With the purpose of early detection of some clinical signs of Alzheimer’s disease, researchers from the National Autonomous University of Mexico (UNAM) developed a “smell test”as part of the result of the macroproject New epidemiological, genomic and proteomic strategies in public health, this was announced by the highest house of studies in Mexico.
What is the “smell test for Alzheimer’s”?
In it test to detect Alzheimer’s one is applied threshold concentration of a given odorwhich is already standardized for the population between 60 and 80 years of age.
- Said threshold concentration is obtained from the application of three concentrations: the subthreshold, detected by less than 50% of the population; the threshold, by more than 50% and the suprathreshold, by almost 100%
When a person is made the test to assess the threshold odor, they are asked to smell a piece of paper, explains Rosalinda Guevara Guzmán, from the Faculty of Medicine, who led the project, along with Patricia Severiano, from the Faculty of Chemistry.
If the person perceives the smell, He is given another piece of paper with a different smell, such as roses, tuberose or mint. According to Guevara Guzmán, “if he is able to identify him, his olfactory memory is working.”
Then, the researchers ask the patient to discriminate three smells: two the same and one different.
“This process also has to do with olfactory memory, because you must remember that this smell is the same as this other, and that that one is different from these,” explained the academic.
Later, in several sessions, the olfactory memory test is applied.
In the first of these, the person is given an unfamiliar aroma to smell. He is informed, for example, that it is agave and he is summoned the following week. In the second session, he is given the agave to smell so that he can identify it, and although he sometimes hesitates, he recognizes it. In the third session, she distinguishes it.
“He remembers the smell of agave because he already saved that information. This is the Test more important than being able to remember a scent”, added the researcher.
In other cases, the individual says that they do perceive the smell, but they do not know what they are smelling. He is shown drawings of an apple, a banana, a pear, or an orange, and is asked which figure he corresponds to. If he identifies them, then he got the visual association right, meaning he still has olfactory memory, he said.
According to the researcher, “when a person is in an advanced state of dementia, or already has Alzheimer’s disease, their olfactory memory fails and nothing can be done to fix it.”
Hence, it is important that people around 60 years of age perform the odor test if they notice that their sense of smell no longer works well.
Why does this type of test work?
The olfactory memory It is related to the limbic system of our brain and to the olfactory bulb, a structure responsible for processing the information sent by the olfactory receptors or epithelium inside the nostrils. When these factors are combined, olfactory memory develops, and olfactory stimuli are received through these receptors.
When this occurs, electrical signals are sent to the olfactory bulb, which absorbs the information, breaks it down, and distributes it to different parts of the brain.
This structure connects the perceived aroma with emotions, at the same time that the hippocampus is in charge of linking the smell with a memory in memory.