Can the Eyes Have It? Can Eye Scans Predict Alzheimer's?

Here is some news hot off the press! This news was just released a few days ago.

Being a retired ophthalmologist, I find these findings are unusually interesting and dear to my heart. More importantly, they are phenomenally earth shattering if the results are independently confirmed in the future.

Two papers were presented at the 2018 meeting of the American Academy of Ophthalmology that may make the prediction of future Alzheimer's (AD) onset and progression earlier and less costly with relatively non-invasive eye tests.

1 - Retinal Thickness Study

The first study, as reported by Ygal Rotenstreich, MD, e.t al. of the Goldschleger Eye Institute at Sheba Medical Center, Tel Aviv, Israel. involved measuring the thickness of the retina (inner lining of the eye).

The study showed that people with a family history of Alzheimer's had thinner inner layers of their retinas and corresponding thinning of the hippocampus, which was separately measured by a brain scan. Of particular note is that none of the patients studied had any symptoms of AD or MCI.

The hippocampus is the part of the brain greatly responsible for memory and is invariably thinned as AD progresses.

Rotenstreich stated that “Inner retinal layer thickness is associated with cognitive function and hippocampal volume and may present a novel bio-marker for very early detection of Alzheimer's  disease.”

The implication of this study means that AD can possibly be diagnosed much earlier than any study currently available.


2 - Retinal Blood Vessels Study 

This study, led by Sharon Fekrat, MD, and Dilraj Singh Grewal, MD, both of Duke University in Durham, NC, consisted of multiple eye studies of patients over 50 years old from the Duke Memory Disorders Clinic with AD or MCI as well as community-based healthy volunteers without known memory problems. In short, it was found that blood vessels in the eye may be a predictor of the progression of AD.

Findings concluded that patients with AD had significantly reduced retinal small vessel density and perfusion density (flow characteristics) compared to patients with mild cognitive impairment (MCI) and the normal volunteers. Perfusion density was also lower in MCI patients compared to the normals.

The retinal microvasculature (very small blood vessels) was measured by optical coherence tomography angiography, which is a relatively non-invasive procedure compared to current diagnostic tools such as spinal taps or not readily available and expensive PET scans.

It was concluded that changes in the retinal micro-vasculature may mirror small-vessel cerebrovascular (brain) changes in Alzheimer disease. The findings suggest a continuum of decreasing retinal blood flow starting with normals, then progressing to MCI and eventually AD. These findings could make the progression of AD detectable earlier in the course of its illness.


Conclusion.

It is not really surprising that both studies were of the retina. Any eye doctor could tell you that the retina is considered an extension of the brain. Both studies offer hope that AD may be detected or measured at very early stages with relatively simple non-invasive tests. More conclusive testing is warranted for both studies.