12 ms·

A woman who can smell Parkinson's disease

251 points by dan1234 11y ago

2skep 11y ago
I bet they didn't randomise for brand of deodorant and diet which makes this research almost meaningless.
- knodi123 11y ago
  it was a sample of 12 people, so it's already meaningless. this "research" is the justification for a study, not a study in and of itself.
  - sliverstorm 11y ago
    How is it simultaneously meaningless and also a justification for further study?
    - opnitro 11y ago
      Meaningless to draw large scale conclusions on. It's a "This is something we should look more closely at" not a "Send this person around the country STAT"
  - biomcgary 11y ago
    What makes this result meaningless? The probability of her guessing all 12 correctly at random is: 0.0002 (i.e., approximately 0.5^12). So, it is far more statistically significant than many published results.
  - Rexxar 11y ago
    The minimal sample size depends on the effect you try to measure. Big effects can be validated with smaller sample size.
  - KingMob 11y ago
    While it's true this is mostly justification for further investigation, correctly categorizing 12/12 people into 2 categories actually has a p-val of .000244141 = (1/(2^12)), which would easily allow you to reject the null hypothesis of random categorization. The stronger the effect, the fewer samples you need. We consider n=12 generally underpowered only because many real-world effects are way weaker than the ability this woman demonstrated.
- scott_karana 11y ago
  Well, if diet or deodorant causes Parkinson's, that's absolutely meaningful. ;) The methodology should have been mentioned more in the article, and should be scrutinized, but that doesn't mean it's worthless if she truly diagnosed these people after a (single?) blind experiment.
  - ars 11y ago
    > Well, if diet or deodorant causes Parkinson's, that's absolutely meaningful. ;) You jest, but there is actually a suggestion that aluminum in sweat blocking deodorant causes neurological problems like Parkinson's and Alzheimer's. (The evidence for this is not strong however.)
    - cortesoft 11y ago
      This wouldn't explain why she noticed a change in her husband's scent. I would assume he was using the same deodorant before and after the change.
      - 2skep 11y ago
        one, that assumption is not tested. two, it is also not tested that the smell she say she noticed had anything to do with parkinson's. I know someone who can predict the future by looking at tea leaves.
- azernik 11y ago
  Do you have any reason to think brand of deodorant and diet are strongly correlated with Parkinson's? (Especially pre-diagnosis.) Ideal would be to check large numbers of undiagnosed people, and then see how many of those she "alerted" on developed the disease, but given the generally-low incidence of Parkinson's I suspect this approach would be impractical. Larger sample sizes than 12 would always be nice, of course.
  - spacehome 11y ago
    Are you kidding? That'd be awesome if we could skip these expensive tests and diagnose Parkinson's by deodorant brand preference!
  - 2skep 11y ago
    No, if we discovered that all 6 (+1) happen to use the same deodorant which have the smell she thinks is parkinson's it would make the research look a bit silly.
- mfoy_ 11y ago
  I can't tell if you're being sarcastic or not... But the "research" is literally just concluding "Hey, there may be a simple way to test for this incredibly hard-to-diagnose disease".
- klodolph 11y ago
  But in the real world, we do less rigorous studies first and follow up with more rigorous studies if our preliminary investigations show promise.
  - mikekchar 11y ago
    I always wonder if this is a good idea. While getting a false positive is not really a problem, because you're going to do a follow up experiment, what happens to the things we miss? If you do an experiment that doesn't really have a large enough sample size, or comes from a biased sample (because it's really an offshoot of a different experiment) and you decided that there is no effect, does it stop others from researching that effect? I suppose since we don't tend to publish negative results maybe it doesn't matter, but it's always something that has niggled at me.
    - KingMob 11y ago
      The trade-off between Type I and Type II error is an inherent problem in research. But false positives are most certainly a problem, too. Just look at the issues psychology and biomedicine have been grappling with in terms of replication. Whole careers were wasted based on what seem now like false positives.
- Pyxl101 11y ago
  Please avoid gratuitous negativity on Hacker News. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
Mz 11y ago
