Smell Deficits Linked to Increased Mortality Risk in Older Adults

The risk comes particularly from neurodegenerative and respiratory diseases.

Grustock/Shutterstock

A diminished sense of smell may be more than an inconvenience for seniors; it may be a warning sign of increased mortality risk.

A new study monitoring more than 2,500 older adults found those with smell impairment faced a 68 percent increased risk of death within a six-year period, with neurodegenerative and respiratory conditions among the leading causes of death.

In older adults in the United States, the frequency of anosmia, the complete loss of the sense of smell, increases with age, with rates ranging from 13 to 25 percent among those 60–79 years old. The prevalence of anosmia and other smell impairments can be as high as 39 percent in those aged 80 and above.

Each Incorrect Response Increases Risk

While the study highlights the importance of olfactory health for longevity in people aged 60 and above, researchers emphasized that reduced sense of smell is a marker for, rather than direct contributor to, increased mortality.

The study, recently published in JAMA Otolaryngology–Head & Neck Surgery, used the Sniffin’ Sticks odor identification test, which evaluated participants’ ability to identify 16 different odors. Researchers found that getting more odor identification questions wrong meant a higher chance of dying within six and 12 years.

For each wrong answer, the risk of death increased by 6 percent after 6 years and 5 percent after 12 years.

Overall, the inability to smell raised mortality risk by 68 percent after six years and 67 percent after 12 years. By 12 years, the link between smell deficits and dying decreases as participants are older and age becomes a greater risk of death than smell.

Among all participants, nearly 18 percent died within six years, and about 38 percent died within 12 years.

Each incorrect answer on the odor test was linked with a nearly one-third greater risk of dying from neurological and respiratory diseases at six years.

Researchers analyzed data from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), involving 2,524 participants with an average age of about 72 years, who were evaluated from 2001 to 2004 and followed up for up to 12 years.

Mortality rates were monitored through the Swedish National Cause of Death Register, with researchers analyzing the relationship between olfactory ability and mortality while adjusting for factors such as age, sex, education, and smoking.

What’s Behind the Connection?

“Olfactory impairment may be linked with mortality through multiple mechanisms,” the authors wrote. It may impair people’s ability to detect danger like smoke and spoiled food, though death from these incidents are rare. It may also be a sign of inflammation and neurodegeneration.

Loss of smell perception in elderly people “is not an innocuous change,” Dr. Helen Messier, chief medical and science officer at Fountain Life and expert in longevity medicine, told The Epoch Times. “There are very often more serious underlying problems that have to be investigated.”

A decline of the sense of smell is associated with neurodegenerative processes that include Alzheimer’s and Parkinson’s, “the presence of which is certainly associated with increased mortality,” she added.

The olfactory bulb and related brain areas are often among the first regions in the brain to be affected by the neuropathological changes associated with Alzheimer’s.

Messier said that loss of smell may also indicate inflammation, metabolic dysfunction, and more advanced cognitive decline—“all factors associated with an increased risk of death at an earlier age.”

Olfactory decline, besides serving as an early non-motor symptom in neurodegenerative disorders, may also indicate other systemic conditions, Dr. Isabella Park, associate medical director and director of geriatrics and palliative medicine at Northwell Long Island Jewish Forest Hills, told The Epoch Times.

These include “cardiovascular disease and diabetes, potentially reflecting shared underlying pathophysiological mechanisms such as inflammation or microvascular changes,” she said.

Microvascular changes affect the small blood vessels and can damage the heart and brain. These changes may lead to atherosclerosis and a reduction in capillary density, impairing blood flow and oxygen delivery to these organs.

Inflammation, a natural response to tissue damage, also plays a role in neurological and cardiovascular diseases. Chronic low-grade inflammation, often associated with aging, can contribute to the development and progression of these conditions.

Beyond serving as a marker for other conditions, smell loss directly impacts quality of life and safety.

“Seniors with a lack of smell may lose appetite, which may lead to them not being able to receive enough vitamins and food,” Messier said. “It also leads to them not being able to identify gas, spoiled food, or smoke, which increases their risk of being harmed.”

At six years, dementia accounted for 23 percent, frailty for 11 percent, and malnutrition for 5 percent of the link between smell deficits and mortality.

But at 12 years, frailty was the only significant cause of death.

Malnutrition and frailty can significantly increase mortality risk in seniors by impairing the body’s ability to cope with stress and recover from illness, leading to complications and increased vulnerability. Both conditions weaken the immune system and reduce physical reserves.

The researchers found that lower health scores is also linked to higher risk of dying from respiratory issues—an 87 percent increase within six years, as well as a 50 percent higher risk from cardiovascular problems.

Protecting Your Sense of Smell as You Age

According to Messier, older adults can take proactive steps to maintain their olfactory health.

“Clinical studies show promise for strategies like ’smell training,' such as clove, lemon, rose, and eucalyptus sniffing,” she said.

She added that chronic inflammation, sinus, and some metabolic issues “need to be managed” to help safeguard the ability to detect odors.

Messier also recommended avoidance of smoking, maintaining adequate levels of zinc and vitamin B, and some forms of cognitive exercises or aerobic activity, “all of which may indirectly assist the preservation of sensory systems and resilience as we age.”

Park noted that health care providers should also counsel patients and caregivers on compensatory strategies, “including enhanced food safety practices and the use of visual and textural cues to maintain adequate nutrition.”

Messier pointed out that olfactory decline is emerging as a quiet but significant biomarker of overall healthspan.

“It’s a reflection of the brain, immune and sensory systems all at once,” she said. “The same way one monitors changes in cognition or gait, recognizing and tracking changes in smell can enable us to intervene much earlier and much more effectively.”