EWJ June 2024 web - Journal - Page 37
How Your Vision Can Predict Dementia
12 Years Before it is Diagnosed - New Study
The eyes can reveal a lot about the health of our brain. Indeed, problems with the eyes can
be one of the earliest signs of cognitive decline. Our latest study shows that a loss of visual
sensitivity can predict dementia 12 years before it is diagnosed
Our research was based on 8,623 healthy people in
Norfolk, England, who were followed up for many
years. By the end of the study, 537 participants had
developed dementia, so we could see what factors
might have preceded this diagnosis.
when they meet them. People with dementia can
sometimes seem lost, because they do not purposefully move their eyes to scan the environment, including that of the face of the people they have just
met.
At the start of the study, we asked participants to take
a visual sensitivity test. For the test, they had to press
a button as soon as they saw a triangle forming in a
field of moving dots. People who would develop dementia were much slower to see this triangle on the
screen than people who would remain without
dementia.
It would follow that you would then later be less able
to recognise people as you have not imprinted their
features. So this early issue in not recognising people
you have just met could be related to ineffective eye
movement for new faces, rather than being a pure
memory disorder.
Can eye movement improve memory?
However, as visual sensitivity is related to memory
performance (even using non-visual tests), we are also
testing whether getting people to do more eye movements helps to improve memory. Previous research
on the matter is mixed, but some studies found that
eye movement can improve memory. Perhaps that explains why we found that people who watch more
TV and read more have better memory and less
dementia risk than those who do not.
So why might that be?
Visual issues may be an early indicator of cognitive
decline as the toxic amyloid plaques associated with
Alzheimer’s disease may first affect areas of the brain
associated with vision, with parts of the brain associated with memory becoming damaged as the disease
progresses. So vision tests may find deficits before
memory tests do.
There are several other aspects of visual processing
that are affected in Alzheimer’s disease, such as the
ability to see outlines of objects (contrast sensitivity)
and to discern between certain colours (the ability to
see the blue-green spectrum is affected early in dementia), and these can affect people’s lives without
them being immediately aware it.
Dr Anke Hensiek
Dr med, PhD, FRCP
Affiliated Assistant Professor University of Cambridge
Another early sign of Alzheimer’s is a deficit in the
“inhibitory control” of eye movements, where distracting stimuli seem to hold attention more readily.
People with Alzheimer’s seem to have an issue ignoring distracting stimuli, which may show up as eyemovement-control issues.
Consultant Neurologist
Dr Hensiek is an experienced Consultant Neurologist at
Addenbrookes Hospital, Cambridge.
She has extensive experience in all aspects of neurology,
including headache, pain, head-injury, epilepsy, Parkinson's
Disease, neuropathy, muscle disorders, memory problems,
If dementia makes it harder to avoid distracting
stimuli, then these problems could increase the risk
of driving accidents – something we are currently
investigating at Loughborough University.
movement disorders and Multiple Sclerosis.
She conducts specialist clinics in motor neuron disease and
hereditary neurological conditions including ataxia, spastic
paraparesis and neurofibromatosis. She has a strong academic
Recognising faces
We have some evidence which suggests that people
with dementia tend to process new people’s faces inefficiently. In other words, they don’t follow the usual
pattern of scanning the face of the person they are
talking to.
background with ongoing clinical research involvement.
In healthy people, this would be from eyes to nose to
mouth. We do this to “imprint” the face and remember it for later. People can sometimes sense when the
person they are talking to does not do this.
Email: kayleigh.shough@nhs.net
In fact, some doctors working with people with
dementia will recognise that someone has dementia
Nationwide
EXPERT WITNESS JOURNAL
She has extensive medicolegal experience since 2009,
including personal injury, medical negligence and reports
for the GMC.
Contact: Kayleigh Shough, PA
Tel: 07767 329 802 F: 01760 336 968
Web: www.cambridgeneurology.co.uk
Address: Cambridge Neurology, FAO Kayleigh Vine,
115 Southlands, Swaffham, Norfolk, PE37 7PG
Area of work: Cambridge, Norfolk surrounding counties &
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JUNE 2024