Detecting Early Alzheimer Disease With Noninvasive Imaging Device

November 28, 2018

Currently, detecting Alzheimer disease (AD) is a challenge. However, a new, noninvasive imaging device—which examines the smallest veins in the back of the eye, including the red blood cells moving through the retina—can be used to detect signs of AD, researchers said.

The precise and non-invasive imaging device is known as optical coherence tomography angiography (OCTA). The device enables physicians to observe small blood vessels in the retina at the back of the eye, which may be altered in patients with AD.

Although some current techniques can detect signs of AD, they are often impractical for screening millions of patients. Notably, brain scans are expensive and spinal taps can be harmful. Oftentimes physicians tend to perform memory tests in order to diagnose a patient, and by the time these changes are noticed, the disease is in advanced stages. 

Despite the lack of a cure for AD, early diagnosis is critical. In order to find a quick and inexpensive way to detect the disease in its earliest stages, researchers from Duke University used OCTA to compare the retinas of patients with AD to those of people with mild cognitive impairment, as well as those of healthy people. 

The researchers, led by Sharon Fekrat, MD, professor of ophthalmology at Duke, and colleagues, found that the AD group had loss of small retinal blood vessels at the back of the eye and that a specific layer of the retina was thinner. Dr Fekrat and colleagues noted that even patients with mild cognitive impairment did not show this change. 

“This project meets a huge unmet need,” Dr Fekrat said. “It’s not possible for current techniques like a brain scan or lumbar puncture (spinal tap) to screen the number of patients with this disease. Almost everyone has a family member or extended family affected by [AD]. We need to detect the disease earlier and introduce treatments earlier.”

In a separate study, a team of researchers from Sheba Medical Center in Israel examined 400 patients who had a family history of the disease but were showing no signs themselves. The researchers noted that genes play a significant role in how AD begins and progresses.  

According to the findings of the second study, the researchers found that patients with a family history of AD had a thinner inner layer of the retina. Further, a brain scan showed that their hippocampus, an area of the brain that’s first affected by the disease, had already begun to shrink. The researchers said that a thinner inner retina layer and smaller hippocampus often lead to scoring worse on a cognitive function test.

“A brain scan can detect [AD] when the disease is well beyond a treatable phase,” said lead researcher Ygal Rotenstreich, MD, an ophthalmologist at the Goldschleger Eye Institute at Sheba Medical Center. “We need treatment intervention sooner. These patients are at such high-risk.”

These findings were presented at the Annual Meeting of the American Academy of Ophthalmology.

Julie Gould