If we can detect these blood vessel changes in the retina before any changes in cognition, that would be a game changer'.
For their study, researchers used OCTA to compare the retinas of 39 Alzheimer's patients with 37 people with mild cognitive impairment, and 133 cognitively healthy people. They found that the density of blood vessels was less, and thickness of one particular layer of the retina was thinner among people with a known diagnosis of Alzheimer's, compared to the other groups.
In the US alone, 5.8 million people are living with Alzheimer's dementia, according to 2019 data from the Alzheimer's Association. It is rarer in younger people, although they can be affected by Alzheimer's too.
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. Past research has sought a way to diagnose the disease at an earlier stage, potentially making it possible to start treatment or make lifestyle changes to help mitigate the progression.
Alzheimer's remains an incurable, fatal disease suffered by millions of people from around the world, and can only be treated by palliative means.More news: Full house star Lori Loughlin arrested for bribery
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"We know that there are changes that occur in the brain in the small blood vessels in people with Alzheimer's disease, and because the retina is an extension of the brain, we wanted to investigate whether these changes could be detected in the retina using a new technology that is less invasive and easy to obtain", said Dilraj S. Grewal, M.D., a Duke ophthalmologist and retinal surgeon and a lead author on the study.
So why may there be poor blood supply to the eyes of people with Alzheimer's?
They stressed that while they have proved that blood vessels become sparser in those with Alzheimer's, the next step is to show this happens before memory problems appear, which would give doctors a way to diagnose the condition years in advance. It may get trapped in the deposits of another protein called amyloid that is commonly associated with in the disease.
New studies could be conducted with patients with mild cognitive impairment but higher amyloid concentrations. Results could be helpful in the fight against Alzheimer's disease.
Dr Fekrat said: 'Our work is not done.