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Loss of smell may be an early sign of brain diseases (nautil.us)
189 points by jnord 10 months ago | hide | past | favorite | 151 comments



I lived the first 20 or so years of my early life not knowing about smells. I think I already "knew" that I can't smell but I never really appreciated this about myself. I had always been "immune" to smelly things like animal poo, dead animals or whatever (which is abundant since I lived in a remote area). I think the receptors are there because I do feel weird or "sense" that something is wrong when there's smell (only once they told me about it so maybe its just psychological) but I do feel a "sensation" when something that gives out a strong smell is put close to my nose (like perfume and things like that).

However, my brain can't seem to connect which is what. I have no idea what "smelly things" smell like, or what makes a perfume smell "good".

So my family would often asked me to dispose of things that really smell or enter a really smelly room and things like that because they thought I am just "stoic" in this sense. I think they first realized that I don't smell is when I was shocked when they said that my coffee smelt nice. They went "Wait, you don't know coffee smell?". I had always faked my responses when people ask about smell and basically gave awkward smile or grief whenever is appropriate lol.

It didn't dawned on me until recently that I am missing out on a 1/5 a human experience. It also meant that I am very anxious if I am cleaning up properly (do I smell? did I miss a spot?)

Does anyone share the same experience? I wonder how you cope with this issue. I don't have any SO so I don't have a mirror that I can reflect on if the room or myself smell or whatever.


I had somewhat similar experience. It wasn’t until I was around 16 that my parents raised concerns. It came to light for me with my parents coming home and freaking out because I had apparently bumped the stove while they were out and accidentally turned on the gas burner and the entire house apparently smelled of something but I was relaxing in my room without a clue. My parents initially freaked out but later my step dad shared another incident where I had been working on something in the garage and there was gas can that had been tipped over and the whole garage smelled of gas and I had no idea. For the garage incident I could tell something was off around me like spider senses tingling but I couldn’t tell what it was exactly.


> gas burner and the entire house apparently smelled of something but I was relaxing in my room without a clue

Oh yea you just awoken multiple memories of almost causing housefires. I am pretty much banned from cooking, ever.


If electrical cookers aren't possible, you can get hobs with flame supervisors that cut the gas if there's no flame (in fact these are a legal requirement in the UK for new gas stoves). And there are gas leak detectors.


Get an electric or induction stove top. Obviously still possible to leave it on, but you'll get visual cues.


More specifically: Induction doesn‘t inherently provide visual cues–eben better, they shut off themselves if no pan is detected.


From a safety standpoint, induction is the clear winner. Induction stoves shut off when they overheat or when they run longer than 2 hours. They can also keep a present temperature.

But the downside is you'll need compatible cookware, which can be expensive.


I haven’t seen cookware incompatible with induction in the last 15-20 years. Even the cheapest frying pan is now compatible.


Aluminium moka pots aren't. Copper bottomed pots usually aren't. Woks don't really work without a flame. Bain-maries that work on induction tops are about 50:50.


The only thing I miss from gas is my wok. All other cooking on induction is superior. Definitely worth sacrificing a few old pots for. I would love a good wok solution though.


Theres are portable options for professionals:

https://www.bartscher.com/en/Kategorien/Kochen/Induktionskoc...


Bialetti makes excellent moka pots for induction. I find it even better on induction stove to control the flow as you can basically leave it on "5" and coffee slowly pours out. Much harder with real fire.

https://www.bialetti.com/it_en/moka-induction-rossa.html


When my wife and I first started dating I bought her a bunch of expensive stainless steel cookware from a restaurant supply store, that we still have. I recently pondered switching to induction, and went around doing the 'magnet' test on things, only to find that those pots and pans are likely not induction compatible.

So the conundrum is... toss the pans I gave my wife over 20 years ago? Or just stick with electric burners.


Try one of those inexpensive induction burners first. I was excited to try them because of the promises you hear about how much better they are, but once I got one, I quickly grew to hate it for everything except boiling water. The temperature control wasn't fine enough. There were only 12 temperature options and there were big jumps between them. The first temp is 140F and the next is 212F. No simmering, in other words.

If you like to cook (and I'm assuming you do, considering that you bought expensive cookware), I would definitely recommend auditioning an induction burner before you go through the expense and hassle of switching out your stove.


I think the source of your problems is that it was an inexpensive induction burner.

Higher quality ones usually scale more linearly with the power setting.


According to my research, there's only one burner that is very expensive that works with US power levels that allows you to move in 5F degree increments and uses a thermometer for feedback.

Most of the ones you are referring to are European models that work on 240V. If you know of one that works on 120V, please point me in that direction.


