By using mass spectrometry, a technique that measures the weight of molecules, they have found that there are distinctive Parkinson’s markers in sebum – an oily substance secreted from the skin.
This breakthrough has led them to develop a non-invasive swab test that can, in conjunction with the onset of early Parkinson’s symptoms, identify Parkinson’s disease with around a 95% accuracy. What’s even more astounding is the speed with which the test can return a result; around 3 minutes under lab conditions.
https://www.manchester.ac.uk/discover/news/a-nose-to-diagnos...
I was reading along and thinking to myself "why aren't we taking these tee-shirts to a mass spectrometer?!" I figured maybe mass spectroscopy wasn't quite the end all be all tool I was imagining.
Since she could also smell TB, Alzheimer's, cancer, and diabetes it seems like those should be (especially cancer since dogs can smell some of that too) the next high value targets to determine the relevant smells.
The story for diagnosing Parkinson’s sounded plausible until this sentence. With Parkinson’s, you could imagine that she had some sort of sensitivity in her smell to a certain biomarker.
Now with a plethora of vastly different diseases (even cancer is really a myriad of diseases grouped together), the suspicion of a confounder goes way up.
Perhaps instead of diagnosing Parkinson’s, she is actually sensing some signal that indicates inflammation or some other distress signal.
Or else people, prior to the manifestations of these diseases tend to make subtle, unconscious changes to their hygiene.
It sounds like you are assuming that every one of those illneses smell the same to her. That is that she can tell that someone has Parkinson’s or tuberculosis, or Alzheimer's, or cancer or diabetes, but she can’t tell which one they have.
The way i read it is that she can identify which one people have based on how they smell. Totaly made up example: tuberculosis smells peppery, while Alzheimer minty, and so on and so on. (Admittedly this also assumes that the journalist was sloppy about cancer. Probably she was only tested on specific types of cancers. It is very unlikely that all cancers would smell the same. But this is something which is very easy to get jumbled up by the journalist.)
Ultimately it doesn’t matter. If it verifies through a properly designed test protocol they will publish a paper about it. If not, they won’t. So if it matters we will hear about it.
In the end, all this should not be so difficult. Take the head space, then do MS of a bunch of people with these diseases and the head space and MS of healthy people as a comparison. The delta gives the disease.
Not to discount the woman or the article, we should totally be researching this stuff
And I wouldn't be surprised if things like "cancer" were actually a confounder (I'm thinking along the lines of detecting the body's reaction rather than the tumor itself)--but it's still useful information. They've already used her information to find a albeit imperfect test for Parkinsons. What if you had a similar test for cancer? It would tell the doctor to start looking in fashions they would not do for the general population.
If no one in a normal state has the same mix of fear, anger and confusion and this leads to a microbial change around sweat glands, then that is a valid test of greater accuracy than many existing medical tests.
Impressive in itself, but that's useless for diagnosing people who don't know they have a disease, which would be the medical breakthrough.
The issue is the one of the false positive and bayesian statistics. If she's detecting something that has a bunch of common causes then it's not really helpful to run a suite of tests to find an underlying problem on everyone that smells the same.
A fever can be a sign of cancer, but it's also a sign of the flu. Should we check everyone with a fever for cancer?
Smelling tuberculosis seems plausible to me, it is a disease of the lungs.
General cancer probably no, but I have repeatedly read comments by oncologists that sarcoma, specifically, has a distinct smell.
How do people even get a handle on what a smell is, and how personal an experience is it.
The Alabama paper is open access and well worth reading if you’re interested in Parkinson’s
https://www.uab.edu/news/research/item/13280-new-study-puts-...
I've always wondered why my grandfather smelled a certain way. Your comment made me realise that this was probably a side effect of Parkinsons.
It took me until my 30s to discover other people didn't know/realise/detect this. But since I've shared it with people as an interesting party trick type thing I've found many people who could smell onset of a cold.
It's not surprising to me that people can smell so much more, as all of our senses differ from person to person, the range, intensity, sensitivity.
What does surprise me is turning that into a useful application that could be used by others without the same sensory capabilities, that's neat.