"Her accuracy was 11 out of 12. We were quite impressed." Dr Kunath adds: "She got the six Parkinson's but then she was adamant one of the 'control' subjects had Parkinson's. "But he was in our control group so he didn't have Parkinson's. "According to him and according to us as well he didn't have Parkinson's. "But eight months later he informed me that he had been diagnosed with Parkinson's. "So Joy wasn't correct for 11 out of 12, she was actually 12 out of 12 correct at that time. "That really impressed us and we had to dig further into this phenomenon." Reminds me of the story I heard about a doctor who was diagnosing an STD a lot earlier than average. They put two other doctors in the room with him to try to spot what he was seeing and identified the eye flutter as a new symptom, I think for syphilis.
codeonfire 11y ago
I'm too lazy to do the math, but I'm just going to say a test like this needs more than a sample size of 12 to show significance for detecting something that happens 1 in 500. The woman also was predisposed to thinking that at least some of the 12 had Parkinson's and the sample selection ensured that at least half did have Parkinson's. An actual test would need to allow any possible sample including those that had zero Parkinson's patients.
- comex 11y ago
  Well, to be conservative, assume she was told or guessed that 7 out of the 12 samples were from patients with Parkinson's, which more than accounts for the "predisposed to thinking at least some" factor - actually it would make more sense to guess six, but that can only make the correct response less likely. Twelve choose seven is 792, so out of the 792 possible responses, she chose the single exactly correct one. No fancy statistics needed - the p-value (defined, according to Wikipedia, as the probability of obtaining an equal or more extreme result, the latter of which doesn't apply as the result is already the most extreme possible for the experiment) is simply 1/792 or about 0.001 (0.1%).
  - codeonfire 11y ago
    That's ridiculous. That's like saying someone who wins the lottery is clairvoyant with P=0.00. I mean they got the exact right numbers which had 1 in 147 million chance, right?
    - exgrv 11y ago
      A lot of people play the lottery. Only one person did this experiment. When you test multiple hypothesis (as in your lottery example), you need to perform a correction[2,3]. [1] https://xkcd.com/882/ https://xkcd.com/882/ [2] https://en.wikipedia.org/wiki/Multiple_comparisons_problem https://en.wikipedia.org/wiki/Multiple_comparisons_problem [3] https://en.wikipedia.org/wiki/Bonferroni_correction https://en.wikipedia.org/wiki/Bonferroni_correction
    - swsieber 11y ago
consta 11y ago
Impressive but I don't see the point of diagnosing Parkinsons in early stages when there is no cure available.
- ars 11y ago
  How do you know there is no cure for early diagnosis? Until today it wasn't possible to diagnose early.
- ajkjk 11y ago
  Fortunately, everybody else does. Why would we not want to be able to discern life-threatening information sooner? Not to mention the value in correlating another physiological change with the disease. Maybe research into how this works can get us closer to a cure.
  - Alex3917 11y ago
    > Why would we not want to be able to discern life-threatening information sooner? Because there's a good chance you'll receive a treatment that will cause you to die sooner than had you not known about the disease for another decade. C.f. why they pushed back the recommended age for mammograms this week.
    - lightyrs 11y ago
      That is a great point. Treatment is often the nail in the coffin; Sepsis, for example.
    - ajkjk 11y ago
      That sounds like a problem with the treatment, not a reason to remain ignorant about your own health for longer.
- IkmoIkmo 11y ago
  Well a few quick thoughts against that: 1) Wouldn't you want to know say a year in advance, before you made all kinds of hospital visits and it was finally confirmed? I bet you would. Perhaps to start preparing for a different life, career, perhaps to advance future plans of things you'll gradually become less able to do. People want to know. 2) Can you imagine that if somehow, for example, you could detect Parkinson's by smell, that this would open up all kinds of findings, research and understanding about what Parkinson's is, how it works, how it's detected etc, that could potentially lead to better treatment or even a cure? I bet you can imagine there's a positive correlation between understanding something better and the ability to treat it in future. 3) it's simply interesting in and of itself. How curious, isn't it?
klodolph 11y ago