I apologize, I didn't take 120V constraint into account. But even in EU, the cheaper induction stoves are significantly worse than the midrange if one is even slightly interested in cooking.


This. It's much easier to get a good portable induction stove (with 2 burners) in Europe because most 220V outlets can handle up to 3,6kW.


And if you have pans that aren't, an induction plate (so you can use the other stuff) is fairly inexpensive as well.


I'd hesitate to recommend this. Why? Because these inserts are both inexpensive and ineffective. ;)

I'd rather pick proper cookware (eventhough the initial investment will be much higher, the "running costs" will be lower).


The initial cost isn't higher if you are buying new pans. New, cheap pans usually work for an induction stove.

But you might not have new pans, nor the money to replace all of them. Especially if you rent and have no control over what stove gets installed when your current one breaks - or just move into somewhere to discover the induction stove. It is kind of like buying toilet paper: It doesn't matter if the 24 pack is cheaper if you only have the money for the 4pack. Running costs don't always matter if you don't have money to invest upfront.

And to be fair, they aren't inserts. They sit between your stove and the cookware. The plate heats up and heats up your cookware, much like your pans heat up to cook your food. It might take slightly longer, but it won't realistically be worse than heating up a cast iron skillet. And you have a stovetop you can use.


Do you feel like taste is a weak sense, or is your sense ~what you think others are experiencing. Since smell is an important factor of taste, do you find food exciting?


As someone with a weak sense of smell, I don't care much for most food. I'm a fan of spicy foods but little else. Perhaps this is because it stimulates other senses. If I'm left alone without being reminded, I'll go 1-2 days without eating on a regular basis.


Same. I love extremely spicy food but otherwise have very little interest in food; I also can't smell sour milk most of the time which is partly why I don't drink milk, and judiciously sterilize my kid's milk bottles. I generally only eat if I start feeling weak or it begins to impact my mood (low blood sugar)


Sounds like a superpower bro.


Luckily I never caused that because I'm usually freaking out too much about it.

However since I can't smell it either, in our new house we got a gas detector. I'm a bit relieved thanks to it.

The positive side is that it also monitors the CO2 and air quality.


I had a friend who couldn't really smell until he got some kind of olfactory surgery. Before the surgery he felt like maybe he was missing out on some stuff like certain tastes or smell experiences (and he had a similar "immunity" to stinks). After the surgery he could smell to some degree and while it was a novelty he didn't feel like it really opened him up to a whole new set of experiences and was a bit underwhelmed. He was more thankful for the ability to breathe through his nose. I think smell is way less impactful than sight or sound, if that makes you feel any better.


> I think smell is way less impactful than sight or sound

I hate to be a downer but smell is incredibly powerful. Vivid memories can rush back from a smell. Food is probably 90% smell and 10% taste.


Sure, it can make for vivid memories if you have a sense of smell.

But if you haven't had a sense of smell for years - or have never really had one - you won't have those memories. If you've never had smells, your brain won't be trained to make those associations. You simply won't feel like you are missing anything.


So are you sayning that without the sense of smell, it would be much easier to keep one's weight in check? :)


Unlikely related. Fat and sugar cravings are pretty basic. I would argue it makes eating healthier things a little more exciting because seasonings and aromas can cover up an otherwise bland meal of tofu and rice.


Seeing the absolute dog shit junk food people eat I'd say they're either already not able to smell or that it doesn't matter much


Yeah sure it does and colors life to some extent but think you had to lose one of your senses and you could choose. Which would it be? Would you lose your hear or vision to keep smell intact?


That's not a fact at all. For example, memories seldom come to me when smelling, like they say they do with everyone.


>Food is probably 90% smell and 10% taste.

Definitely not for me


My mother went her entire 59-year life without a sense of smell. She heavily leaned on my dad to check if the meat was off, if the house smelt before guests arrived, etc. But overall, I felt it was somewhat of a superpower. Who wouldn't love to say they have never experienced the smell of a poorly maintained public toilet or someone else's fart?

She spent about a decade of her life trying to find solutions before giving up and just living with it.


FWIW you mostly can’t smell yourself the same way other smell you. So even if you did stink, you wouldn’t normally notice.

When people smell their pits, they can tell when it stinks, but they have to really get their nose in there, whereas other people smell you from 10 feet away.


Core fear unlocked.


33 years old and I have had this issue for as far as I remember.

As for hygiene, I learned about that late (thanks to a boss who had the courage to speak to me about it), and now I just strictly follow the same daily routine. No more being complacent with showering, and I always wash my clothes every day regardless.

It worked well so far. But when it comes to changing the bed sheets or cleaning the toilet, I tend to let my wife handle it. Because smells does not mean anything, so for me as long as it is white and without stains, it is clean.

