Can Changes in the Eye Help Identify Alzheimer’s?

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The weblike microscopic network of blood vessels in the macular area of the retina is much less dense in individuals with Alzheimer’s disease (AD) than in those without it, according to a 2019 study in Ophthalmology Retina. This finding could represent an accessible, noninvasive way to screen for AD.

Researchers used a new scanning technology called optical coherence tomography angiography (OCTA)—a noninvasive imaging technique that measures blood flow in each layer of the retina. They analyzed 39 individuals with AD, 37 with mild cognitive impairment (MCI), and 133 healthy controls—a total of 396 eyes. Participants in the study were age 50 or older.

AD participants showed significantly reduced microvascular structure in several macular areas compared with MCI participants and controls. A comparison of measurements in those with MCI and in control participants, however, revealed no significant differences between the two groups in microvascular structure in most macular areas.

Does this mean that one day physicians will be able to detect AD using a simple eye exam? It’s too soon to tell, but investigators have been searching for such a technique. Current imaging technologies cannot reveal the microvascular changes in the brain that characterize AD, and it may well be that the retinal changes that investigators observed mirror those in the brains of individuals with AD.