A HEALTH test available on the high street could spot signs of Alzheimer’s well before symptoms appear, scientists say.
When’s the last time you got your eyes checked?
US researchers said the routine test may be able to spot changes to tiny blood vessels in the retinas.
They linked this change to a common genetic mutation that can increase the risk of Alzheimer’s , in a study published to Alzheimer’s & Dementia .
Spotting it early could help spot the memory-robbing condition early, lead author Alaina Reagan suggested.
The neuroscientist at The Jackson Laboratory (JAX), a research institute based in Maine, said: “If you’re at an optometrist or ophthalmologist appointment, and they can see odd vascular changes in your retina, that could potentially represent something that is also happening in your brain, which could be very informative for early diagnostics.”
The retina is a layer of cells at the back of your eyeball that converts light into nerve signals and sends them to your brain.
Scientists often see the retina as an extension of the brain that shares essentially the same tissue.
That’s why changes in retinal blood vessels can offer early clues about brain health and diseases like Alzheimer’s, Dr Reagan said.
“Your retina is essentially your brain, but it’s much more accessible because your pupil is just a hole, and we can see tons of stuff,” she explained.
“All the cells are very similar, all the neurons are quite similar, all the immune cells are quite similar, and they behave similarly under pressure if you’ve got a disease.”
The team studied mice with a mutation called MTHFR677C>T, which up to 40 per cent of people have.
The mice had twisted blood vessels in their retinas, narrowed and swollen arteries, and less vessel branching than rodents without the mutation, from as young as six months.
This is similar to changes in the brain that are linked to poor blood flow and increased risk of cognitive decline, according to researchers.
Vessels that appear more twisted and looped than normal can signal problems with high blood pressure, as the narrowing tissue limits the flow of nutrients and oxygen, Dr Reagan said.
“We can see these wavy vessels in the retinas, which can occur in people with dementia ,” she went on.
“That speaks to a more systemic problem, not just a brain- or retina-specific problem.
“It could be a blood pressure problem affecting everything.”
A 2022 study by Dr Reagan and Gareth Howell, professor and Diana Davis Spencer Foundation Chair for Glaucoma Research at JAX, found similar changes to the blood vessels in the brains of mice with the MTHFR677C>T mutation.
“These mice have fewer vessels in their cortex and reduced blood flow to their brains,” Dr Reagan said.
Early signs of dementia
It's not unusual for your memory to lapse a bit as you get older.
But dementia is different from ‘just getting old’ as it will cause noticeable – rather than gradual – changes to mental abilities and make managing everyday tasks and activities increasingly difficult.
The symptoms of dementia may be small to start with, but get worse over time.
Below are some examples of possible signs.
Memory loss
Memory loss is a key sign of dementia. This can include:
- Forgetting something you were only recently told. You may ask for the same information repeatedly – for example, ‘Are the doors locked?’
- Putting objects in unusual places – for example, putting your house keys in the refrigerator.
- Being unable to learn new tasks, like how to use a new washing machine.
Planning and decision making issues
People with dementia can have difficulty with planning and decision making. This can include:
- Getting very confused when planning or thinking things through.
- Struggling to stay focused on a single task.
- Not making informed, careful decisions when dealing with money or looking at risks.
- Finding it hard to manage regular payments, budgets or monthly bills.
Problems with language and understanding
In people with dementia, this can manifest as:
- Having frequent problems finding the right word or regularly referring to objects as ‘that thing’.
- Finding it hard to take part in conversations.
- Regularly being unable to follow what someone is saying even without distractions.
Losing sense of time and place
Dementia can cause problems with orientation, including:
- Losing track of the date, season or the passage of time.
- Getting lost in a place that is familiar or that should be easy to find your way around – for example, a supermarket.
- Regularly being unable to follow what someone is saying even without distractions.
Problems with vision and perception
This can mean having problems making sense of what you see.
For example, having difficulty judging distances on stairs, or mistaking reflections or patterns for other objects.
Mood and behavioural changes
Finally, dementia can also make people act differently or shift their mood. This can mean:
- Becoming withdrawn and losing interest in work, friends or hobbies.
- Feeling unusually sad, anxious, frightened or low in confidence.
- Getting easily upset at home, at work, with friends or in places that usually feel comfortable or familiar.
Source: Alzheimer’s Society
The results add weight to the theory that blood vessel health plays a major role in the development neurodegenerative diseases like Alzheimer’s and other forms of dementia, according to the neuroscientist.
“A lot of these molecular changes are happening in conjunction, which suggests these systems in brain and retinal tissue are working in tandem,” she said.
Further research is needed to prove the link between twisted blood vessels in the retina and Alzheimer’s, the study team noted.
They plan to further investigation whether vascular changes can be linked to the MTHFR677C>T mutation in humans, as well as whether the new insight could be used in eye exams, in partnership with clinicians and dementia care specialists at Northern Light Acadia Hospital in Bangor, Maine.
The aim is to learn more about how eye health adds to overall risk for dementia, so that clinicians can know what signs to look for in patients.
Dr Reagan said: “Most people over 50 have some kind of vision impairment and get checked annually for prescription changes.
“Are they more at risk if they have these vascular changes, and is that a point when doctors could start mitigating brain changes?
“That could be 20 years before cognitive damage becomes noticeable to patients and their families.”
Previous studies have explored the link between eye health and dementia .
Researchers at Johns Hopkins University in the US estimated that vision problems play a role in up to one in five dementia cases .
Meanwhile, blood tests have become a big focus in dementia diagnosis.
