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Tag: sense of smell

Published on Leave a comment on Loss of Smell from A COVID Infection Can Linger For At Least Two Years

Millions of us have had a least one COVID infection. Many suffered a loss of smell during the infection. A recent study by NYU Langone researchers found that the loss of smell can linger for at least 2 years after the infection. And even if you thought that your smell was never impacted or that it has recovered, it actually may not have fully recovered, but only partially recovered.

Among the 3525 participants in the study that reported a loss of smell during a COVID infection - 80% still  had not fully recovered their sense of smell 2 years later, and for 23% it was severely diminished or lost. Interestingly, 66% of persons who originally had a COVID infection, but did not notice any smelling issues, also scored abnormally low on the evaluation done 2 years after the infection.

It can be said that their sense of smell has dulled (olfactory dysfunction). This reduced ability to smell is called hyposmia. Researchers administer a 40-odor test to persons to determine their smelling ability. To help recover the sense of smell, vitamin A supplementation and olfactory training are being tried.

From Science Daily: Millions could be living with hidden smell loss after COVID without knowing

People who suspect that their sense of smell has been dulled after a bout of COVID-19 are likely correct, a new study using an objective, 40-odor test shows. Even those who do not notice any olfactory issues may be impaired. ...continue reading "Loss of Smell from A COVID Infection Can Linger For At Least Two Years"

Published on Leave a comment on Loss of a Sense of Smell and Diseases

How's your sense of smell? Hopefully, it's good. A recent study found that a loss of smell is linked to 139 diseases or medical conditions!

The loss of smell (olfactory dysfunction) appears to be an early sign of all sorts of neurological and bodily diseases. The researchers found that the 139 medical conditions are also associated with inflammation (that olfactory loss and inflammation co-occur).

For example, loss of a sense of smell is an early symptom of both Alzheimer's disease and Parkinson's disease. It can be found in youth long before they exhibit symptoms of schizophrenia. It also precedes depression, major cardiac events, multiple sclerosis, early death, and even memory and neurological impairment.

Interestingly, the study authors point out that there is research showing that pleasant scents can decrease inflammation, and thus possibly improve brain health, including memory. The pleasant scents can be viewed as "therapeutic olfactory stimulation" or "olfactory enrichment". About 20 studies have been done showing that increasing olfactory stimulation (sniffing various scents, including essential oils) can improve memory.

Research done on animals shows that some scents have anti-inflammatory action, for example, eucalyptol, lavender, ginger, carvacrol (found in oregano, thyme, and sage), Shirazi thyme, limonene, and mango. Diet can also have an effect, as well as environmental factors (e.g., smoking, some medications, stress, alcoholism, nasal passage blockages).

From Science Daily: Smell loss linked to 100-plus diseases

Researchers from the Charlie Dunlop School of Biological Sciences, in collaboration with The Oxford Research Centre in the Humanities, reveal a powerful link between olfactory loss and inflammation in a staggering 139 medical conditions. This research -- led by professor emeritus Michael Leon, and researchers Cynthia Woo and Emily Troscianko -- emphasizes a little-known but potentially life-altering connection: the role our sense of smell plays in maintaining our physical and mental health. ...continue reading "Loss of a Sense of Smell and Diseases"

Published on Leave a comment on Is A Poor Sense of Smell In Older Adults A Sign of Deteriorating Health?

A number of studies have found that a poor sense of smell in older adults is linked to health problems (especially Parkinson's disease and dementia) and death. Now a recent study found that a poor sense of smell in older adults is associated with an almost 50% increase in their risk of dying within 10 years—especially in individuals reporting good health. In other words, a poor sense of smell is an early sign of deteriorating health, even when it is not apparent yet to the person.

Researchers at  the Michigan State Univ. College of Human Medicine  followed 2,289 persons (aged 71 to 82) for 13 years. The generally healthy persons took a smell test of 12 common odors (e.g. onion, soap, gasoline, lemon, chocolate and rose) at the start of the study, and were scored as having good, moderate, or poor sense of smell. After 13 years 1,211 of them had died. The researchers then looked to see if there was any association between scores on the smell test and their risk of death at various points over the 13 years.

No association was found at the three- or five-year mark of the study. But those with a poor sense of smell had a 46 percent higher risk of dying by 10 years and a 30 percent higher risk by 13 years, when compared with the older adults with a good sense of smell. The researchers believe the risk was lower at 13 years because so many of the participants had already died - whether their ability to smell was initially good or poor. So how to interpret the study results? It appears that a poor sense of smell may be a sensitive early sign of deteriorating health, even when it is not apparent yet.

From Medical Xpress: Poor sense of smell associated with nearly 50 percent higher risk for death in 10 years  ...continue reading "Is A Poor Sense of Smell In Older Adults A Sign of Deteriorating Health?"

Published on Leave a comment on Are You Both A Good Navigator And Have A Good Sense of Smell?

Do you have a good sense of smell and are also good at navigation? A series of studies by Canadian researchers found that they are linked - and that these abilities are located in overlapping brain areas - the orbitofrontal cortex and hippocampus. The Canadian researchers found that both the cortical thickness of the left orbitofrontal cortex and the right hippocampus were bigger in the better smellers and better navigators (the subjects had MRI scans).

The researchers say the findings support the view that olfaction (the sense of smell) evolved to aid navigation - this hypothesis is called the olfactory spatial hypothesis. For example, all animals use chemical cues to navigate, to find food, to avoid being preyed upon, while in contrast vision and hearing are not present in all animals. In humans, good navigators have what the researchers call "spatial memory". From Laura Sanders at Science News:

People who have a good sense of smell are also good navigators ...continue reading "Are You Both A Good Navigator And Have A Good Sense of Smell?"

Published on Leave a comment on Lose Weight If You Can’t Smell Your Food?

The following is a study with weird results, really weird results. And it makes me think of all the times I've heard people joke: "just smelling food makes me gain weight", because we all knew it wasn't true. But what if it was true? .... The results of this study done in mice are that actually smelling the food one eats results in weight gain, and not being able to smell the food results in weight loss - even if both groups eat the same amount of food. And the "supersmellers" (those with a "boosted" sense of smell) gained the most weight of all.

What? How could that be? Yes, the study was done in mice, but perhaps it also applies to humans (the researchers think so). The researchers think  that the odor of what we eat may play an important role in how the body deals with calories - if you can't smell your food, you may burn it rather than store it. In other words, a link between smell and metabolism. Excerpts from Science Daily:

Smelling your food makes you fat

Our sense of smell is key to the enjoyment of food, so it may be no surprise that in experiments at the University of California, Berkeley, obese mice who lost their sense of smell also lost weight. What's weird, however, is that these slimmed-down but smell-deficient mice ate the same amount of fatty food as mice that retained their sense of smell and ballooned to twice their normal weight. In addition, mice with a boosted sense of smell—super-smellers—got even fatter on a high-fat diet than did mice with normal smell.  ...continue reading "Lose Weight If You Can’t Smell Your Food?"