There are a couple people picking on this research in the thread. This is a preliminary study, just a "bullshit test" to see if this woman is crazy or if she's not. It's obvious that she's not crazy, because all she's doing is sniffing t-shirts and she doesn't know who they belong to. The sample size is large enough, we have a p-value of no more than p=0.0012, and that's under the cynical assumption that she somehow knew that exactly seven of the twelve samples would have Parkinson's... something that the scientists didn't know. So we know that something is going on here. The next steps are to control potential confounding variables and to determine the sensitivity and specificity of the test, if it's shown that she's not actually detecting some confounding variable. This is where you go double-blind, you use larger sample sizes, et cetera, now that you have money. You have money because the preliminary research was promising. And we're not just getting a good test out of this. If there's an actual chemical that she's smelling, then there's some chemical process that's going on in people with Parkinson's which isn't happening in people without Parkinson's (or vice versa). Tracing these chemical pathways could give us clues to the etiology of the disease, which would be a REALLY BIG DEAL. Or maybe it's just a rabbit hole.
- cbd1984 11y ago
  One of the great things about science is that we can determine whether a phenomenon is likely real without having to have the slightest clue what the mechanism might be. Evidence comes first, and this looks like solid evidence, and mechanism can come later; the evidence alone proves the existence of something interesting, and that's what's worth a follow-up. Hypothesis generation is important, because it helps us design the next experiment, but this experiment is already very interesting.
  - nnethercote 11y ago
    > One of the great things about science is that we can determine whether a phenomenon is likely real without having to have the slightest clue what the mechanism might be. You just have to ignore the people who shout "correlation is not causation" at every opportunity, appropriate or not.
seccess 11y ago
My grandpa died of parkinson's, its a really slow and heartbreaking disorder. I think early diagnosis would be wonderful. It runs in the family, and his two older brothers and father had it, so he lived a very preventative lifestyle - especially with respect to daily exercise. I think it paid off, he lived to 85 while both his brothers died 20 years younger.
jarmitage 11y ago
Reminds me of this anecdote from Fishing with John: "I heard a story about this woman that was swimming in the ocean, and dolphins started swimming with her, and the dolphins kept poking her in the chest above her breast. She got scared and they took her out of the water, and she had a big bruise right on the top of her breast. They took her to the doctor to examine her, and they did a mammogram, and found that she had cancer right in that spot." – Jim Jarmusch, 'Fishing with John' https://youtu.be/uVa8rj1mm7A?t=912 https://youtu.be/uVa8rj1mm7A?t=912
- lost_my_pwd 11y ago
  Not sure if it is scientifically confirmed but it is believed that dolphins can see inside a body to some extent with their sonar abilities.
  - jarmitage 11y ago
    Wow, link for that?
    - dewarrn1 11y ago
      I can't vouch for dolphin sonar resolving fine anatomical detail /in vivo/, but dolphins can recognize visually obscured objects using the ability [0]. [0] http://www.dolphin-institute.org/our_research/dolphin_research/seeingthroughsound.htm http://www.dolphin-institute.org/our_research/dolphin_resear...
    - tim333 11y ago
      There's a link with some stuff here http://www.livescience.com/38087-can-dolphins-detect-pregnant-women.html http://www.livescience.com/38087-can-dolphins-detect-pregnan...
- harvestmoon 11y ago
  Yes, and as the wise narrator of this parody series points out, "What is most remarkable about this story is not that the dolphin knew the woman was sick, but that it knew she didn't know already."
tcdent 11y ago
Interesting given the recent link between Parkinsons/Alzheimers and fungal infections: https://news.ycombinator.com/item?id=10401344 https://news.ycombinator.com/item?id=10401344
- ksml 11y ago
  I would not call that a definitive "recent link"; as many in that thread pointed out, that was not the greatest research and needs far more work to confirm
  - tim333 11y ago
    Yeah, more research needed. I also came across another 2013 "Fungus may cause symptoms of Parkinson's disease" article I found interesting. They "found that a compound emitted by mold, called 1-octen-3-ol but more commonly known as mushroom alcohol" "attacked two genes involved in the creation of dopamine" And speculate I think that could be related to the drop of in dopamine production in Parkinsons. It would be interesting to try some such "volatile organic compounds emitted by fungi" with the lady who can smell Parkinson's to see it the smell was similar. http://www.medicalnewstoday.com/articles/268848.php http://www.medicalnewstoday.com/articles/268848.php Also a 1990 article suggesting it's "the fungus, called Nocardia asteroides." I guess nothing much happening since 1990 suggests that didn't work out. http://articles.latimes.com/1990-05-17/news/mn-286_1_nocardia-infection http://articles.latimes.com/1990-05-17/news/mn-286_1_nocardi...