That said, I noticed lately that I sometimes actually smell things, but it is very random and episodic, like a few seconds every few weeks or so. So now I am wondering what is actually going on and if that may be curable in my case.


As I mentioned above, make sure you get your sinuses checked for nasal polyps and if you have any, ask your doctor if cortisone nasal spray can be used to shrink them.


I lost 90% of my smell due to a traumatic brain injury (including face/nose damage), so I've lost the ability to smell nuanced things and taste subtle flavors.

It was hard at first, but I've since coped by using things with strong smells that I can still recognize. Coffee, lemon, copious amounts of cumin and parmesan, cinnamon, vanilla, etc.

What's interesting is that I can still "remember" the original smell, but it doesn't smell the same anymore.

As far as personal hygiene/cleaning...I kind of just gave up on it. I don't really care if someone tells me I smell. That's a them problem now, and I have much worse things to worry about after my brain injury.


No need to be anxious. Just use soap and water and you're fine. I personally use fragrance-free soap.

And above all, please don't overcompensate and become one of those people who drenches themselves in perfume and air fresheners thinking people like it. They don't and there is a reason why you see signs at hospitals and schools saying to please not use that stuff.


Same experience here. I can once in a while smell things, but it doesn't last long, and I can't correlate the smell a perfume is supposed to represent to what it actually represents (so, a perfume that smells like roses smells like something, but I can't correlate it with the actual smell of roses, because I don't know how they smell). There are some smells that are quite strong and I can identify, like alcohol, fuel, acetone, but I wonder if what I call 'smell' in those cases is just a chemical reaction you get from the abrasive? properties of those things, rather than actual smell.

I cope with it in my own case by being thorough in my own cleanliness - I shower and use perfume (three sprays!) every time I have to leave my house. For other things I rely on my SO.

I'm a bit of a hypochondriac but I've lived like this for 30 years so I guess if I was having some kind of mental degradation it would have been noticeable already!


Three sprays of perfume means you're probably overcompensating in the opposite direction. Not to make you anxious, but being around overpefumed people gives me headaches - hate it.

Daily showers, deoderant, and shower after workout or heavy sweat should be more than sufficient.


And the one spray of perfume is best done towards the hair: it diffuses slower


Did you have your sinuses checked for nasal polyps? I frequently lost my sense of smell when I was younger, and if I had known erlier, I would have started using cortisone nasal spray, which can help reduce polyps significantly (of course consult your doctor, first).


I'll talk to my physician about this soon, let's see!


I was similar to you (maybe not to that extreme) and I don't see zinc mentioned in this post.

I did have a minimal sense of smell, as in I could faintly smell perfumes if I sprayed it on my nose but often not animal feces or similar.

I started supplementing zinc because I suspected I was deficient in it and in about two weeks of taking 25-40mg per day (be careful, 40mg is the upper limit) I started smelling things properly.

It got to a point now after a few years that I can tell what happened in a room in the previous 30 mins when I step in.

There are upsides (smelling the sea) and downsides (dirty humans are truly something) but I love every minute of it.


> what makes a perfume smell "good"

Which is very subjective. I personally can't handle it, in the past I've even got headaches just from a couple perfume bottles standing around in the same room. I had to get rid of a perfumed shaving soap because it was a guaranteed headache and smelled like a chemical plant to me, while others just shrugged and said it's fine.


Perfumes, some deodorants (e.g Axe), and candles are the worst for me. I have to stop breathing and protect my eyes when entering department stores, for some reasons they often have a large area full of perfumes directly at the entrance.


Wow, then I can't imagine what it is like for you at airports where you are forced to go through the duty-free section with all the perfumes...


Yeah, it’s the same. Stop breathing, trying to walk fast to the other side.


Congenital absence of smell is a medical issue, and you may want to consider speaking to a physician.

For example: it can be caused by Kallmann syndrome, which is associated with other midline defects, especially of the hyothalamus (delayed puberty) or palate (resulting in a cleft). It can affect the eyes, ears (hearing loss), and kidneys.


If you bring this up to a doctor, like I have countless times, they just won’t care. And I’m already on disability for two illnesses.


The problem is that that's a bad doctor, and there's an abundance of those. A good doctor would care.


I lost my sense of smell temporarily because of a Covid infection, and it was gone completely - I could stick my nose into a jar of ground coffee and not smell a thing. Funnily enough, they say that if you can't smell, your sense of taste is also impaired, but I could taste food just fine...


Had the same, but both taste and smell... anything eaten was just tasteless goo for maybe 6 weeks, no point in fine cuisine. I tested myself daily with sniffing a bottle of 52% home made slivovitz, it was like breathing mountain air, no reaction to even rather concentrated alcohol vapors.

