The simple and inexpensive eye test could be part of routine examinations by high street opticians in as little as three years, allowing those in middle age to be screened.
Dementia experts said it had the power to revolutionise the treatment of Alzheimer’s by making it possible for drugs to be given in the earliest stages.
Simple: The middle-aged could visit their local optician and have the special eye test as part of a routine examination
The technique, being pioneered at University College London, could also speed up the development of medication capable of stopping the disease in its tracks, preventing people from ever showing symptoms.
Rebecca Wood, of the Alzheimer’s Trust, said: ‘These findings have the potential to transform the way we diagnose Alzheimer’s, greatly enhancing efforts to develop new treatments.’
Alzheimer’s and other forms of dementia blight the lives of 700,000 Britons and their families, and the number of cases is expected to double within a generation.
There is no cure and existing drugs do not work for everyone.
Current diagnosis is based on memory tests, and expensive brain scans are also sometimes used.
However decisive proof of the disease usually comes from examination of the patient’s brain after death.
Diagnosis: Eye drops would be used in the test to highlight diseased cells at the back of the eye
The eye test would provide a quick, easy, cheap and highly-accurate diagnosis.
It exploits the fact that the light-sensitive cells in the retina at the back of the eye are a direct extension of the brain.
Using eye drops which highlight diseased cells, the UCL researchers showed for the first time in a living eye that the amount of damage to cells in the retina directly corresponds with brain cell death.
They have also pinpointed the pattern of retinal cell death characteristic of Alzheimer’s. So far their diagnosis has been right every time.
With research showing that cells start to die ten to 20 years before the symptoms of Alzheimer’s become evident, it could allow people to be screened in middle age for signs of the disease.
However, some may not want to know their fate so far in advance. There is also the fear that insurance companies could increase premiums for those who test positive while still young.
The experiments, reported in the journal Cell Death & Disease, have been on animals but the team are poised to start the first human trials.
Researcher Professor Francesca Cordeiro said: ‘The equipment used for this research is essentially the same as is used in clinics and hospitals worldwide.
‘It is also inexpensive and non-invasive, which makes us fairly confident that we can progress quickly to its use in patients.
‘It is entirely possible that in the future a visit to a high street optician to check on your eyesight will also be a check on the state of your brain.’
The technique could also improve the diagnosis of other conditions, including glaucoma and Parkinson’s disease.
In the short term, an early diagnosis would give patients and their families much more time to prepare for the future.
In the longer term, it would allow new drugs that stop the disease in their tracks to reach their full potential.
Professor Cordeiro said: ‘If you give the treatment early enough, you can stop the disease progressing, full stop.’
Dr Susanne Sorensen, of the Alzheimer’s Society, cautioned that the test was still experimental but added: ‘This research is very exciting. If we can delay the onset of dementia by five years, we can halve the number of people who will die from the disease.’