As the sense of smell fades, does death come closer?

By Dennis Thompson

HealthDay Reporter

MONDAY, April 29, 2019 (HealthDay News) – They say the nose knows it, but can a loss of smell signal impending death?

Maybe, say the researchers.

They discovered that a bad sense of smell was associated with a 50% higher death risk over the next decade for adults over 70 years old.

Although the study did not prove the cause-and-effect relationship, this association is sufficient to prompt some experts to question whether the sense of smell in the elderly should be tested alongside their other vital signs.

"I would not be surprised that one day, the sense of smell is included in a simple assessment, in order to see if this important human sense is affected," said Dr. Honglei Chen, principal investigator, professor of Epidemiology and Biostatistics at Michigan State University.

Nearly 1 in 4 aging Americans suffers from a loss of their sense of smell, researchers said in briefing notes.

In addition, research has linked the loss of smell to the risk of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and some dementia, Chen said.

But Chen and his colleagues suspected that the sense of smell could have broader consequences on the health of older people than just a predisposition to brain problems.

They analyzed data from nearly 2,300 adults aged 71 to 82 who were followed in a larger health study.

Participants had a brief test of odor identification as part of a battery of health exams. They were then followed for about 17 years, to see what diseases might affect them.

It is unusual for older people to have their sense of smell tested, said Vidyulata Kamath, assistant professor of psychiatry and behavioral science at the Johns Hopkins University School of Medicine in Baltimore.

"We notice that our vision is changing.There is evidence that our hearing is changing, but studies have shown that there is a considerable gap between the reporting of their sense of smell by people and their score. to objective tests, "said Kamath. "There are a significant number of adults who are unaware of the olfactory system [sense of smell] loss."

Kamath wrote an editorial accompanying the study. Both are published on April 30 in Annals of Internal Medicine.

Even worse, the new study showed that a loss of odor actually prevented death.

"We found that compared to people with a good sense of smell, people with a weak sense of smell had a higher risk of death by about 48% in the tenth year and a 30% higher risk in the thirteenth year, "said Chen. "As we are talking about an older population, this risk is not minimal at all."

The association was largely limited to people who reported good or excellent health at the beginning of the study, Chen said.

"This suggested to us that it was an early and probably sensitive marker for ongoing health conditions that might not be recognized regularly by the participants themselves," Chen said.

In addition, the researchers found that conditions already related to bad smell represented only about 28% of the higher risk of death. This includes 22% of the risk attributable to neurodegenerative diseases and 6% related to weight loss, the researchers reported.

"When you lose your sense of smell, it can have downstream effects on your appetite," said Kamath. "You may not be able to eat as before You may have reduced food intake This could potentially lead to a change in body weight and a change in your nutritional status."

But this leaves unexplained more than 70% of the higher mortality associated with a bad sense of smell, Chen said.

According to some theories, the wrong sense of smell could be linked to these deaths, but no real answers, said Chen and Kamath.

People can die in a fire because they do not smell smoke or die from food poisoning because they do not feel that their meal is cut off, but "these events are quite rare at beginning in the general population, "Chen said.

People who eat poorly because of their sense of lost sense of smell may also be at increased risk of developing heart disease, due to malnutrition or the consumption of unhealthy junk food with a keen taste, Chen added. They could also have been exposed to a toxic environmental pollution that would have hurt their ability to smell and cause other damage to their body.

Although these results are interesting, it is still too early to include scent exams in the regular checkups of older people, agreed Chen and Kamath.

"I do not think we have already done the study to show that it improves clinical practice," Kamath said.

Part of this research will be figuring out what's behind the 70% unexplained deaths, Chen said.

"We need to know what these health consequences are before we can make recommendations," he said.