Weird times... I'll never know if my smell came back 100%, or just some fraction of it. In fact, it took good additional 6 months to get my personal perfume to smell nice again, while normal smells kid of came back, this was a litmus paper for me that I am not 100% there yet.

Btw you can lose smell easily permanently, all it takes is 1 good hit in the nose. Nerves going through the skulls go through these tiny pores in the bone, and if the nose cartilage moves enough suddenly they all get severed/chopped. Doctors are quite familiar with this, no way to get this repaired.


Would you have some sources/info regarding the nerves part? This would explain quite a lot personally.


My sense of smell is weak, my SO's is particularly strong.

Net effect is that we eat different things, because I like "garbagey" tastes like seaweed, anise, liquorice, anchovies etc. and she can sense if dairy or fruits/vegetables will give her food poisoning past expiration date.

As for hygiene I stick to a routine and rely on other senses - if I'm feeling sort of sticky then it's definitely time to bathe.


I wasn't born with it, but after catching Covid my sense of smell got for lack of a better term "muffled". Some things merged together. I could still "smell" shampoo and hand sanitizer, but they smelled identical to me and unlike either what they used to smell like or anything I could really place. There were quite a few times when I'd smell something and have no clue what it was because the scent was unlike anything I'd ever smelled before. During that time I was definitely self-conscious about how I might smell because I just couldn't tell.

Since then I think it's mostly recovered. Things smell how I think they should most of the time. But I always wonder if there's something out there that I'll smell completely "wrong" some day because the receptors for that particular smell just never recovered.


I don't have any personal experience with this, but Simon Tatham (creator of the PuTTY SSH client) has written about having anosmia: https://www.chiark.greenend.org.uk/~sgtatham/smell.html


Yeah, same thing for me. I was probably 20 or so when I really understood that I had no sense of smell. It was much later when I realized that this was a gap in my version of human experience. As these things go it seems like not much of a disadvantage though.


> As these things go it seems like not much of a disadvantage though.

Well I think it’s more that you are used to. I’ve lived my whole life with only one eye (amblyopia) and it never ever bothered me until the boom of 3D movies which looked like standard movies for me. Plus, I’ve always been bad at catching balls but that’s just something I avoided as much as I can.


People without smell have a far higher chance of dying (statistically) in any given year than people with smell.

This article suggests that loss of smell might be an indicator of various brain diseases (which then might also kill you). However, other leading theories are that without the ability to smell, there is a much higher chance of eating bad food or toxins, contaminating things with faeces or chemicals, or otherwise harming yourself in ways smell would have prevented.


I got extremely sick in 2017 for about a week. Went through about 6 boxes of tissues in that short time period and was barely able to feed myself. Only months after when someone was vaping near me did I realize I wasn't able to smell.

Only after a few years after long and intense cardio I would sometimes regain some sense of smell for about 20 minutes. Now in the last month seems to be coming back more permanently.

I'm someone who spends a lot of money on expensive perfumes like Creed and regularly burn incense in my house.

I honestly didn't feel like I was missing out on much with no sense of smell, definitely did not feel like I was missing 1/5th of the human experience. It really didn't bother me and I never went to a doctor for it. That said, I'm glad the sense is slowly coming back again.


Couldn’t smell much of my life. Later on got diagnosed with autoimmune Sjogrens. Seems like it could be related.

https://creakyjoints.org/living-with-arthritis/symptoms/sjog...

Much later in life I got migraines really bad. During which all my senses went into overdrive. Sense of smell was vastly better than those around me.


After covid I lost my sense of smell, and for almost 2 years my smell only recovered to about 5% of my original.

Honestly, I thought about it and I'm perfectly fine not being able to smell for the rest of my life. On the flip side, I'm actually happy I'm not impacted by unwanted smells in my environment.

Having smelt before, I don't miss it, but if I was born without it I would always wonder. Well let me tell you there's not much to miss.


Not being able to smell sucks. I was able to smell for the first 20+ years of my life and then lost it.

After years of going to doctors getting treated for polyps and allergies and all kinds of things I was diagnosed with Samter's Triad.

I know you have this since birth and it most likely is not what you have, but other people with similar symptoms may want to look into that, because not many doctors that I came across knew this.


How is your sense of taste? Sensitive or no?

I use fragrance free soap and cedarwood scented body wash and deodorant. As long as you're clean you should be fine. It's not something you have to worry about if you practice basic hygiene.


Smell and taste are very intertwined. I wonder if your taste is very subdued as well. When I had covid, I couldn't smell anything, and eating a world class meal may have just as well been some cardboard...


