Smell may predict loss of cognitive function -

Link between rapid loss of sense of smell and dementia

Smell could be a crucial aid in the early diagnosis of dementia. According to an ongoing study, an increased risk of dementia can be determined at an early stage with the help of appropriate olfactory tests.

In the new study, the team led by Professor Jayant M. Pinto from the University of Chicago investigated whether it was possible to identify changes in the brain that correlate with loss of smell. and cognitive function. The results were published in the specialist journal Alzheimer's & Dementia.

Links between smell and dementia

Memory plays a crucial role in our ability to recognize smells, and the link between smell and dementia has long been known, the researchers report.

For example, the plaques associated with Alzheimer's disease often first appear in areas associated with smell and memory before developing in other parts of the brain, the research team said.

So far, however, it remains unclear whether this damage actually causes the decline of the sense of smell in those affected.

“Our idea was that people whose sense of smell declines rapidly over time are less fit — and more likely to develop brain problems and even Alzheimer's disease — than people whose sense of smell declines slowly or stays normal. “said study author Rachel Pacyna. the University of Chicago Pritzker School of Medicine.

Data from the Memory and Aging project evaluated

The researchers have now tested this hypothesis using anonymized patient data from 515 people from Rush University's Memory and Aging Project (MAP). Since 1997, chronic signs of aging and neurodegenerative diseases such as Alzheimer's disease have been examined in the MAP.

All participants live in retirement or senior communities in Northern Illinois and are tested annually for things like their ability to recognize certain smells, their cognitive function, and signs of dementia. MRI was also performed on some participants.

Smell may predict features of Alzheimer's disease

Data analysis revealed that a rapid decline in a person's sense of smell during a period of normal cognitive ability can predict several hallmarks of Alzheimer's disease.

Deteriorating sense of smell was associated with lower gray matter volume in areas of the brain related to smell and memory, poorer cognitive performance and a higher risk of dementia.

Noticeable changes in certain areas of the brain

Most striking were changes in primary olfactory regions, including the amygdala and entorhinal cortex, which is an important input for the hippocampus, a critical site in Alzheimer's disease, the researchers report.

“We were able to show that the volume and shape of gray matter in the olfactory and memory-related areas of the brain were lower in people with rapid olfactory decline than in people with less severe olfactory decline,” explains Professor Pinto.

Smell test for dementia screening

One of the next things the team wants to study is the effectiveness of using smell tests in clinics - similar to vision and hearing tests - as a means of screening and monitoring older people for signs of early dementia.

“If we could identify people in their early 40s, 50s and 60s who are at higher risk, we might have enough information to enroll them in clinical trials and develop better drugs,” Pacyna said.

The results of the study provide further evidence "that a rapid decrease in smell is a very good indicator of what is going to happen structurally in certain regions of the brain", summarizes Professor Pinto. (fp)

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This text corresponds to the specifications of the specialized medical literature, medical guidelines and current studies and has been verified by health professionals.


Rachel R Pacyna, Duke Han S, Kristen E Wroblewski, Martha K McClintock, Jayant M Pinto: Rapid olfactory decline during aging predicts dementia and GMV loss in AD brain regions; in: Alzheimer's & Dementia (published 2022-07-28), alz-journals.onlinelibrary.wiley.comUniversity of Chicago Medical Center: Rapid loss of sense of smell predicts dementia and smaller brain areas linked to Alzheimer's disease Alzheimer's (published 7/28/2022),

Important Note:
This article contains general advice only and should not be used for self-diagnosis or treatment. It cannot substitute a visit to the doctor.