Predict frail and unhealthy aging by screening for loss of smell

In a study using data from nearly 1,200 older adults, Johns Hopkins University medical researchers added a growing body of evidence that loss of smell is a predictive sign
of an increased risk of frailty as people age.
Previous research has shown that olfactory dysfunction is a common early sign of brain-related cognitive decline, and the new findings suggest that the connection to vulnerability may be not only in the brain, but also in the nose itself
.

If further research confirms this finding, screening older adults for the ability to smell a variety of odors could be as important
as testing hearing and vision over time, the researchers said.

The findings, published Jan.
10 in the Journal of Gerontology, looked at the prevalence of frailty, an age-related physiological decline syndrome, and two different ways to assess olfactory ability: olfactory sensitivity (the ability to detect the presence of an odor) and olfactory recognition (the ability to detect and name odors).

Olfactory recognition, a central measure of olfactory function, is associated with the vulnerability of the human body and relies on higher-order cognitive processing to interpret and classify odors
.
This suggests that neurological function may help explain the relationship between
odor and weakness.
However, the researchers say the relationship between the ability to detect odors alone without using higher-level neural processes, and the ability to detect odors only and weakness, have not been fully studied
.

"We use our sense of smell to identify the threat of fire, or to enjoy the scent
of flowers in the spring.
But just like sight and hearing, this sensation diminishes with age," said
Nicholas Rowan, MD, associate professor of otolaryngology-head and neck surgery and corresponding author of the study.
"We found that both olfactory recognition and impaired sensitivity function are associated with weakness, which is interesting because it suggests that it's not just your aging brain that's at work, but something peripheral, like something on your nose, that can predict our impending weakness and death
.
" Rowan said that while these findings in older adults add to a wealth of literature suggesting that smell may be a bellwether for weakness and imminent death, the relationship between these unique sensory losses and unhealthy aging over time is unclear
.

What is certain, he notes, is that common consequences of loss of smell include loss of appetite, difficulty monitoring personal hygiene, depression, and inability to detect toxic gases
.
In older adults, this can be associated
with weight loss, malnutrition, frailty, inadequate personal care, and possibly even injuries from gas leaks or fires.

In the United States, the elderly population is expected to double over the next 30 years, prompting efforts to find out which older adults are most likely to experience frailty, an important sign
of impending death compared to those without frailty.
The new study used a standard assessment of frailty (called the frail phenotype, or PFP score) that looked at five indicators: weight loss, exhaustion, weakness, slow walking and low
physical activity.

To study the relationship between frailty and smell, the research team analyzed data
from 1,160 older adults who participated in the National Program on Social Life, Health and Aging between 2015 and 2016.
The mean age of participants was 76 years, and 55.
7% were female
.
Participants were exposed to five odors to measure olfactory recognition and six odors to measure sensitivity levels
.
The results were then matched
to the subjects' frailty scores.

The researchers concluded that every point increase in olfactory recognition and sensitivity scores was associated with a significant and meaningful reduction in frailty, meaning that improvements in smell were associated with
improved health and resilience in older adults.
Conversely, the worse the sense of smell, the more vulnerable the subjects, suggesting that loss of smell may be a measurable biomarker and potential risk factor
for vulnerability in older adults.

As a practical form of health care, Rowan said, the findings mean that olfactory tests can be part of routine screening as a way to identify someone's risk of unhealthy aging and indicate whether additional tests
are needed for cognitive and other conditions.

"We've done tests to assess how good our vision or hearing is, and it's also easy to take a simple olfactory test, just a few minutes, which could be used as a valuable tool
to assess the risk of frail or unhealthy aging," Rowan said.
"For example, if someone fails an olfactory test, the patient may need improved nutrition, or a more detailed neurological or medical examination
.
"

To answer this question, Rowan and his colleagues from the Claude D.
Pepper Center for American Independence at Johns Hopkins University are actively investigating how more detailed olfactory tests can help researchers and clinicians identify physiologically vulnerable older adults
.
Rowan noted that these results are especially important in the context of the COVID-19 pandemic, which has caused millions of people to lose their lasting sense of
smell.
"The really interesting question, however, is what happens to these novel relationships when you try to treat olfactory loss," he said
.

Journal Reference:

1. Nimesh V Nagururu, Isaac A Bernstein, Kristin Voegtline, Sarah Olson, Yuri Agrawal, Nicholas R Rowan.
   The Association of Peripheral and Central Olfaction With Frailty in Older Adults.
   The Journals of Gerontology: Series A, 2022; DOI: 10.
   1093/gerona/glac237