Anosmia, by any other name…

The loss of the sense of smell (anosmia) is these days well-associated with COVID and Long-COVID, but also can simply come with age:

National Institute of Aging | How Smell & Taste Change With Age

…although it can also be something else entirely:

❝Another possibility is a problem with part of the nervous system responsible for smell.

Some studies have suggested that loss of smell could be an early sign of a neurodegenerative disease, such as Alzheimer’s or Parkinson’s disease.

However, a recent study of 1,430 people (average age about 80) showed that 76% of people with anosmia had normal cognitive function at the study’s end.❞

Read more: Harvard Health | Is it normal to lose my sense of smell as I age?

We’d love to look at and cite the paper that they cite, but they didn’t actually provide a source. We did find some others, though:

❝Olfactory capacity declines with aging, but increasing evidence shows that smell dysfunction is one of the early signs of prodromal neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease.

The loss of smell is considered a clinical sign of early-stage disease and a marker of the disease’s progression and cognitive impairment.❞

~ Dr. Irene Fatuzzo et al.

Read more: Neurons, Nose, and Neurodegenerative Diseases: Olfactory Function and Cognitive Impairment

What’s clear is the association; what’s not clear is whether one worsens the other, and what causal role each might play. However, the researchers conclude that both ways are possible, including when there is another, third, underlying potential causal factor:

❝Ongoing studies on COVID-19 anosmia could reveal new molecular aspects unexplored in olfactory impairments due to neurodegenerative diseases, shedding a light on the validity of smell test predictivity of cognitive dementia.

The neuroepithelium might become a new translational research target (Neurons, Nose, and Neurodegenerative diseases) to investigate alternative approaches for intranasal therapy and the treatment of brain disorders. ❞

~ Ibid.

Another study explored the possible mechanisms of action, and found…

❝Olfactory impairment was significantly associated with increased likelihoods of MCI, amnestic MCI, and non-amnestic MCI.

In the subsamples, anosmia was significantly associated with higher plasma total tau and NfL concentrations, smaller hippocampal and entorhinal cortex volumes, and greater WMH volume, and marginally with lower AD-signature cortical thickness.

These results suggest that cerebral neurodegenerative and microvascular lesions are common neuropathologies linking anosmia with MCI in older adults❞

~ Dr. Yi Dong et al.

• MCI = Mild Cognitive Impairment
• NfL = Neurofilament Light [Chain]
• WMH = White Matter Hyperintensity
• AD =Alzheimer’s Disease

Read more: Anosmia, mild cognitive impairment, and biomarkers of brain aging in older adults

How to act on this information

You may be wondering, “this is fascinating and maybe even a little bit frightening, but how is this Saturday’s Life Hacks?”

We wanted to set up the “why” before getting to the “how”, because with a big enough “why”, it’s much easier to find the motivation to act on the “how”.

Test yourself

Or more conveniently, you and a partner/friend/relative can test each other.

Simply do like a “blind taste testing”, but for smell. Ideally these will be a range of simple and complex odors, and commercially available smell test kits will provide these, if you don’t want to make do with random items from your kitchen.

If you’d like to use a clinical diagnostic tool, you can check out:

Clinical assessment of patients with smell and taste disorders

…and especially, this really handy diagnostic flowchart:

Algorithm of evaluation of a patient who has olfactory loss

Train yourself

“Olfactory training” has been the got-to for helping people to regain their sense of smell after losing it due to COVID.

In simple terms, this means simply trying to smell things that “should” have a distinctive odor, and gradually working up one’s repertoire of what one can smell.

You can get some great tips here:

AbScent | Useful Insights Into Smell Training

Hack your training

An extra trick was researched deeply in a recent study which found that multisensory integration helped a) initially regain the ability to smell things and b) maintain that ability later without the cross-sensory input.

What that means: you will more likely be able to smell lemon while viewing the color yellow, and most likely of all to be able to smell lemon while actually holding and looking at a slice of lemon. Having done this, you’re more likely to be able to smell (and distinguish) the odor of lemon later in a blind smell test.

In other words: with this method, you may be able to cut out many months of frustration of trying and failing to smell something, and skip straight to the “re-adding specific smells to my brain’s olfactory database” bit.

Read the study: Olfactory training: effects of multisensory integration, attention towards odors and physical activity

Or if you prefer, here’s a pop-science article based on that:

One in twenty people has no sense of smell—here’s how they might get it back

Take care!

Less Common Alternatives For Oral Hygiene!

You almost certainly brush your teeth. You might use mouthwash. A lot of people floss for three weeks at a time, often in January.

There are a lot of options for oral hygiene; variations of the above, and many alternatives too. This is a big topic, so rather than try to squeeze it all in one, this will be a several-part series.

• The first part was: Toothpastes & Mouthwashes: Which Help And Which Harm?
• The second part was: Flossing, Better (And Easier!)
• The third (and for now at least, final) part will look at some less common alternatives.

Tooth soap

The idea here is simplicity, and brushing with as few ingredients as possible. Soap cleans your teeth the same way it cleans your (sometimes compositionally quite similar) dishes, without damaging them.

We’d love to link to some science here, but alas, it appears to have not yet been done—at least, we couldn’t find any!

You can make your own tooth soap if you are feeling confident, or you might prefer to buy one ready-made (here’s an example product on Amazon, with various flavor options)

Oil pulling

We are getting gradually more scientific now; there is science for this one… But the (scientific) reviews are mixed:

Wooley et al., 2020, conducted a review of extant studies, and concluded:

❝The limited evidence suggests that oil pulling with coconut oil may have a beneficial effect on improving oral health and dental hygiene❞

Source: The effect of oil pulling with coconut oil to improve dental hygiene and oral health: A systematic review

The “Science-Based Medicine” project was less positive in its assessment, and declared that all and any studies that found oil pulling to be effective were a matter of researcher/publication bias. We would note that SBM is a private project and is not without its own biases, but for balance, here is what they had to offer:

SBM | Oil Pulling Your Leg

A more rounded view seems to be that it is a good method for cleaning your teeth if you don’t have better options available (whereby, “better options” is “almost any other method”).

One final consideration, which the above seemed not to consider, is:

If you have sensitive teeth/gums, oil-pulling is the gentlest way of cleaning them, and getting them back into sufficient order that you can comfortably use other methods.

Want to try it? You can use any food-grade oil (coconut oil or olive oil are common choices).

Chewing stick

Not just any stick—a twig of the Salvadora persica tree. This time, there’s lots of science for it, and it’s uncontroversially effective:

❝A number of scientific studies have demonstrated that the miswak (Salvadora persica) possesses antibacterial, anti-fungal, anti-viral, anti-cariogenic, and anti-plaque properties.

Several studies have also claimed that miswak has anti-oxidant, analgesic, and anti-inflammatory effects. The use of a miswak has an immediate effect on the composition of saliva.

Several clinical studies have confirmed that the mechanical and chemical cleansing efficacy of miswak chewing sticks are equal and at times greater than that of the toothbrush❞

~ Hague et al.

Read in full: A review of the therapeutic effects of using miswak (Salvadora Persica) on oral health

And about the efficacy vs using a toothbrush, here’s an example:

Comparative effect of chewing sticks and toothbrushing on plaque removal and gingival health

Want to try the miswak stick? Here’s an example product on Amazon.

Enjoy!