A non-invasive examination of the eye may be enough to identify Alzheimer’s early! Now, that’s what I call good news!

A new imaging technique, to visualise the retina, in fact, could help to recognise the disease and distinguish people who have mild cognitive impairment instead, a phase that may precede Alzheimer’s and other forms of dementia. To achieve this result is a research group coordinated by Duke University’s Duke Eye Center. This new opportunity for investigation comes from the fact that the loss of blood vessels in the retina could be a spy of Alzheimer’s disease. The results are published on Ophtalmology Retina, magazine of the American Academy of Ophtalmology.

blue-eyes-close-up-eyeThe technique in question is called angiography based on optical coherence tomography (the abbreviation is Octa), which allows to study in vivo and in a non-invasive manner – the cellular layers of the inside of the eye, in particular the nerve fibers of the retina.

The retina is a nervous tissue that, together with other structures, connects the eyeball to the brain and is therefore compared by the authors to an extension of the brain. For this reason the researchers believe that a deterioration of the blood vessels of the retina is a signal of presence of the same damage also in the brain, a signal of Alzheimer’s disease.

A third control group consists of 133 people without any of these disorders. 

39 patients with Alzheimer’s were considered, 37 patients with mild cognitive impairment, a slight cognitive decline, which includes a worsening of some abilities such as memory and reasoning ability and which increases the risk of Alzheimer’s.
 
According to the results of their research, the group with Alzheimer’s has a loss of the small vessels of the retina, much thinner vessels than a hair, which instead is absent in the group with slight cognitive decline. Furthermore, a specific cellular layer of the retina was found to be of lower density in patients with Alzheimer’s disease. The following image shows the differences, where the highest concentration of blood vessels is indicated with orange and red and is present in people who had only a slight cognitive decline.
 
retina alzheimer

On the left, a person’s retina with mild cognitive impairment shows a network of blood vessels in the denser retina.

Alzheimer’s is a progressive neuro-degenerative disease, for which there are currently no cure but treatments to slow the progression of the disease. For this reason, early diagnosis plays an essential role in identifying the disease promptly and curbing its progress for as long as possible. The diagnosis, at present, is based on symptoms and clinical history, physical and neurological examination, clinical examinations (including analysis of spinal fluid through lumbar puncture) and cerebral MRI.

However, early diagnosis is not always possible for all millions of patients with these traditional tools. “The early diagnosis of Alzheimer’s is a broad unmet need,” explains Sharon Fekrat, professor of ophthalmology at Duke University, “with current techniques such as brain imaging or lumbar puncture, it is not possible to assess the large number of patients with this disease”. In this setting, studying blood vessel reduction could provide a new tool for diagnosis. “Our work is not finished”, continues Fekrat, “If we can detect these changes in the blood vessels in the retina before any other change in cognitive abilities, this result would represent an element of revolution.”

“Finally the goal could be to use this tool to detect Alzheimer’s early, before the symptoms of memory loss are evident and to be able to monitor these changes over time in the people taking part in clinical trials to study new treatments for Alzheimer’s disease”.