conductor 11y ago
Can anybody tell us what is the current state of the art in "electronic nose" sensors technology? Could they potentially be used to identify this smell?
- TeMPOraL 11y ago
  We're pretty good at detecting low concentrations of chemicals in the air if we know exactly which ones to detect. This case suggests there might be some previously unnoticed substances in the air that are indicative of one's Parkinson. If so, we'll probably quickly build dedicated sensors. The thing that makes me wonder though - what's the state of broad-range chemical sensing? Could a chemical like this be found before if we kept taking broad "smell" samples of everyone and cross-correlating them?
JulianMorrison 11y ago
Seems like they are going the long way about it to determine a molecule for a test. Why not just train a dog to smell it?
- jmiwhite 11y ago
  Smell what? It seems that _how_ this works is still unclear, if it works at all. Once validated, it seems plausible that a device/trained animal could replicate the results, assuming its not like this guy: https://en.wikipedia.org/wiki/James_Harrison_(blood_donor) https://en.wikipedia.org/wiki/James_Harrison_(blood_donor)
- KingMob 11y ago
  Well, since it seems likely there's now a scent-based marker, we could train dogs to sniff Alzheimer's out, but we'd still want to know more about the molecule and biochemistry for treatment purposes.
- deleted 11y ago
  [deleted]
IkmoIkmo 11y ago
The thing that most surprised me were the odds that a person in the control group (no parkinson's), actually did have parkinson's (diagnosed early according to the woman) and was diagnosed later to indeed have parkinson's. After all, the prevalence is 0.3% in the general population. The odds at least one of the six in the control group had parkinson's is around 2% (even less considering it's already a filtered audience in a way). Not impossible but very unlikely, which incidentally makes her insistence of that single particular person to have PD all the more interesting. There's definitely something there, looking forward to more testing.
- eterm 11y ago
  I don't understand the phrasing there, "She was adamant". If it was a controlled test, why should she need to be "adamant" about anything, surely she would have merely identified it.
  - MLR 11y ago
    She was adamant that one of the control group members (i.e. no Parkinson's) had Parkinson's.
  - deleted 11y ago
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  - IkmoIkmo 11y ago
    I guess after the test they told her the results (i.e., you're wrong on 1 person because he's in the control group and doesn't have Parkinson's), at which point she insisted that he smelled the same as the others, and then the journalist wrote that up as 'she was adamant he had Parkinson's'. Or she really did fully believe in her sense of smell as an ability to detect Parkinson's without doubt, at which point it as much sense for her to say a person has Parkinson's as you to say the sky is really blue because your eyes tell you and the journalist simply relayed that. There's various readings of the phrase that can make sense.
cafebeen 11y ago
Looking forward to hearing more--reminds me of work done to detect cancer by scent with help from dogs: https://en.wikipedia.org/wiki/Canine_cancer_detection https://en.wikipedia.org/wiki/Canine_cancer_detection
tomcam 11y ago
Galen relied on sense of smell for diagnosing illnesses. Aristotle wrote about it. Until the late 20th century doctors often used smell for diagnostics.
Mz 11y ago
This also reminds me of the breathe test being developed to check ammonia levels for certain kinds of patients: https://news.ycombinator.com/item?id=10402816 https://news.ycombinator.com/item?id=10402816
andy_ppp 11y ago
Some more truly fascinating Parkinson's news this week about nilotinib, apparently seeming to cure Parkinson in small trials... http://www.independent.co.uk/life-style/health-and-families/health-news/parkinsons-patients-given-new-lease-of-life-after-receiving-cancer-drug-in-trial-a6699031.html http://www.independent.co.uk/life-style/health-and-families/...
- tim333 11y ago
