Retinal Imaging to Detect Alzheimer's Disease Risk

Article: Eyes Provide Peek at Alzheimer’s Disease Risk
Source: University of California, San Diego, Medicine
Published: August 23, 2021

Amyloid deposits tagged by curcumin fluorescence in a retinal scan

The vasculature of the retina and its exposure as an extension of the brain allow the eyes to be an excellent organ for monitoring of neurological and systemic diseases. The ability to visibly access the retina via noninvasive imaging techniques opens a valuable window for evaluation of neurological pathologies by retinal fundus imaging, especially as an early biomarker to assess disease risk. Researchers at UC San Diego conducted a cross-sectional pilot study investigating the feasibility of detecting amyloid plaques, a hallmark of Alzheimer's disease, in the retina in the context of clinical trials. Specifically, they analyzed the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) trial, a nationwide clinical trial exploring ways to reduce or prevent the formation of beta-amyloid deposits in neural tissue. The researchers compared retinal and cerebral amyloid in clinically normal individuals who screened positive for high amyloid levels through positron emission tomography (PET). Additionally, the researchers looked at the Longitudinal Evaluation of Amyloid Risk and Neurodegeneration (LEARN) study, which comprises a cohort of individuals who exhibited low levels of amyloid on PET. The authors report, "The four participants from the A4 trial showed a greater number of retinal spots compared to the four participants from the LEARN study. We observed a positive correlation between retinal spots and brain amyloid, as measured by the standardized uptake value ratio (SUVr)." The researchers acknowledge the limitations of the small pilot dataset of only eights patients, adding that "these findings are encouraging because they suggest it may be possible to determine the onset, spread and morphology of AD—a preclinical diagnosis—using retinal imaging, rather than more difficult and costly brain scans." They look forward to larger studies, both cross-sectionally and longitudinally.

My rating of this study: ⭐⭐

Ngolab J, Donohue M, Belsha A, et al. "Feasibility study for detection of retinal amyloid in clinical trials: The Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) trial." Alzheimer's & Dementia.  17 August 2021. https://doi.org/10.1002/dad2.12199