People say this a lot, but I’m very skeptical whether it matters much if you never had smell to begin with. I have had no real sense of smell for as long as I can remember but I’m a more than competent cook. This would be very contradictory if smell was truly essential to the experience. I can believe that it’s important if you had it and lost it, but I don’t think smell is essential to taste in general. (However, I do agree with GP that it feels like I’m missing a major piece of human experience.)


As someone who has had the ability to smell go away and come back, I can confirm that smell is important for taste, but not the way it is often described.

For me, I can taste the “basic components” of flavor, but smell is necessary to add nuance/complexity.


> I don’t think smell is essential to taste in general

Depends on the ingredient. Some, like cinnamon, rely more on the sense of smell, while with others it doesn't matter much. In the end other senses always have some kind of effect on it, even if it's just the placebo kind.


I have no smell, but I do appreciate all kinds of foods and tastes.

Mostly the only thing I noticed that I lack are spices. I have no idea what these are for, so I just blindly follow the recipes, hoping not to mess it too badly.

That said, I never had it to begin with, so I may be missing on something I don't know...


Same experience. I normally enjoy food a lot, for a while there nothing tasted amazing. A sad experience. But even better when it came back.


I thought that too, but when I got Covid I lost my sense of smell for a few days, but could still taste things.


Since you don’t have a sense of smell, have you wondered if perhaps one of your other senses is enhanced in some way from using the spare brain matter? Do you have synesthesia?


Luckily most people can't tell if they smell (unless it's really bad). We typically rely on cues from those around us if were bathing right!


You have smell blindsight. Your subconscious can smell, but your aware part can not?


Got any references to this?

I never had any smell, but lately I have very short episodes when I was surprised to smell something, until it disappears again.

I didn't notice any specific pattern about when it happens either, it's just a couple of seconds sometimes.


I knew a pair of brothers with no sense of smell. Probably genetic for them.


Does your lack of smell extend to a lack of taste, as well?


No idea, how could I tell lol. My taste in food is, by others account, shite tho. I can eat the same things for days for all I care.


Get some (sugar free) rose water [0] and drink it. Compare with water. If they taste the same, you might be missing out on a lot of taste (but you will still be able to taste, say, salt vs. sweet).

More simply put though, if you definitely don't have a sense of smell, you most likely don't have a sense of taste either. I lost my sense of smell due to Covid for a bit, so I have some first-hand experience.

[0] https://www.amazon.com/Cortas-Rose-Water-1-Count/dp/B00V8TRZ...


Why rose water specifically? I can definitely differentiate sugary water vs pure water.


As the other commenters said, it's about testing your palate vs. your tongue. I made a mistake in my original comment where I said you don't have a sense of taste without smell, I meant to say you have only taste (sweet, sour, salty, bitter, umami) absent the flavors your olfactory equipment provides.


Because it's a suble difference especially if its sugar free. I think they're trying to test your ability to differentiate "perfumed" water vs regular. Sweetened or spiced things are more of a hammer.


Because rose water is subtle, not sugary.


One fascinating thing about Covid is that we discovered the loss of smell that it caused wasn't just due to Sars-CoV-2 wreaking havoc in the lungs, but that it got into the brain, and caused damage there.


Maybe it's related to the brain damage part: COVID didn't just kill my sense of taste and smell, but changed how I perceived touch too. Touch on my skin felt like I had a thin layer of something on my skin, even my teeth. It went away the same time I recovered my taste and smell. https://twitter.com/esesci/status/1608553863937921025?s=20

I didn't notice anything unusual about my hearing though.


For myself and several friends who started with poor senses of smell, covid boosted our sense of smell for a brief time after having it. My smell was easily 5x as sensitive for a month after having covid the first time. Now it's back to baseline.


I found that the lack of pollution at the beginning of lockdown increased air quality and my sense of smell became more noticeable and sensitive. Particularly in many walks around gardens and the countryside which was in spring. Or perhaps my perceptions of the smells increased rather than being able to smell more things.

Even three years later i've still a good smell sense. I love it.

It's possible that I had an early infection that triggered this response.


Yes I noticed the same, I had always thought that my hometown had very clean air (which by comparison it has) and that's why I never could smell pollution. After some staying at home during the pandemic, even the clean modern cars that passed every ten minutes or so on the calm suburb road REEKED of burning hydrocarbons. Going near the main road was terrible. Now again I can't smell the cars, the main road feels like clean fresh air (even though there are way more cars) maybe if a small motorbike drives by I can smell it


Interesting parallel with smoking ... I always had a pretty poor sense of smell, then smoked for a number of years, and for about two weeks after quitting I could smell everything. I didn't know office bathrooms were so bad...

