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Retinal imaging detects biomarker for Alzheimer’s: Novel yes, but practical?

Clinical study shows that retinal imaging may detect signs of Alzheimer's disease

Our Review Summary

Claims are made all the time in news releases without a lot of clarity on how novel the findings of a study really are. This release clearly articulates the new elements being reported — retinal imaging in this case — in detection of Alzheimer’s. It also does a nice job explaining not only how the work was funded but also who supplied the material to do the experiments. What’s missing are important explanations about costs — especially given that cost comparison is a central selling point for this diagnostic tool in the release — and details about risks, details about benefits, and a fuller explanation of clinical applicability now versus in the future.



Why This Matters

The release describes an early study of scans of the retina that identify the hallmark sign of Alzheimer’s disease brains in living patients. The hope is that patients with disease can be identified early and their disease progression followed as treatments are tested. The retina is an outgrowth of the brain, so it makes sense that it would also contain the hallmark amyloid plaques found in the brains in large amounts in people with Alzheimers. A non-invasive scan like this would be advantageous over more invasive tests such as positron emission tomography (PET) scans and spinal taps.

There’s a popular idea that identifying people with Alzheimer’s pathology early would allow early and more successful treatment, although there is as yet no treatment available. In addition, most dementias are a mix of Alzheimer’s pathology (amyloid plaques, neurofibrillary tangles, and nerve cell loss), blood vessel disease, and other degenerative changes that occur with age, so thinking that identifying amyloid plaques early, as described in this release, is going to do any good has become increasingly controversial as trial after trial of drugs targeting amyloid have failed. Regardless, a goal of many researchers and companies is to find biomarkers to identify people early and also to follow disease progress with treatment, preferably with tests that are noninvasive and inexpensive.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

High up in the release it says:

“Accumulations of neurotoxic beta-amyloid protein can be detected with positron emission tomography, or PET scans, and analysis of cerebrospinal fluid, but these are invasive, inconvenient and costly, making them impractical for routine screening and follow-up evaluation.”

We love this kind of comparison but we expect those comparisons to be backed up. What makes these other diagnostic tools “invasive, inconvenient, and costly”? How much do they cost? How much does this type of diagnostic cost? Remember, the study was done on deceased people’s brains and retinas. So you can’t get much more invasive than that.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

In a news release of more than 1,000 words, we would expect some data to back things up. Instead, this release offers just two numbers by way of quantification, and both of them are couched in relative terms that, to any reader other than the authors of the study, may be meaningless. The release says:

“Among key findings, the researchers report a 4.7-fold increase in retinal plaque burden in patients with Alzheimer’s, compared to controls, and they provide observations regarding geometric distribution and layer location of amyloid pathology in the retina. … The demonstration of a fully automated calculation quantifying retinal autofluorescence that showed a 2.1-fold increase in patients with Alzheimer’s, compared with controls.”

In a study that compared the brains of 23 deceased people with Alzheimer’s to 13 people without, what do these numbers mean?

Because the research is very preliminary, and given there is no treatment for Alzheimer’s pathology and most people with dementia who are in their 80s have multiple cognitive issues, it’s difficult to see how identifying amyloid — or even multiple types of pathology — is going to benefit patients.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

There is a reference to how other ways of detecting Alzheimer’s are “invasive” but there is nothing in the release about the possible harms associated with this diagnostic tool. A false-positive diagnosis of dementia or Alzheimer’s would be one such harm.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The release explains how the study was conducted with a good amount of detail. We would have liked to have seen a better explanation, though, of how this type of lab study on dead tissue has been extrapolated to indicate any sort of findings — positive or negative — about a diagnostic tool for living patients.

To fully understand the presence of retinal plaque researchers would also need to test people with other diseases that are also known to have amyloid, such as Parkinson’s and Lewy body dementia, and also people with various eye disease such as glaucoma, which might change the results. The release states researchers also did a feasibility trial in 16 patients to test the ability to identify beta-amyloid in the eye using autofluorescence imaging, but we’re given none of the results from this part of the study.

Does the news release commit disease-mongering?


There is no disease mongering in the release.

Does the news release identify funding sources & disclose conflicts of interest?


Everyone quoted in the release is affiliated with the company that makes the diagnostic tool that is being tested, and that is made clear. The funding sources are also made very clear. And we were also happy to see this level of detail about the study:

Clinical trials were approved by Quorum Review, Seattle, Washington, (IRB00003226) and the U.S. Department of Health and Human Services (FWA00019841). Human tissues were obtained from the USC Alzheimer’s Disease Research Center (ADRC) Neuropathology Core, Los Angeles, CA (IRB protocol: HS-042071).

Animal studies were approved by the Cedars-Sinai Medical Center Institutional Animal Care and Use Committee (IACUC) and the Division on Laboratory Animal Medicine (DLAM) at UCLA.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

As noted, there is a passing reference to other types of diagnostic tools but no true comparisons.

Does the news release establish the availability of the treatment/test/product/procedure?


Although not as clearly stated as it could be, it does come across in one of the quotes that this is a technology that is not yet available for use.

“It’s exciting to see these studies demonstrating the power of the technology applied to the Alzheimer’s field. Our goal is to develop a product that is easy to use, affordable and widely accessible. We look forward to the potential of retinal imaging playing a vital role in solving the problem of Alzheimer’s, both in identifying and monitoring those who may be affected by the disease. Our next step is to continue with clinical trials, building upon the existing pharmaceutical company collaborations, to ensure our technology is ready for the medical community to help manage this disease.”

Does the news release establish the true novelty of the approach?


The release establishes the novelty of the findings in several areas, noting:

The article provides new insights into the disease’s manifestations in the retina and information on the optical imaging system. Here are several highlights:

  • The first histologic quantitative analysis of retinal plaque clusters, or “hot spots,” containing the most toxic forms of beta-amyloid with specific distribution patterns in superior peripheral regions that were previously unexplored.
  • A detailed analysis of beta-amyloid deposit types using electron microscopy.
  • The first report of certain Alzheimer’s-related pathologies in the retina, including vascular amyloid pathology.
  • The demonstration of a significant correlation between retinal and brain plaques, and coexistence of neuronal loss.
  • The first feasibility study for noninvasively detecting presumed amyloid deposits in retinas of living patients.
  • The demonstration of a fully automated calculation quantifying retinal autofluorescence that showed a 2.1-fold increase in patients with Alzheimer’s, compared with controls.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


We did not see any unjustifiable language in the release.

Total Score: 5 of 10 Satisfactory


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