Simple eye scan could detect Alzheimer's

Eye tests could be detailed enough to pick up on early signs of Alzheimer's disease, according to scientists.

Researchers say a new type of scan for the eye can show if tiny blood vessels in the back of the eye are changing, and pick up on thinning of the retina.

These could be signs of looming damage in the brain which may lead to Alzheimer's, the most common type of dementia.

And the early test raises hope of patients being treated or making lifestyle changes years before the disease actually develops, potentially adding years to their lives.

The technique called Octa (optical coherence tomography angiography) could revolutionise treatment of the devastating neurological disorder. 

Professor Sharon Fekrat, an ophthalmologist at the Duke Eye Centre in Durham, North Carolina, said: 'If we can detect these blood vessel changes in the retina before any changes in cognition, that would be a game changer.'

Their study of 200 people  

There are drugs which can relieve symptoms of Alzheimer's or slow it down, and they work most effectively in the disease's earliest stages.

Spotting the condition sooner could allow for better treatment, and people could be encourage to change their diet or exercise more to slow down or stop its progress.

The study, published in Ophthalmology Retina, compared the retinas of Alzheimer's patients, people with mild cognitive impairment (MCI) and healthy people.

The Alzheimer's group had lost some of their small retinal blood vessels at the back of the eye. 

A specific layer of their retina – sensitive tissue at the back of the eye – was also thinner. People with cognitive impairment did not show the same changes. 

The accuracy of the test showed it could even distinguish between Alzheimer's and forgetfulness caused by MCI, which can also lead to dementia.

The findings were based on data from more than 350 participants, including 39 with Alzheimer's, 72 with MCI and 254 who were cognitively healthy.

It is the largest analysis of its kind to date and adds to growing evidence Octa is a potentially vital tool in the war on dementia, the leading cause of death in the UK.

The method has assisted much of the recent research on the eye's connection with Alzheimer's.

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

The retina shares many similarities with the brain, the researchers said, suggesting deterioration in one mirrors the other – the two are connected by the optic nerve. 

Professor Fekrat and colleagues said this similarity offers 'a window into the disease process'.

Current dementia medications only treat the symptoms – not the cause – meaning there is still no cure. This has led to an increasing focus on prevention.

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.

Early diagnosis will allow researchers to administer them sooner in the disease process which may lead to better results.

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

They added that this new technique could overcome the hurdle of trying to test millions of people efficiently. 

Current tests are not suitable for widespread screening – brain scans are expensive and spinal taps or lumbar punctures, in which a needle is inserted into the spine to collect cerebrospinal fluid, have risks.

Instead, the disease is often diagnosed through memory tests or observing behavioural changes – by which time the condition has become more advanced.

Professor Fekrat and lead author Professor Dilraj Grewal, who are based in the same lab, expect their work will one day have a positive impact on patients' lives.

Professor Fekrat said: 'Early diagnosis of Alzheimer's disease is a huge unmet need.

'It's not possible for current techniques like a brain scan or lumbar puncture to screen the number of patients with this disease.

'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. Our work is not done.'

She added: 'We need to detect the disease earlier and introduce treatments earlier.'

Her results follow a host of recent studies using Octa that have linked eye changes to Alzheimer's.

The cells of the retina convert light signals coming into the eye into neural signals the brain can interpret.

An earlier study of 32,000 people by University College London using a similar technique found those with thinner retinas were more likely to have problems with memory and reasoning.

Alzheimer's and other forms of dementia affect 850,000 people in the UK - a figure set to rise to 2 million by 2050 because of the ageing population.

Source: The Daily Mail

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