And then similarly it went back to baseline.


This happens to me when I fast for a period or 3-5 days after becoming ill. For about a week after catching a stomach flu, the world smelled and tasted exactly as I remembered it being when I was a kid.


This isn't that surprising, is it? Influenza can do the same thing.


much more profound for covid usually https://www.bbc.com/news/health-53810610


Even so I’m not sure it’s common knowledge that influenza can do that.


No, it didn’t get into the brain and cause damage in the brain, it it affected the cells around the olfactory nerves.

https://www.forbes.com/sites/williamhaseltine/2022/02/14/los...



I didn’t say Covid does not get in the brain or affect the brain. I was saying that the olfactory issues are not caused by infection in the brain, but rather infecting the nasal passage directly.


[flagged]


Could you please stop posting unsubstantive comments and flamebait? You've unfortunately been doing it repeatedly. It's not what this site is for, and destroys what it is for.

If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site more to heart, we'd be grateful.


My father lost his sense of smell due to Covid and it never really came back entirely, he always complains that his food tastes nothing these days.


I sympathize, I lost my sense of smell and taste for two months, and almost two years later, coffee still tastes vastly different from what I remember.


I had phantosmia three times following COVID. Cigarette smoke each time. The first time lasted nearly a month and was very intense, with the subsequent instances lasting for shorter intervals and not being as intense. I was worried for a minute there that it was my new normal but I'm happy to report I haven't had any further instances in nearly 2 years. It was wretched.


Among the folks I know, the number who lost their sense of smell in their 30s-40s who later went on to develop some form of dementia is 100%, n=5.

Different countries, different cultures and backgrounds, but the common denominator is loss of smell predated their dementia diagnosis by ~20 years,+/-5.


My dad could not smell for a few years in his 50s - he has Parkinson's disease now, which started (noticeably) about 20 years later.

It seems to be subjectively quite awful (depression-like symptoms, difficulty walking - sports was a big part of his life) but at least I can still talk to him like an adult - it's not a proper dementia.


On a similar note, I recall this research[1] from some years ago about how loss of smell was a strong predictor of death within 5 years in older people.

[1]: https://journals.plos.org/plosone/article?id=10.1371/journal...


Unexplained and persistent hyposmia or anosmia is definitely correlated with dementia. Doctors do look for it in practice as it's often an early sign. Precise statistics escape me at the moment.


I've lost my smell and a lot of my taste thanks to covid, even after a couple of years it hasn't returned.

The strange thing - it started to come back in early February, very slightly, I could smell things I'd not been able to for a while - like cinnamon, or rose.

Tested positive for covid a few days later. Once covid tested clear using a lateral flow test my smell went.


That is fascinating that your sense of smell came back "due to covid" and then went away again. I'm suffering from long covid as well and the loss of probably 50% of my ability to smell. Taste went away at the same time as smell, but it quickly came back within a week. Not so with my sense of smell.


The unique relationship between nasal cavity and cranial cavity tissues in anatomy and physiology makes intranasal delivery to the brain feasible. An intranasal delivery provides some drugs with short channels to bypass the blood-brain barrier (BBB), especially for those with fairly low brain concentrations after a routine delivery, thus greatly enhancing the therapeutic effect on brain diseases.

https://pubmed.ncbi.nlm.nih.gov/18817519/

https://en.wikipedia.org/wiki/Olfactory_bulb

https://en.wikipedia.org/wiki/Olfactory_nerve

I have heard that the brain kind of sticks out into the sinuses, which may not be technically correct but the illustrations etc above show that there is a uniquely direct connection between the sinuses and brain via nerves that pass through very little tissue at a minimum.


The olfactory nerve extends directly from the brain. It is the first cranial nerve pair.

https://en.wikipedia.org/wiki/Cranial_nerves

The nerve forms a bulb directly above the nasal cavity. That bulb emits many smaller projections through the skull and into the nasal cavity.

https://en.wikipedia.org/wiki/Cribriform_plate

https://en.wikipedia.org/wiki/Olfactory_foramina

The nerves pass through those holes in the bone which are called olfactory foramina. Foramen means hole and these foramina connect the cranial cavity to the nasal cavity.

The paranasal sinuses are nearby structures. The olfactory nerves do not go in there.

It's absolutely a fact that the nose is pretty much directly connected to the brain though. The best demonstration of this fact is naegleriasis:

https://en.wikipedia.org/wiki/Naegleria_fowleri

https://en.wikipedia.org/wiki/Naegleriasis

This thing lives in water. If that water enters your nasal cavity, it will travel via olfactory nerve to your brain where it will proceed to literally eat it.


