Our sense of smell is something we use constantly.
It can be a first line of defense when it comes to alerting you to spoiled foods, dangerous chemicals or a fire. It detects scents that may soothe you, others that might evoke memories. And, of course, your nose picks up the odor of cooking foods which, in turn, stimulates a salivatory response.
For the most part, we take our sense of smell for granted. Still, the ability to detect and identify odors can decline with age. And when this happens, it could be signs of trouble ahead.
For example, research from the European Society of Cardiology found that the tongues of patients with chronic heart failure look totally different compared to those of healthy people. A typical tongue is pale red with a light white coating. But the tongues of heart failure patients are a deeper red, and the coating is more yellow.
First and foremost, it can indicate a high risk of Alzheimer’s disease and other potential neurological disorders, like Parkinson’s disease. So if I have a 50-year-old who can’t identify specific odors, like peanut butter, coffee or lemon, they are classically going to have an increased risk of Parkinson’s or Alzheimer’s somewhere down the road.
An inability to detect odors and identify them is also linked with frailty.
Loss of Smell as a Risk Marker for Frailty
Researchers out of John Hopkins University School of Medicine recently discovered that the loss of the sense of smell is a predictive marker for an increased risk of frailty as people age.
They used two different measures of frailty in the study. The first was the frailty index, which takes into account 37 different variables related to aging. Second was the physical frailty phenotype (PFP). This is a five-item assessment of gait speed, weakness, unintentional weight loss, levels of physical activity and exhaustion.
The team found that every one-point increase in the ability to identify an odor was associated with a better score on both the frailty index and the PFP. And for every one-point increase in the ability to sense an odor, there was a better score on the PFP, but not on the frailty index.
Conversely, the worse the sense of smell, the frailer a subject was.
One of the reasons a loss of smell may lead to frailty is due to a loss of appetite. When you can’t smell the food and get those salivatory glands working, it makes it difficult to desire food. This can lead to weight loss, malnutrition and weakness.
But more importantly, the connection may be due to a neurological connection.
How Smell, Dementia and Frailty are Connected
As I mentioned earlier, the reduced ability to smell is associated with a higher risk of Alzheimer’s disease. When people have a problem smelling certain scents, they may have a reduced volume in their hippocampus. This part of the brain helps turn short-term memories into ones that are long-term.
People who have trouble smelling could also have a higher burden of amyloid plaque. Maybe even a thinner entorhinal cortex – which plays a role when it comes to forming and organizing your memories.
More importantly, in early Alzheimer’s, neurofibrillary tangles – otherwise known as “tau” – are found in both the olfactory bulb and the entorhinal cortex. (Neurofibrillary tangles are one of the hallmarks of Alzheimer’s disease.)
At the same time, some experts believe cognitive impairment is actually a clinical feature of frailty. That’s because the risk of cognitive impairment or dementia is up to about eight times higher among patients who are frail.
So you have several different things going on here that are all working in tandem against you.
The impaired ability to identify or detect the presence of an odor is linked to both dementia and frailty. Frailty is associated with a higher risk of dementia. And patients with cognitive impairment or dementia are more likely to become frail. It is all connected.
We already get our hearing, eyes and mouths checked out on a regular basis. And since a simple smell test can predict upcoming dementia and frailty, it makes good sense to include it in regular check-ups as you age.
If you want, you can do a “mini-sniff-test” at home. Just put on a blindfold. Then have your spouse, a friend or family member hold food items about five to seven inches below your nose. (Some of the odors people with Alzheimer’s and Parkinson’s can’t detect include cinnamon, coffee, onion, lemon, peppermint, peanut butter and anise.)
If you fail to identify the majority of odors, don’t panic or jump to conclusions. It could be related to other medical conditions.
However, it also indicates that it might be a good idea to pay a visit to your neurologist. He can administer a more detailed test. The one most often used is a “scratch and sniff” test called the University of Pennsylvania Smell Identification Test, or UPSIT.
If you pass it the official smell test, great. If you don’t, further neurological testing can help determine if there are potential issues you should be concerned about.
Just don’t discount what your nose can tell you about your health. It’s another unusual diagnostic tool like the one you learned about in the March 29th issue of Advanced Natural Wellness.
Kondo K, Kikuta S, Ueha R, Suzukawa K, Yamasoba T. Age-Related Olfactory Dysfunction: Epidemiology, Pathophysiology, and Clinical Management. Front Aging Neurosci. 2020 Jul 7;12:208.
Johns Hopkins Medicine. “The nose knows: Study suggests it may be wise to screen for smell loss to predict frailty and unhealthy aging.” ScienceDaily. Jan 2023.
Nagururu NV, Bernstein IA, Voegtline K, Olson S, Agrawal Y, Rowan NR. The association of peripheral and central olfaction with frailty in older adults. J Gerontol A Biol Sci Med Sci. 2022 Dec 11:glac237.
Growdon ME, Schultz AP, Dagley AS, Amariglio RE, Hedden T, Rentz DM, Johnson KA, Sperling RA, Albers MW, Marshall GA. Odor identification and Alzheimer disease biomarkers in clinically normal elderly. Neurology. 2015 May 26;84(21):2153-60.
David D Ward, Janice M Ranson, Lindsay M K Wallace, David J Llewellyn, Kenneth Rockwood. Frailty, lifestyle, genetics and dementia risk. J. Neurol. Neurosurg. Psychiatry. Published Online First: 21 December 2021. Wallace LMK, Theou O, Godin J, Ward DD, Andrew MK, Bennett DA, Rockwood K. 10-year frailty trajectory is associated with Alzheimer’s dementia after considering neuropathological burden. Aging Med (Milton). 2021 Dec 15;4(4):250-256.