  Thanks for the link. There is another article in the New Scientist with more information https://www.newscientist.com/article/dn28357-people-with-parkinsons-walk-again-after-promising-drug-trial https://www.newscientist.com/article/dn28357-people-with-par... I'm on the look out for stuff for my dad who seems to have it. The data in the New Scientist article looks promising - all 12 of the patients started to improve, some dramatically and as to side effects the "team saw no unwanted effects".
bazillion 11y ago
This reminds me of when I was in the Navy -- at one point I had lived with hundreds of other guys in a ship's berthing and at another duty station I mentioned to a coworker that I could determine someone's race from their sweat. Of course, they called bullshit on that statement (as I'd imagine most on here would) and we tested it out with 4 guys (1 black[1], 2 white[2], 1 hispanic[3]) who sweated into the same size shirts, and I was able to identify them with 100% accuracy. Another time, I walked into a cubicle, wrinkled my nose, and said "Man! It smells like an old deck of cards in here!". One of the guys standing next to me then pulled out a rather well-played-through deck of cards out of his pocket. One of the reasons people give for the difference in smell are the difference in foods that different cultures eat. I definitely know this is not the case, as everyone on that ship was eating the exact same food, and their smells were extremely distinct. I understand that lack of science applied to my specific anecdotes, but I think there's something to be said for having a keen sense of smell, since people are already geared towards smelling other people's sweat to determine immunocompatibility[4]. [1] A black person's sweat is the one I can identify with absolute certainty, as it's completely unmistakable for anything else [2] A white person's sweat smells like a distinct type of onion to me [3] I couldn't really identify his race if it were just this shirt, but had that one by process of elimination. [4] https://en.wikipedia.org/wiki/Major_histocompatibility_complex_and_sexual_selection#MHC-mediated_mate_choice:_case_studies https://en.wikipedia.org/wiki/Major_histocompatibility_compl...
- gohrt 11y ago
  Different races definitely smell different; it shouldn't be surprise that a sweaty shirt contains that smell.
- JoeAltmaier 11y ago
  I hear anecdotally that Japanese think Americans smell like butter.
  - lovemenot 11y ago
    It is frowned on now, but in former decades some uncouth Japanese would say "Cheezu nioi" (smells like cheese) when encountering a foreigner.
firebones 11y ago
It would seem there are some major confounding factors here not detailed in the article. 1) The population doesn't reflect a realistic test--if the overall incidence is 0.3%, but the sample size had 50% (or more given her adamant hit), then we need to know whether she was expecting more. 2) More importantly, the incidence in men is 1.49x that of women [1], and age also plays a factor. So given that the sample is already skewed towards a higher incidence of positives, the gender differences might be factored into her senses--especially since it was her husband who was her training set. With n=12, it would be very easy for the probabilities/priors to be much different than truly random. (E.g., the learning function of her nose might be "men + people over 65" which happened to match up with the test and control group quite well.") Or it could tune into medication used to treat the disease. Great if true, but I am skeptical. [1] http://jnnp.bmj.com/content/75/4/637.full http://jnnp.bmj.com/content/75/4/637.full
- KingMob 11y ago
  If you look at the Bayesian analyses and the frequentist analyses assuming she knew how many AD shirts there would be, you'd see that point 1 doesn't matter. We can statistically test this without the need to make her sniff 1000's of shirts. Point 2 is interesting though, and the first thoughtful criticism I've seen in the thread. What if she's both a bit lucky, and also picking up on some correlated marker like age/gender?
Optimist45 11y ago
I know the odor she is talking about. My husband was diagnosed in January. His previous truck and his current vehicle have developed a very distinct odor. I used to say old musty Portuguese man but I realize it is the smell she is talking about. My husband has only used deodorant for 27+ years. This came about because anti-perspirant made his entire armpit swell with bright red welts. He also does not sweat much. It is a very sad disease, but will continue to search for ways to make it easier.
nyc111 11y ago
The question they did not ask what makes the body smell. When we eat garlic we smell like garlic. So the smell must be related to how the food is digested. The researchers should look at the gut flora, in other words they should do a study similar to this https://news.ycombinator.com/item?id=10439129 https://news.ycombinator.com/item?id=10439129 All disease start in the gut.

