Simple eye tests could be used to spot Alzheimer’s disease years before patients begin to lose their memory, a study suggests.
Eye specialists have shown elderly people with Alzheimer’s have fewer of the microscopic blood vessels that usually form a web at the back of the eye.
The breakthrough raises the prospect that opticians could look for signs of dementia during annual eye checks.
Currently the only ways to definitively diagnose Alzheimer’s are through expensive brain scans or by taking a fluid sample from the patient’s spinal cord.
Doctors are desperate to come up with a way to spot the disease much earlier when lifestyle changes could minimise the extent of the damage. More than 500,000 people in Britain suffer from Alzheimer’s and the total is rising, but most are diagnosed too late to do anything about it.
Scientists from Duke University in the US found the eye seems to reflect changes taking place deep within the brain.
Their study of 200 people, published in the journal Ophthalmology Retina, showed that those with Alzheimer’s had a less dense coating of blood vessels at the back of the eye, with gaps appearing in places. The scientists believe the same thing is happening in the brain, with blood vessels disappearing as Alzheimer’s take hold.
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.
Dr Sharon Fekrat, of Duke University Medical Centre, said the scans take only a few minutes using an technique known as optical coherence tomography angiography (Octa), which allows doctors to see retinal blood vessels smaller than the width of a human hair.
The scanners are already used by many ophthalmologists and could easily be built into a standard eye examination.
For the study, scientists used Octa to compare the retinas of 39 Alzheimer’s patients, 37 people with mild cognitive impairment, and 133 healthy individuals with normally functioning brains.
They found the blood vessel network was less dense in the Alzheimer’s patients compared with the other groups. In addition, a specific layer of the retina was thinner in those with Alzheimer’s.
Dr Fekrat said: ‘Our work is not done. If we can detect these blood vessel changes in the retina before any changes in cognition, that would be a game changer.’