Olfactory Therapy Sounds Like Aromatherapy

Not sure I can believe all this - because you know as they say, extraordinary claims require extraordinary evidence. 

We're talking about a thing called therapeutic olfactory stimulation, also called olfactory enrichment and olfactory therapy. We start with the first study, which says: 

"Olfactory enrichment can improve the memory of older adults by 226%" 

They took 43 people over 60 years old and exposed them to 7 different odorants a week, one per night, for 2 hours, using an odorant diffuser, and then gave them the Rey Auditory Verbal Learning Test where they saw improved scores, and gave them fMRI scans that showed improved functioning in the left uncinate fasciculus as assessed by mean diffusivity.

I'm not a research scientist working in a lab and writing papers, and so the only thing I see here that's a flag is that the study took place during the covid lockdown, and something about social interaction related to the study could definitely improve brain health, because we know that happens. But that also caused lots of other problems like how they had to remove people from the study because their baseline taken in the office might be so different from follow-ups done remotely. 

They do reference a few other studies that support this idea, so I'll just copy directly:  

...olfactory stimulation during sleep deepens slow-wave sleep (Wolfe and Herzberg, 1996; Goel et al., 2005), which is the most restful portion of the sleep cycle, and people report feeling more vigorous the next day after nighttime olfactory exposure (Goel et al., 2005). Odorants enhance normal sleep, and they also improve abnormal sleep at a magnitude similar to that of sleep medication (Hardy and Kirk-Smith, 1995).

Bottom line is, I think we are eagerly awaiting another study, done not-during a pandemic and with a larger group beyond the 43 people participating here. 

via University of California Irvine Center for the Neurobiology of Learning and Memory: Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults. Cynthia C. Woo, Blake Miranda, Mithra Sathishkumar, Farideh Dehkordi-Vakil, Michael A. Yassa, Michael Leon. Frontiers in Neuroscience, 2023; 17 DOI: 10.3389/fnins.2023.1200448 [full text available]

https://doi.org/10.3389/fnins.2023.1200448

Image credit: AI Art - THC Oil Cartridge w Good Image - 2024

But not so fast, we're not done yet. If the results from the above study are found to be credible, that would make the study below a lot more important:

Smell loss is linked to more than 100 diseases in new study

Oct 2024, phys.org

https://medicalxpress.com/news/2024-10-loss-linked-diseases.html

"We now know that pleasant scents can decrease inflammation, potentially pointing to the mechanism by which such scents can improve brain health." The study delves into the methodical tracking of 139 medical conditions associated with both olfactory loss and heightened inflammation, uncovering insights into a shared pathway linking these factors. Olfactory loss, which often precedes conditions such as Alzheimer's and Parkinson's diseases, may serve as an early indicator of disease onset, allowing for more proactive therapeutic approaches.

By showing how olfactory enrichment can mitigate inflammation, this research has laid a foundation for future studies aiming to explore the therapeutic use of scent to address a broader range of medical conditions.

via Charlie Dunlop School of Biological Sciences at University of California Irvine and Oxford Research Centre in the Humanities: Michael Leon et al, Inflammation and olfactory loss are associated with at least 139 medical conditions, Frontiers in Molecular Neuroscience (2024). DOI: 10.3389/fnmol.2024.1455418

https://dx.doi.org/10.3389/fnmol.2024.1455418

On Allergies and Sensitization

Writing about smell will get you thinking about nuisance odors and about folks who think that smells are making them sick. A lot of this has to do with allergies, and allergies can be a tricky thing. There is no threshold for the amount of a thing that will elicit a reaction, and so allergies tend to be modulated by our own minds, at least to some extent. In other words, if you’re stressed, or if you’re thinking way too much about these allergies and their allergens and the environment where they come from, you may amplify the effects, and you may start sneezing or scratching at the most miniscule of exposures.

The way allergies work in the body is pretty damn confusing. There’s different kinds of allergies, some are hardwired, we might say, and some are ‘learned’ by the body. Some allergies can be deadly, like a shellfish allergy that closes your throat. Some can be just annoying, but won’t kill you or send you to the hospital (unless your body gets so hijacked by your own histamines that you smash your head into a wall).

All this being said, when I came across this short explanation on how allergies work, and I found it to be somewhat comprehendible, I thought I should repeat it here.

Most chemicals and their metabolic products are not sufficiently large enough to be recognized by the immune system as a foreign substance and thus must first combine with an endogenous protein [something that comes from inside the body not outside, endo- vs exo-] to form an antigen (or immunogen). Such a molecule is called a hapten. The hapten-protein complex (antigen) is then capable of eliciting the formation of antibodies. Subsequent exposure to the chemical results in an antingen-antibody interaction, which provokes the typical manifestations of allergy that range in severity from minor skin disturbance to fatal anaphylactic shock.

-Essentials of Toxicology, Casarett and Doull

Got all that? The “allergic reaction” is really an antigen-antibody reaction. It is your body fighting an intruder, and you are the collateral damage.