> the power of the nose peaks in middle age, around age 40

The more you know. But that also means I (< 40) shouldn't be too paranoid yet.


As someone who has suffered from microbiome issues for years, I'm confident they're looking in the wrong place. I'm sure there's changes happening in the brain, but my bet is it's actually starting in the intestines and caused by a bacteria or bacterial imbalance.

I've had a lot of things happen to me from lack of smell, heightened smell, tinnitus, sound sensitivity, memory issues, cognitive decline, changes in skin sensitivity, hair loss, etc. I'm confident all of this seems from my microbiome because the symptoms I'm experiencing shift every few months as I work on treating it and experience improvements and worsen.


What does the opposite of it mean?

Where you get extremely heightened sense of smell?

Because you know how covid made many people lose their sense of smell, many permanently?

It did the reverse to me, it made my sense of smell exponential. I've only read a couple stories of other people having this problem.

It's not a good thing. The world smells horrible. Way way before I can even hear the garbage truck I can smell it blocks away. Even if a street is empty early in the morning I can smell when someone has been there recently smoking cigarettes or other.

It's like some kind of fight or flight survival instinct or adaptation is triggered by the immune system.


That's fascinating. I remember reading a book where a woman said her grandmother (who was from a nomadic tribe in Africa) could smell rain from many kilometers away. Is this somewhat similar?

Are you living with this for how long? What does your doctor says?


Same effect here, and same bad conclusions about the world's smell. It's like a superpower, only detrimental.


That makes scents. :)

But yeah very very poor sense of smell with olfactory hallucinations and I got a bunch of T2 flares around my bilateral occipital horns so that sounds plausible.


I have this strange thing where I can smell better than most around me, but it's very faint and not very detailed. It almost feels like I have a really bad sense of smell, and yet I smell many things that others do not.


These days, loss of smell is most likely to be long Covid.


Beta Alanine has a propensity to depositing itself in the olfactory bulb, so do we see diseases or malnutrition?


Do you mean beta amyloid?


No not beta amyloid, but I could have also said carnosine instead of beta alanine, which is why I say, is it malnutrition?

"The only study available, which assessed carnosine in the brain of human cadavers, revealed little, if any, carnosine in brain regions other than olfactory bulb"

https://journals.plos.org/plosone/article?id=10.1371/journal...

"Effects of carnosine on olfactory bulb EEG, evoked potentials and DC potentials" https://pubmed.ncbi.nlm.nih.gov/6254611/

"Carnosine in primary afferents of the olfactory system: an autoradiographic and biochemical study"

"Previous in vivo studies have shown that beta-alanine is incorporated specifically into the dipeptide L-carnosine (beta-alanyl-L-histidine)."

https://pubmed.ncbi.nlm.nih.gov/6801217/


Didn’t this novel coronavirus bring on loss of smell in many people? Hmm


It's also a pretty common side effect of colds, flu's, and sinus infections. [1]

I never understood why loss of smell became such a focus with Covid, that symptom wasn't novel and I never found anything definitive studies finding it to be more common with Covid vs the others.

[1] https://www.yalemedicine.org/conditions/smell-and-taste-diso...


Complete anosmia with cold/flu/sinus infection is rare. Typically you can't smell anything because your nasal passages and olfactory bulb are fully occluded by excess mucus. The loss of smell is physical. If you blow your nose you can usually still smell a bit.

With COVID the loss of smell was fully neurological. It's like...a null vs. a 0. And it persisted in some cases, to the point that some Long COVID cases had to retrain their palates to fully taste food (e.g. overcoming aversion to alliums). That was the novelty.


It was not fully neurological in Covid. It affected the cells around the olfactory nerves. Nothing more.

https://www.forbes.com/sites/williamhaseltine/2022/02/14/los...


I don't think "nothing more" is the right conclusion here.

From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8658706/:

"Long COVID-19 anosmia fatigue could result from damage to olfactory sensory neurons, leading to an augmentation in the resistance to cerebrospinal fluid outflow by the cribriform plate, and further causing congestion of the glymphatic system with subsequent toxic build-up in the brain... SARS-CoV-2 can either travel via peripheral blood vessels causing endothelial dysfunction, triggering coagulation cascade and multiple organ dysfunction, or reach the systemic circulation and take a different route to the blood–brain barrier, damaging the blood–brain barrier and leading to neuroinflammation and neuronal excitotoxicity."


What kind of cell are olfactory receptors?


I completely lost my sense of smell in April from a regular cold. It is back now perhaps 25%.

The ENT says it does happen, and come back in 6 months to get a brain scan if it doesn’t.


Ask your ENT how often they saw that in their practice before COVID compared to after.

