While it has been widely believed that a loss of smell can be an early indicator of Alzheimer's disease, there hasn't been conclusive evidence proving it.
Now, a study is being carried out at University College London's (UCL) Dementia Research Centre, with support from charity Alzheimer's Research UK and The Perfume Shop.
UCL's Dr Jason Warren, who is leading the research, said: "It has been widely reported that loss of the sense of smell can be an early sign of degenerative diseases such as Alzheimer's.
"And while the study of smell processing in Alzheimer's is still in its infancy, there is some potential for smell to play a part in diagnosing and understanding the diseases that cause dementia."
One element of his work harnesses pupilometry - technology that measures physiological brain responses to stimuli by monitoring pupil dilation.
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Dr Warren has some early results revealing that significant smells in people's lives, such as a favourite perfume, have a strong effect on memory centres in the brain, dilating the pupil markedly.
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Signs Of Dementia
Dr Warren went on: "Pupil dilation like this is of the kind we otherwise see with strong emotional arousal, as occurs in response to pain or loud noises, or indeed romantic interest.
"Women in various cultures over the centuries have used compounds like belladonna to enhance their attractiveness and these also exploit pupil dilation."
He continued: "We only have very preliminary results from this test but, together with mounting evidence in the field, we believe odours may be much better facilitators of memory and emotions than, for example, pictures and trigger quite different parts of the brain.
"These are brain areas that cannot be probed in any other way, yet which are central to diseases like Alzheimer's. And conversely, the loss of smell during diseases like Alzheimer's amounts to a loss in the associated memories, experiences and emotions which those odours unlock."
To help raise funds for Alzheimer's Research UK, The Perfume Shop is this week encouraging customers to share their own memories of special scents in their lives, with each memory being met with a £1 donation.
Alzheimer's Research UK is currently supporting dementia research projects worth more than £22 million in leading universities across the UK.
There are 820,000 people in the UK with dementia and this number is set to rise dramatically in the next 30 years. Alzheimer's disease is the most common cause of dementia, accounting for two-thirds of cases.