An eye exam could one day provide early diagnosis of Alzheimer's

Breakthrough Microscopic blood vessels at the back of the eye could pre-determine the early onset of Alzheimer's

Dr Rosa Sancho from Alzheimer's Research UK said: "We know that diseases like Alzheimer's begin in the brain decades before symptoms like memory loss start". They compared the density and thickness of these blood vessels in 133 healthy individuals, 37 people with mild cognitive impairment (sometimes a precursor to Alzheimer's disease) and 39 people with Alzheimer's disease. Not only were the researchers able to detect differences between the Alzheimer's patients and the other two groups, but they were also able to see differences among the Alzheimer's patients that appeared to be linked with the severity of the disease.

The new study's authors propose reduced blood flow to the eyes may be because the protein that signals blood vessels to grow and proliferate is found at low levels in people with Alzheimer's. "We also found a reduction in the thickness of (of a specific layer of the retina) in Alzheimer's patients compared to controls and those with mild cognitive impairment".

It enables physicians to see blood vessels in the back of the eye that are smaller than the width of a human hair.

The findings are published in the journal Ophthalmology Regina.

A new kind of precise and non-invasive imaging called optical coherence tomography angiography (OCTA) has assisted much of the recent research on the eye's connection with Alzheimer's. "It will be many years before it goes into prime time", Dr. Fekrat said.

Alzheimer's remains an incurable, fatal disease suffered by millions of people from around the world, and can only be treated by palliative means.

One of the main reasons new drugs have been ineffective so far is they are administered too late to trial patients - when the disease is advanced.

It would also give patients time to plan for the future with their families - while they still have their faculties, said the United States team.

Prof Fekrat said: "Early diagnosis of Alzheimer's disease is a huge unmet need". But such techniques to study the brain are invasive and costly.

"It's possible these changes in blood vessel density in the retina may mirror what's going on in the tiny blood vessels in the brain".

Now diagnosing Alzheimer's is tricky, requiring an expensive brain scan, a risky spinal tap or in most cases a behavioural assessment by a doctor based on symptoms.

In the USA alone, 5.8 million people are living with Alzheimer's dementia, according to 2019 data from the Alzheimer's Association.

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