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Failing sense of smell might suggest the onset of dementia, a recent study published in the journal JAMA Neurology has shown.
Research was conducted by experts at Mayo Clinic in Minnesota, and focused on 1,430 men and women, with the average age of 79 years.
The participants, who hadn’t initially exhibited any signs of brain disease, were required to take a smell identification test, in order to determine if their olfactory system was functioning normally.
They were asked to detect 12 odors, 6 of them pertaining to food items (cinnamon, chocolate, banana, onion, pineapple and lemon) and 6 others coming from other sources ( roses, soap, turpentine, paint thinner, petrol and smoke).
Following these initial tests, completed as part of the Study of Aging between 2004 and 2010, researchers continued to monitor the subjects, every 15 months, for a period of 3 and a half years. Gradually, 250 of the participants developed mild cognitive impairment (MCI), which is usually one of the earliest signs of dementia.
Indeed, eventually 64 of the people who had experienced trouble remembering, concentrating, taking decisions or learning things were found to have been affected by dementia.
Of this group, 54 of them had Alzheimer’s disease, a progressive and irreversible brain disorder which accounts for approximately 60% to 70% of all dementia cases.
Experts noticed that those who had scored badly during the scent test were also the ones who faced the highest likelihood of developing cognitive issues, especially amnesic ones, their risk being 2.2 higher in contrast with the rest of the participants.
Moreover, patients who were affected by permanent anosmia (inability to perceive odors) had a much more elevated risk of being affected by Alzheimer’s disease.
It may be because brain degeneration disrupts the ability to store memories related to scents, and also diminishes the capacity of recollecting and retrieving this information when faced with a smell that has been encountered before.
While the findings are indeed well worth taking into account, it must be noted that so far researchers haven’t conducted brain MRIs also, to fully comprehend the potential link between an impaired sense of smell and neurodegeneration.
After all, aging causes deterioration across all the senses, and the majority of elderly people undergo olfactory loss, due to various other reasons. Therefore, as study authors explained, further analysis should be carried out in order to test this theory more thoroughly.
Meanwhile, Dr. Doug Brown, director of research and development at the Alzheimer’s Society, has declared that the new scientific paper is in accordance with other prior studies, which had also suggested that failing sense of smell is one of the first indicators of this brain disorder.
If the hypothesis is proven correct, this might mean that elderly patients who face heightened risk of developing dementia might be screened more effectively.
Through the use of noninvasive and cost-effective Brief Smell Identification Tests (B-SIT), in conjunction with other examinations, physicians might identify early warning signs of cognitive decline, so that those who have such symptoms can receive the treatment they require much sooner than before.
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