You're probably not sniffing random people to chat them up with "you'll have a cold in 3 days", right?
I have got into the habit of telling people close to me, and it gives them a chance not to avoid getting a cold, but to mitigate the impact by treating the symptoms before they've really emerged.
https://www.science.org/content/article/widely-used-chemical...
https://www.medrxiv.org/content/10.1101/2023.11.01.23296924v....
I wouldn't assume anything. And it might not be related to sensitivity in general, but sensitivity to a particular chemical. (Also, is the perception of smell tied only to sensory aparatus in the nose?)
> finding others with it is a bit of a chicken-and-egg problem: how do you efficiently screen for this without knowing the precise compounds are to be targeted?
Expose them to people with Parkinson's; based on her experience, it seems like a quick test. In her case, they tested it with t-shirts worn by people with Parkinson's.
A Woman Who Can Smell Parkinson's - https://news.ycombinator.com/item?id=21532937 - Nov 2019 (87 comments)
A woman who can smell Parkinson's disease - https://news.ycombinator.com/item?id=10434974 - Oct 2015 (114 comments)
Edit: might be related to all (or some) those different esters in sustanon
The temptation to use it as a curse would be too great.
You spilled water on my shoe! sniff I curse your grandfather with dementia!
And when grandad got dementia they would think of me and hate me and wonder if evil magic was real.
Jesus, laugh a little.
I did, but then I got worried about humanity.
I guess, a nice impact of this story is that people with Parkinson's are gonna see it and ask their friends, "do I have a smell?" If she's not rare, we'll find out.
They also found the molecule she was smelling which was expressed with sebum. This isn't entirely unfounded as they already knew about dogs smelling cancers and other various diseases.
Again, I'm not an expert, but from personal experience I know that Parkinson's can be hard to diagnose definitively until there are serious symptoms. This test may be relatively poor but still be useful as a piece of evidence.
[1]: https://www.sciencedirect.com/science/article/abs/pii/S03038...
[2]: https://pubs.acs.org/doi/full/10.1021/acscentsci.8b00879
But here's the problem as I see it. Parkinsons has an occurrence rate in the population of 0.1%. If there are conditions which cause the same smells as Parkinsons and they are more common in the population (1%, 5%, 10%) then this test all the sudden becomes very not useful because even at 1% occurrence rate in the population it's already 10x more likely that you have that condition rather than Parkinsons. That's the confounding problem. And a different comment here pointed out there are conditions that also seem to have exhibited the same smells.
Who knows, perhaps this is still worth it, but for an n=30 study, this is basically nothing to consider. The group size is simply way too small.
BTW, Medical media reporters really should have a "No reporting on studies with n < 500" rule. These sensational studies are always preliminary on really low population groups. I'd love to see the meta analysis to know how many studies it's lumped in and how big those are, though.
Absolutely, it may not be useful as a screening test on the general population, but it may be useful as a piece of evidence for diagnosis alongside other pieces of evidence. Even for a test with a lot of false positives, the P(Parkinson's|positive) > P(Parkinson's|negative).
I generally agree that a lot of media doesn't accurately portray uncertainty in medical advancements, buts it's not as simple as having a sample size threshold. It really depends on the significance and the strength of the effect. Also, I want to hear about the exciting preliminary stuff, provided that it's properly caveated. There's just a lot of incentives to sensationalise.
- https://www.theatlantic.com/science/archive/2015/11/the-voca... - https://www.wired.com/2014/11/whats-up-with-that-smells-lang...
There's a whole pyramid scheme for perfumery, of course.
In general in the vocabulary of smells you try first to understand the instrument (certain fruit, manure, sea, etc) and then the intensity of it.
I'm not very familiar how the intensity and variations are described but I presume that it is not as formal as in the case of music.
But it has no help if you can't smell it (the frequency is out of the hearing limit) or you can't recognize the instrument from the noise.
Is there anything they can do about the breath? (ditto people on keto diet)
[0] https://www.webmd.com/diabetes/acetone-breath-diabetes
So low blood sugar causes sweet breath.
What are "larger, more complex, molecules"? Without trolling, I think scent cuts off at a MW 330 or something.
It's basically a dynamic range problem.