251 points by dan1234 11y ago

2skep 11y ago

I bet they didn't randomise for brand of deodorant and diet which makes this research almost meaningless.

knodi123 11y ago
it was a sample of 12 people, so it's already meaningless. this "research" is the justification for a study, not a study in and of itself.
- sliverstorm 11y ago
  How is it simultaneously meaningless and also a justification for further study?
  - opnitro 11y ago
    Meaningless to draw large scale conclusions on. It's a "This is something we should look more closely at" not a "Send this person around the country STAT"
- biomcgary 11y ago
  What makes this result meaningless? The probability of her guessing all 12 correctly at random is: 0.0002 (i.e., approximately 0.5^12). So, it is far more statistically significant than many published results.
- Rexxar 11y ago
  The minimal sample size depends on the effect you try to measure. Big effects can be validated with smaller sample size.
- KingMob 11y ago
  While it's true this is mostly justification for further investigation, correctly categorizing 12/12 people into 2 categories actually has a p-val of .000244141 = (1/(2^12)), which would easily allow you to reject the null hypothesis of random categorization. The stronger the effect, the fewer samples you need. We consider n=12 generally underpowered only because many real-world effects are way weaker than the ability this woman demonstrated.
scott_karana 11y ago
Well, if diet or deodorant causes Parkinson's, that's absolutely meaningful. ;) The methodology should have been mentioned more in the article, and should be scrutinized, but that doesn't mean it's worthless if she truly diagnosed these people after a (single?) blind experiment.
- ars 11y ago
  > Well, if diet or deodorant causes Parkinson's, that's absolutely meaningful. ;) You jest, but there is actually a suggestion that aluminum in sweat blocking deodorant causes neurological problems like Parkinson's and Alzheimer's. (The evidence for this is not strong however.)
  - cortesoft 11y ago
    This wouldn't explain why she noticed a change in her husband's scent. I would assume he was using the same deodorant before and after the change.
    - 2skep 11y ago
      one, that assumption is not tested. two, it is also not tested that the smell she say she noticed had anything to do with parkinson's. I know someone who can predict the future by looking at tea leaves.
azernik 11y ago
Do you have any reason to think brand of deodorant and diet are strongly correlated with Parkinson's? (Especially pre-diagnosis.) Ideal would be to check large numbers of undiagnosed people, and then see how many of those she "alerted" on developed the disease, but given the generally-low incidence of Parkinson's I suspect this approach would be impractical. Larger sample sizes than 12 would always be nice, of course.
- spacehome 11y ago
  Are you kidding? That'd be awesome if we could skip these expensive tests and diagnose Parkinson's by deodorant brand preference!
- 2skep 11y ago
  No, if we discovered that all 6 (+1) happen to use the same deodorant which have the smell she thinks is parkinson's it would make the research look a bit silly.
mfoy_ 11y ago
I can't tell if you're being sarcastic or not... But the "research" is literally just concluding "Hey, there may be a simple way to test for this incredibly hard-to-diagnose disease".
klodolph 11y ago
But in the real world, we do less rigorous studies first and follow up with more rigorous studies if our preliminary investigations show promise.
- mikekchar 11y ago
  I always wonder if this is a good idea. While getting a false positive is not really a problem, because you're going to do a follow up experiment, what happens to the things we miss? If you do an experiment that doesn't really have a large enough sample size, or comes from a biased sample (because it's really an offshoot of a different experiment) and you decided that there is no effect, does it stop others from researching that effect? I suppose since we don't tend to publish negative results maybe it doesn't matter, but it's always something that has niggled at me.
  - KingMob 11y ago
    The trade-off between Type I and Type II error is an inherent problem in research. But false positives are most certainly a problem, too. Just look at the issues psychology and biomedicine have been grappling with in terms of replication. Whole careers were wasted based on what seem now like false positives.
Pyxl101 11y ago
Please avoid gratuitous negativity on Hacker News. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

