A test for people who
lose their sense of smell in the early stages of Alzheimer's could diagnose the
condition before it strikes.
Scientists have
developed a simple scan which may be able to pinpoint dementia before memory
loss even begins.
The key is in someone's
sense of smell, which starts to deteriorate in many neurological conditions,
from Down's syndrome and schizophrenia to Alzheimer's and Parkinson's disease.
It is why there is a
so-called 'peanut butter test' for people with Alzheimer's who are less able to
sniff out the spread from a distance.
Scientists have
developed a simple scan which may be able to pinpoint dementia before memory
loss even begins. The key is in someone's sense of smell, which starts to
deteriorate in many neurological conditions
However simple smell
tests, according to a team led by Massachusetts General Hospital and Harvard
Medical School, offer an incomplete picture, monitoring the sense of smell only
after it is detected by the brain.
They have developed a
PET scan, called Neuroflux, which avoids the need for a painful biopsy, and
picks up the early signs of Alzheimer's in the nose.
The breakthrough,
found to work effectively in mice, is hoped to lead to a test for all kinds of
memory loss in adults, and not just Alzheimer's.
Lead author Dr Jacob
Hooker said: 'I heard about the peanut test for Alzheimer's years ago.
'A lot of beautiful
research with smell tests has been published with many geared towards making
them more robust, but there are lots of reasons that might not work very well,
for example if someone has sinus inflammation due to a cold.
'By looking more
directly at olfactory sensory neurons between the nose and brain, we can learn
more about the health of the cells that are responsible for smell and extend
into the brain.
The breakthrough,
found to work effectively in mice, is hoped to lead to a test for all kinds of
memory loss in adults, and not just Alzheimer's
'This may provide a
window into the brain and we hope this will ultimately help with early
diagnosis.'
The link between the
nose and the brain explains why people's memories are more strongly triggered
by a smell, like an ex-partner's perfume, than by a photograph.
Previous studies have
shown smell tests can flag up everything from very mild memory loss to
full-blown Alzheimer's disease.
That is because in
many people hyposmia or anosmia – a partial or complete loss of the sense of
smell – happens before cognitive problems in Alzheimer's and years before the
tremors and loss of motor function caused by Parkinson's disease.
Charity Parkinson's
UK said a new test could be a 'significant step forward' in diagnosing the
condition earlier when people are most likely to benefit from treatment.
A PET scan is said by
the researchers, whose study is published in the Journal of Clinical
Investigation, to be better than sniff tests.
Noisy hospitals can accelerate the course of dementia in elderly
patients, experts found last week.
The confusion of busy waiting rooms or seeing different doctors and
nurses can send patients into a rapid decline, according to a major study.
The research, led by
University College London and the University of Cambridge, is the first to show
that becoming acutely confused and disorientated - a condition known as
delirium - can accelerate cognitive decline among patients with dementia.
That is because it
finds initial problems with odour detection and not just the higher-level
processing of smells in the brain.
Biopsies work better
by showing if olfactory sensory neurons have been lost, but are painful and
technically difficult.
MRI scans, also used
to check for these neurons, can be challenging because they detect water and
there is very little in the nose.
The new scan, which
tracks a radioactive molecule injected into the body which flows through the
nose, is hoped to hold the answer.
If its signal reduces
a few months between scans, this is a sign that there are fewer olfactory
neurons.
Dr Doug Brown,
director of research at the Alzheimer's Society, said: 'There is evidence to
suggest that someone's sense of smell could be impacted in the early stages of
dementia.
'This study looks at
a new technique for detecting changes in the brain cells that are important for
our sense of smell, and could help to explore this link further.
'However, because
this method has only been tested in animals and not humans, it is too early to
tell if this test could help improve diagnosis.'
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