Acute loss of smell predicts dementia and Alzheimer’s

decreased sense of smell Over time this can predict not only loss of cognitive function, but also structural changes in areas of the brain that are critical for Alzheimer’s disease and dementia in general.

This is the main conclusion of research led by the University of Chicago Medicine that provides “another clue” as to how a rapid decline in the sense of smell It’s a “really good” indicator of what’s happening structurally in specific areas of the brain, says Jayant M. Pinto says.

The relationship between smell and dementia

based on Follow-up Study of 515 Older AdultsPosted in Alzheimer’s and Dementia: Journal of the Alzheimer’s Association,


Memory plays a fundamental role in human ability recognize the smell And the scientific community has long known the connection between smell and dementia, recalls a statement from the University of Chicago.

plates and tangles of proteins—which characterize tissue affected by Alzheimer’s usually appear in the olfactory regions of the brain and those associated with memory before developing into other parts of this organ. However, it is still unknown whether this damage is the cause of a person’s reduced sense of smell.

Pinto and his team wanted to see if it was possible to identify changes in the brain that are related to loss of smell and cognitive function over a person’s time.

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“Our idea was that people with a rapidly diminishing sense of smell over time they will be in worse shape -and they would be more likely to have brain problems and even Alzheimer’s – than those in whom it gradually diminished or retained a normal sense of smell”, details Rachel Sweat.

Similar risks to the APOE-e4 gene

The team used anonymized patient data from Rush University’s Memory and Aging Project, started in 1997, to investigate chronic conditions of aging and neurodegenerative diseases, such as Alzheimer’s.

Patients undergo annual tests to check for certain smells, their cognitive function, or their ability to identify symptoms of dementia; some were made an MRI.


In their observations, the scientists found that a rapid decline in a person’s sense of smell during periods of normal cognition predicts Several features of Alzheimer’s disease, including a decrease in gray matter In areas of the brain related to smell and memory, there is an increased risk of impaired cognition and dementia.

In fact, the risk of losing the sense of smell was similar to having APOE-e4 gene carrierA known genetic risk factor for developing Alzheimer’s.

the changes were most noticeable primary olfactory regionThat includes the amygdala and the entorhinal cortex, a key input to the hippocampus, a key site in Alzheimer’s.

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“We were able to show that volume and size of gray matter People with a sharply decreased sense of smell had fewer areas of olfaction and memory than those with less severe olfactory decline,” summarizes Pinto.

odor as a risk factor

According to the researcher, this study “should be taken in the context of everyone”. Known Risk Factors for Alzheimer’sIncluding the effects of diet and exercise.

“The sense of smell and its changes should be an important component in the context of what” Several factors We believe that health and aging affect the brain.

Dementia, Alzheimer's.

For Pacina, if people aged 40, 50 and 60 who are most at risk from the startYou may have enough information to enroll them in clinical trials and develop better drugs.

However, scientists believe some limitations of the study, such as the fact that the participants had only one MRI, thus missing data to indicate when structural changes began in their brains or how quickly brain regions shrank.


Rachel R. Pasina, S. Duke Han, Kristen E. Roblewski, Martha K. McClintock, Jayant M. Pinto. Rapid olfactory decline during aging predicts dementia and GMV loss in AD brain regions. Alzheimer’s and Dementia (2022).


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