Mz 11y ago

"Her accuracy was 11 out of 12. We were quite impressed." Dr Kunath adds: "She got the six Parkinson's but then she was adamant one of the 'control' subjects had Parkinson's. "But he was in our control group so he didn't have Parkinson's. "According to him and according to us as well he didn't have Parkinson's. "But eight months later he informed me that he had been diagnosed with Parkinson's. "So Joy wasn't correct for 11 out of 12, she was actually 12 out of 12 correct at that time. "That really impressed us and we had to dig further into this phenomenon." Reminds me of the story I heard about a doctor who was diagnosing an STD a lot earlier than average. They put two other doctors in the room with him to try to spot what he was seeing and identified the eye flutter as a new symptom, I think for syphilis.

codeonfire 11y ago

I'm too lazy to do the math, but I'm just going to say a test like this needs more than a sample size of 12 to show significance for detecting something that happens 1 in 500. The woman also was predisposed to thinking that at least some of the 12 had Parkinson's and the sample selection ensured that at least half did have Parkinson's. An actual test would need to allow any possible sample including those that had zero Parkinson's patients.

comex 11y ago
Well, to be conservative, assume she was told or guessed that 7 out of the 12 samples were from patients with Parkinson's, which more than accounts for the "predisposed to thinking at least some" factor - actually it would make more sense to guess six, but that can only make the correct response less likely. Twelve choose seven is 792, so out of the 792 possible responses, she chose the single exactly correct one. No fancy statistics needed - the p-value (defined, according to Wikipedia, as the probability of obtaining an equal or more extreme result, the latter of which doesn't apply as the result is already the most extreme possible for the experiment) is simply 1/792 or about 0.001 (0.1%).
- codeonfire 11y ago
  That's ridiculous. That's like saying someone who wins the lottery is clairvoyant with P=0.00. I mean they got the exact right numbers which had 1 in 147 million chance, right?
  - exgrv 11y ago
    A lot of people play the lottery. Only one person did this experiment. When you test multiple hypothesis (as in your lottery example), you need to perform a correction[2,3]. [1] https://xkcd.com/882/ https://xkcd.com/882/ [2] https://en.wikipedia.org/wiki/Multiple_comparisons_problem https://en.wikipedia.org/wiki/Multiple_comparisons_problem [3] https://en.wikipedia.org/wiki/Bonferroni_correction https://en.wikipedia.org/wiki/Bonferroni_correction
  - swsieber 11y ago

consta 11y ago

Impressive but I don't see the point of diagnosing Parkinsons in early stages when there is no cure available.

ars 11y ago
How do you know there is no cure for early diagnosis? Until today it wasn't possible to diagnose early.
ajkjk 11y ago
Fortunately, everybody else does. Why would we not want to be able to discern life-threatening information sooner? Not to mention the value in correlating another physiological change with the disease. Maybe research into how this works can get us closer to a cure.
- Alex3917 11y ago
  > Why would we not want to be able to discern life-threatening information sooner? Because there's a good chance you'll receive a treatment that will cause you to die sooner than had you not known about the disease for another decade. C.f. why they pushed back the recommended age for mammograms this week.
  - lightyrs 11y ago
    That is a great point. Treatment is often the nail in the coffin; Sepsis, for example.
  - ajkjk 11y ago
    That sounds like a problem with the treatment, not a reason to remain ignorant about your own health for longer.
IkmoIkmo 11y ago
Well a few quick thoughts against that: 1) Wouldn't you want to know say a year in advance, before you made all kinds of hospital visits and it was finally confirmed? I bet you would. Perhaps to start preparing for a different life, career, perhaps to advance future plans of things you'll gradually become less able to do. People want to know. 2) Can you imagine that if somehow, for example, you could detect Parkinson's by smell, that this would open up all kinds of findings, research and understanding about what Parkinson's is, how it works, how it's detected etc, that could potentially lead to better treatment or even a cure? I bet you can imagine there's a positive correlation between understanding something better and the ability to treat it in future. 3) it's simply interesting in and of itself. How curious, isn't it?

