American researchers, who followed more than 500 elderly people, found that those who experienced a sharp decline in their sense of smell were nearly twice as likely to develop Alzheimer's disease or dementia, compared to those who didn't. 'lost more gradually.

How Sudden Loss Of Smell Could Be A Sign Of DEMENTIA

Sudden loss of smell has become a hallmark of Covid, but scientists warn it could also be an early sign of dementia.

Studies have previously linked a gradual loss of sense of smell to memory theft disorder.

But new research suggests that a rapid deterioration could be a better indicator.

American researchers followed more than 500 older adults in the United States for about 20 years.

Those who suffered from anosmia for several years were almost twice as likely to develop Alzheimer’s disease as those who lost their sense of smell for decades.

The study’s lead author, Professor Jayant Pinto, from the University of Chicago, said it “provides another clue” to the link between smell and dementia.

He suggested making smell tests as common as hearing and eye exams for older people to screen for the disease.

American researchers, who followed more than 500 elderly people, found that those who experienced a sharp decline in their sense of smell were nearly twice as likely to develop Alzheimer’s disease or dementia, compared to those who didn’t. ‘lost more gradually.



Dementia is an umbrella term used to describe a range of progressive neurological disorders (those that affect the brain) that impact memory, thinking and behavior.

There are many types of dementia, of which Alzheimer’s disease is the most common.

Some people may have a combination of dementia types.

Regardless of the type diagnosed, each person will experience dementia in their own way.

Dementia is a global concern, but is most commonly seen in wealthier countries, where people are likely to live to very old ages.


The Alzheimer’s Society reports that there are over 900,000 people with dementia in the UK today. This figure is expected to reach 1.6 million by 2040.

Alzheimer’s disease is the most common type of dementia, affecting between 50 and 75% of those diagnosed.

In the United States, it is estimated that there are 6 million people with Alzheimer’s disease. A similar percentage increase is expected in the coming years.

As a person’s age increases, the risk of developing dementia also increases.

Diagnosis rates are improving, but it is believed that many people with dementia remain undiagnosed.


Currently, there is no cure for dementia.

But new drugs can slow its progression and the earlier it is spotted, the more effective the treatments.

Source: Alzheimer Society

Although smell is often considered less important than sight and hearing, it provides the brain with vital information.

Memory plays a vital role in the ability to recognize smells, and researchers have long known of a link between the senses and cognitive decline.

Studies have shown that “tangles” of amyloid protein in the brain – a telltale sign of dementia – often appear first in the olfactory and memory-related areas of the brain.

But it’s still unclear whether this damage actually causes a person’s sense of smell to decline.

Professor Pinto and his team wanted to determine whether these alterations correlated with the loss of a person’s sense of smell and brain function over time.

Lead author Rachel Pacyna, a researcher at the university, said: “Our idea was that people whose sense of smell declines rapidly over time would be in poorer shape – and more likely to have brain problems and even Alzheimer’s disease itself – only people who were slowly declining or maintaining a normal sense of smell.

The researchers followed 515 people in their 60s for 20 years, who initially did not suffer from dementia or cognitive problems.

The volunteers all lived in nursing homes and were tested annually for their ability to identify certain smells and signs of dementia. Some also underwent MRI scans.

Their decline in their sense of smell was measured by their smell test scores, which were then charted on a graph. The downward slope trend was labeled as “severe”, “decreased”, “unchanged” or “improved”.

About 100 people in the cohort were later diagnosed with dementia or cognitive impairment.

Those who had no classic symptoms of Alzheimer’s disease but experienced a rapid decline in their sense of smell were 89% more likely to develop memory impairment than those who lost their sense of smell more slowly.

A strong loss of smell was also linked to an increased risk of having a smaller volume of gray matter in the parts of the brain related to smell and memory, compared to those who had a slower decline.

The changes were most evident in parts of the brain used for smell, including the amygdala and entorhinal cortex.

Their risk was similar to those with the APOE-e4 gene, a known genetic risk factor for developing Alzheimer’s disease.

One in four people carry the gene and are three times more likely to develop Alzheimer’s disease than others.

The researchers eventually hope to conduct autopsies on the volunteers, which is considered the gold standard for confirming whether someone has Alzheimer’s disease, to broaden their findings.

And they want to test smell tests in seniors’ clinics, similar to eye and hearing tests, to screen and track early signs of dementia. GOOD

They said the scent tests are cheap, easy to use, and involve smelling a series of sticks that look like felt-tip pens.

Each stick is infused with a distinct scent that individuals must identify from four choices.

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

The team noted that only a fifth of participants underwent MRI scans and those who had only one, meaning they lacked data to determine when structural brain changes began.

And the majority of the volunteers were white, so more research is needed to find out if other groups are similarly affected.

A loss or change in smell or taste was one of three main symptoms of Covid first identified by health chiefs when the virus swept the world last year.

But as the virus has mutated and new variants have taken hold, many infected people no longer report a change in their senses.

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