Optical coherence tomography angiography (OCT–A) can detect changes in small blood vessels in the retina which indicate Alzheimer’s. Additionally, it can distinguish between people with Alzheimer’s and those with only mild cognitive impairment. This latest research from researchers at Duke Eye Centre is the largest study to date and adds to current literature as scientists strive to find a quick, non-invasive, inexpensive way to detect Alzheimer’s at the earliest stages.
Because the retina is an extension of the brain and shares many similarities with the brain, researchers believe the deterioration in the retina may mirror the changes going on in the blood vessels in the brain, thereby offering a window into the disease process.
For their study, researchers used OCT-A to compare the retinas in 70 eyes of 39 Alzheimer’s patients, with 72 eyes of 37 people with mild cognitive impairment, and 254 eyes of 133 cognitively healthy people. The Alzheimer’s group had loss of small retinal blood vessels at the back of the eye and a specific layer of the retina was thinner when compared to the mild cognitive impairment and healthy groups. Differences in density were statistically significant after controlling for factors including age and sex.
Diagnosing Alzheimer’s is a challenge. Some techniques can detect signs of the disease but are impractical for screening millions of people – brain scans are expensive and spinal taps have risks. Instead, the disease is often diagnosed through memory tests or observing behavioural changes. The study was published online in Ophthalmology Retina.