According to new studies, difficulty in identifying common smells such as cinnamon, banana or lemon could signify the risk for progressive brain disorder and be the first sign of Alzheimers disease.
Researchers have already found long back that microscopic lesions that are considered hallmarks of Alzheimers, initially, appear in the brain region, which is the most important to sense smell.
Robert Franks, an expert on odor perception and brain at University of Cincinnati, said “Studies have linked the loss of smell to Alzheimers, though, this is the first to measure the olfactory powers in healthy people and study them for five years, testing all the way for any signs of mental decline.”
About six hundred people were involved in the study in age group of 54 and 100 and were asked to identify a dozen of familiar smells such as rose, cinnamon, lemon, onion, black pepper, chocolate, soap, pineapple, gasoline, smoke and paint thinner.
For each scent, they were given four choices of answers, while also seeing the choices in text. About a quarter of people identified correctly all odors or missed only one. About half of them knew atleast nine out of twelve. But the lowest scoring quarter of people could identify only eight or fewer odours.
The subjects were also given twenty one cognitive tests annually over the next five years. About one-third of these people had mild trouble with thinking and memory.
Individuals who made a minimum of four or more errors in the odour test were more than fifty percent at risk to develop problems, than people with not more than one error. The people who had difficulty in identifying odours were also at greater risk in progressing from mild cognitive impairment to Alzheirmers.
The lead author of Rush University Medical Center in Chicago, Robert Wilson said, “A diminishing sense of smell is not a cause for panic, and not all low scorers went on to have cognitive problems, but, older people should report a loss in smell to their doctor. The problem could even be caused by an infected sinus or a polyp in nose. On the other hand, if the person is very old, and has a good sense of smell, its a very good sign.”