***

Please take a look at another post called The Dangers of Smell and Perfumes in the Workplace but it’s based on this article: perfume in the workplace, which is an interesting look inside the work of an HR worker who has to deal with employees complaining about their smelly coworkers, and soothing the hypersensitive worker who thinks their coworker’s perfume is making them sick (it’s not; unfortunately, it’s your own mind doing that). 

Pheromones Pheromones Pheromones

This ancient secret makes men irresistible to women.

Just kidding. Pheromones might smell good, but they ain’t mind control. Tell people you wrote a book about smells and they’re bound to ask if pheromones really work. The quick answer is “no”. But that isn’t the good answer.

There’s got to be a reason why men (and women) since time immemorial have spent their money on this “secret weapon” of scent. There’s more to this story; the answer isn’t a definitive “no”, but a “very nearly almost ‘no’”. Let’s probe the subject a bit.

Animals do use pheromones, and they do function as mind-control. If you’ve ever crossed the path of a buck in rut, you’ve seen pheromones at work. They aren’t thinking about a damn thing except ‘that a**’. The most popular of pheromones is androstenone. It’s produced by male boar, and it makes the females stand in a “mounting position”, literally controlling the bodies in its presence. There are other pheromones besides those for sex, such as "the smell of fear", an alarm pheromone. One thing to note straight away is that animals sense pheromones in a different way than humans, for they have an extra component in their olfactory system, called the vomeronasal organ. Humans have the physical organ, but it doesn’t seem to work for us as it does for them.

Pheromones will not force humans into a mating stance, but they can most certainly influence our bodies and our behavior with more potency than the smell of fresh bread or brewed coffee. In fact, the most potent smells in this regard are usually bad smells. When looking for physiological evidence of odor-effects, bad smells produce a stronger effect. They can raise the breath-rate, heart-rate, and skin conductance. Across a broad spectrum of subjects, “good” smells will produce neither the same effect nor the opposite. (Sorry, Aromatherapists.) This makes pheromones all the more interesting, because they vacillate between "good" and "bad", as determined by a variety of factors.

Next, pheromones do inform humans on compatibility. Doing the sweaty t-shirt experiment, women tend to have a preference for the smell of bodies with complementary immune systems. In this case, the “pheromone” is a combination of chemicals that, although very similar, is unique to every person. And it doesn’t make women fall on their knees, drooling a puddle of pure estrogen. It’s just a preference, kind of like a strong suggestion, but it’s not mind control.

Now for the nitty-gritty. Pheromones are s special class of smells called semiochemicals. They carry a very strong meaning with them, and for humans meaning is powerful. For humans, and this is primarily where we differ from animals, smell is a learned phenomenon. Nothing is hardwired into our olfactory system. There is no universal template. In theory, we could be taught to find fecal matter as sexually-stimulating as armpit sweat.* The thing is, we are constantly being “taught” about smells, and virtually 100% of the time this is happening unconsciously. (Especially in utero, or during the early years of life, when the majority of our odor education takes place.)

Like all learning, repetition reinforces associations and streamlines response. The more times a smell is sensed in a specific context, multiplied by the “limbic intensity” of that context, the more it appears hardwired.

Coffee in the morning. You aren’t born with that response; it’s reinforced over countless mornings, matched with that exhilaration triggered by the bodyclock upon awakening. Sex. Both males and females produce pheromones, and they are similar, at least in that they both produce androstenone. When you get sexually aroused, you smell yourself, unconsciously, of course. This trigger is reinforced every time you get aroused. This is a blatant example of the relentless lessons of olfaction, but there are other situations where the “smell of sex” is perceived within a sexually-aroused context, matching aroma chemicals with physiological body states. This is what makes a semiochemical. The message is loud and clear, it says “get ready for sex”. But it is not a command.

Humans are cognition wizards. We are so good at using our mental powers, that we can override even the most irresistible physical instincts. We can even change our own genetics. Over generations, some groups of people transformed a gene that allowed them to digest milk into adulthood. Over generations, people differed in the gene that codes the receptor for androstenone (the most popular of pheromones) so that some sense it as sweaty and urinous, some as sweet and floral, and some as nothing at all.

We are in constant co-evolution with our environment, but in ways that go beyond physical interactions. Because our culture can evolve at a rate less constrained by physical limits, the messages it brings can rearrange our instinctual responses. We are not slaves to our bodies. As individuals and especially as groups, we can rearrange the “meaning” of physical information as it is understood by the body (or at least the olfactory system). If you don’t want to smell sex with your pheromones, you can turn it off.**

If you feel like you’ve been looking for love in all the wrong places, you’re better off putting your paychecks somewhere else (like towards a good fragrance, which, by the way, also use pheromones).

On a final note then, there is something to be said for the person wearing the contested mind-control scent. Placebo effect. The very act of wearing a scent, any scent, can raise the confidence of the wearer. And chances are confidence will smell better than synthetic sweat..

*This is not a stretch, when considering male homosexuality, for example.

** Perhaps something can be said here of the lack of body odor secretions from certain Asian populations.