and other nervous system immune cells. Microglia aid in the removal of cellular waste such as amyloid plaques. The researchers discovered an increase in the number of microglia in MCI and Alzheimer’s retinas, but the fraction of these active in clearing away amyloid plaques was lower than in cognitively unimpaired brain samples. This shows that these retinal microglia may not be operating properly, as occurs in Alzheimer’s patients’ brains, and may contribute to the formation of amyloid deposits over time.
The researchers analyzed the proteins present in the retinas and brain tissue of donors with Alzheimer’s to those with normal cognition to assess the effects of Alzheimer’s on cellular processes in the retina. They discovered that in the brains and retinas of Alzheimer’s patients, proteins implicated in inflammation and neurodegeneration were activated, whereas those involved in cellular energy production and light perception were suppressed. These findings suggest that the retina may “mirror” the brain alterations linked with Alzheimer’s disease.
Sources: National Institute on Aging
Alzheimer’s Association
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