There's no symptom of COVID that can't be caused by a more common respiratory virus, but the frequency and severity of COVID symptoms is much higher.


Maybe my experience was different but the lack of smell from COVID was farrrrr more acute and noticeable than I’ve ever had with a sinus infection. It was like the sensation just starkly disappeared rather than diminished. It was really one of the most disconcerting symptoms I had if I’m honest!


There's a physical aspect as well as a mental aspect to it. Media is constantly feeding you information about loss of smell (even though I've lost it at least a few times before with viruses).


I am very much in the skeptical camp when it comes to many things with COVID, and open to all sorts of arguments that the nature of the virus and treatments for it do not adhere to what you might call the "orthodox" perspective presented on CNN and enforced by Facebook and Twitter moderators with comms degrees. That said, while the nocebo effect is definitely a thing, my own experience with my first infection was different enough from any other illnesses to this point that I'm convinced these symptoms and their severity were not just a matter of media hype. My first sign of COVID was major conjunctivitis in one eye, which for about an hour was associated with enough pressure I thought I might need to go to urgent care. Then, I had been completely recovered for about a week after I was infected, thought I was over it completely, and then noticed I couldn't smell the family dog and the only thing I was still able to taste was pickles. It should at least be possible to acknowledge the novelty of these symptoms without worrying that they make any sort of case for the propriety of the response or the encouragement of the public to treat SARS-CoV-2 like a virus from a zombie movie.


A friend of mine also lost his sense of smell for weeks, he also found that he absolutely hated the taste of hot coffee for months (cold brew didn't bother him)

My original one was simply that anecdotal accounts of loss of smell didn't seem to pan out to a significant difference in frequency compared to other common cold and flu's.


I could buy that maybe COVID had "some effect on smell" at about the same rate as the common viruses, but it was the intensity which made it more noticeable.


That's definitely possible, I was only talking about frequency. Intensity is a tricky one to track because it can only be based on self-report studies, and you only hav a frame of reference if a previous illness at least partially knocked out your sense of smell.


My ex's kids turned off the freezer in my garage while playing (turned a knob they didn't understand) causing all the food to spoil and I didn't smell it because I couldn't smell it. Turns out it was the media's misinformation in my garage all along.


Well my experience is that I have had colds and flus all my life and they never affected my smell or taste at all.

I got Covid once and lost 100% of my smell and taste for about 2 weeks.

I’m sure lots of other people must have shared this same experience.


I've actually had the opposite. I have lost my sense of taste for a couple weeks with previous illnesses. With what I'm pretty sure was Covid I had a killer headache on day one and a cough that lasted weeks, but never lost smell or taste.

I say I'm pretty sure it was Covid because the timing, exposure, and symptoms all lines up but I never actually got a positive test result from at home tests.


I lost 50% of my smell from covid. Not that I could smell things at half strength, no. I got out all my spices and smelled each one. Lemon pepper, yes, Cumin, no, oregano yes, cloves no, and so on. I could smell half the spices just fine and the other half not at all. I've never experienced anything like it in my life.


That's a really interesting one for sure, though still it's anecdotal and I at least haven't been able to find a solid study showing a higher frequency of loss of smell symptoms with Covid.


Someone I know lost the ability to sense many organosulfur compounds after having Covid. Garlic is tasteless/smell-less mass, rotten eggs don't smell like anything. I don't think I've ever heard of sinus infections of any kind causing that kind of change for going on 3 years. That's pretty weird considering how sensitive humans are to organosulfur compounds.


paired with diminished taste and continued mentions of potential chronic ongoing fatigue and mental fog, it probably got mentally weighted higher as something to be defensive toward

it's a pretty primal human fear to be stripped one by one of your senses, considering it's not as common in other cases of illness VS the sudden worldwide common repeated exposure to covid when in some public places, added on with some general anxiety from covid it's not entirely hard to understand others viewpoints being emotionally skewed


It became a focus because it was happening to millions of people across the world very abruptly?


I have in the past lost my sense of smell due to polyps in my sinuses that were caused by allergies. Removal of the polyps fully restored my sense of smell (even made it better than before)


I’ve had colds and flus plenty of times, and yeah, you somewhat lose your sense of smell when your nose is clogged up.

The loss of smell and taste when I had covid was nothing like that.


A fact-focused comment with receipts, greeted with downvotes.


It is worth pointing out there are other reasons for loss of smell sensitivity. A lifetime of steroid sprays for hayfever, allergy and rhinitis.

So "OMG I can't smell it must be dementia" needs to be modulated through "yea: have you had a lifetime of squirting stuff up your nose"

Hence (and other reasons, but this would be one) the MAY in the title.


Is there a good source I can read about this?




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