In the future, doctors may diagnose Alzheimer’s disease by scanning a patient’s eyes — thanks to new evidence that telltale plaques of amyloid-beta are present not only in the brain, but also in the retina.
Researchers at Cedars-Sinai Medical Center in Los Angeles has developed a method to noninvasively detect amyloid deposits in the eye, potentially allowing for a diagnosis even before symptoms appear. Their report, “Retinal amyloid pathology and proof-of-concept imaging trial in Alzheimer’s disease,” described the results of a small proof-of-concept clinical trial that tested an eye imaging method specifically developed for the study. The work appeared in the journal JCI Insight.
“The findings suggest that the retina may serve as a reliable source for Alzheimer’s disease diagnosis,” Maya Koronyo-Hamaoui, the study’s principal investigator and associate professor at Cedars-Sinai, said in a press release.
Until recently, the only way to positively diagnose Alzheimer’s was by analyzing a patient’s brain after death to detect the diagnostic feature of the disease: aggregates of amyloid-beta in the brain. More recently, researchers started using a brain imaging method called positron emission tomography (PET) to visualize the plaque in living people. But the method requires the use of a radioactive tracer, and is neither cheap nor adapted for repeated use.
In 2011, the team discovered that — just as the eye is considered to be a mirror of the soul — the eye’s retina was a mirror of the brain, at least in terms of amyloid deposits.
In the new study, researchers built on these insights by developing a method to track changes by eye imaging. They did so with curcumin, the main component of the spice turmeric. Curcumin, which study participants drank, entered the amyloid plaque and lit up in the eye scan.
“One of the major advantages of analyzing the retina is the repeatability, which allows us to monitor patients and potentially the progression of their disease,” said Koronyo-Hamaoui.
In the study process, the research team discovered that amyloid deposits were also present in peripheral areas of the retina, which they had previously overlooked. Moreover, the amount of amyloid plaque in the retina correlated with the amyloid burden in specific brain regions.
“Now we know exactly where to look to find the signs of Alzheimer’s disease as early as possible,” said research associate Yosef Koronyo, first author on the study.
Added Dr. Keith L. Black, chair of Cedars-Sinai’s Department of Neurosurgery and director of the Maxine Dunitz Neurosurgical Institute: “Our hope is that eventually the investigational eye scan will be used as a screening device to detect the disease early enough to intervene and change the course of the disorder with medications and lifestyle changes.”