klodolph 11y ago

There are a couple people picking on this research in the thread. This is a preliminary study, just a "bullshit test" to see if this woman is crazy or if she's not. It's obvious that she's not crazy, because all she's doing is sniffing t-shirts and she doesn't know who they belong to. The sample size is large enough, we have a p-value of no more than p=0.0012, and that's under the cynical assumption that she somehow knew that exactly seven of the twelve samples would have Parkinson's... something that the scientists didn't know. So we know that something is going on here. The next steps are to control potential confounding variables and to determine the sensitivity and specificity of the test, if it's shown that she's not actually detecting some confounding variable. This is where you go double-blind, you use larger sample sizes, et cetera, now that you have money. You have money because the preliminary research was promising. And we're not just getting a good test out of this. If there's an actual chemical that she's smelling, then there's some chemical process that's going on in people with Parkinson's which isn't happening in people without Parkinson's (or vice versa). Tracing these chemical pathways could give us clues to the etiology of the disease, which would be a REALLY BIG DEAL. Or maybe it's just a rabbit hole.

cbd1984 11y ago
One of the great things about science is that we can determine whether a phenomenon is likely real without having to have the slightest clue what the mechanism might be. Evidence comes first, and this looks like solid evidence, and mechanism can come later; the evidence alone proves the existence of something interesting, and that's what's worth a follow-up. Hypothesis generation is important, because it helps us design the next experiment, but this experiment is already very interesting.
- nnethercote 11y ago
  > One of the great things about science is that we can determine whether a phenomenon is likely real without having to have the slightest clue what the mechanism might be. You just have to ignore the people who shout "correlation is not causation" at every opportunity, appropriate or not.

seccess 11y ago

My grandpa died of parkinson's, its a really slow and heartbreaking disorder. I think early diagnosis would be wonderful. It runs in the family, and his two older brothers and father had it, so he lived a very preventative lifestyle - especially with respect to daily exercise. I think it paid off, he lived to 85 while both his brothers died 20 years younger.

jarmitage 11y ago

Reminds me of this anecdote from Fishing with John: "I heard a story about this woman that was swimming in the ocean, and dolphins started swimming with her, and the dolphins kept poking her in the chest above her breast. She got scared and they took her out of the water, and she had a big bruise right on the top of her breast. They took her to the doctor to examine her, and they did a mammogram, and found that she had cancer right in that spot." – Jim Jarmusch, 'Fishing with John' https://youtu.be/uVa8rj1mm7A?t=912 https://youtu.be/uVa8rj1mm7A?t=912

lost_my_pwd 11y ago
Not sure if it is scientifically confirmed but it is believed that dolphins can see inside a body to some extent with their sonar abilities.
- jarmitage 11y ago
  Wow, link for that?
  - dewarrn1 11y ago
    I can't vouch for dolphin sonar resolving fine anatomical detail /in vivo/, but dolphins can recognize visually obscured objects using the ability [0]. [0] http://www.dolphin-institute.org/our_research/dolphin_research/seeingthroughsound.htm http://www.dolphin-institute.org/our_research/dolphin_resear...
  - tim333 11y ago
    There's a link with some stuff here http://www.livescience.com/38087-can-dolphins-detect-pregnant-women.html http://www.livescience.com/38087-can-dolphins-detect-pregnan...
harvestmoon 11y ago
Yes, and as the wise narrator of this parody series points out, "What is most remarkable about this story is not that the dolphin knew the woman was sick, but that it knew she didn't know already."

tcdent 11y ago

Interesting given the recent link between Parkinsons/Alzheimers and fungal infections: https://news.ycombinator.com/item?id=10401344 https://news.ycombinator.com/item?id=10401344

ksml 11y ago
I would not call that a definitive "recent link"; as many in that thread pointed out, that was not the greatest research and needs far more work to confirm
- tim333 11y ago
  Yeah, more research needed. I also came across another 2013 "Fungus may cause symptoms of Parkinson's disease" article I found interesting. They "found that a compound emitted by mold, called 1-octen-3-ol but more commonly known as mushroom alcohol" "attacked two genes involved in the creation of dopamine" And speculate I think that could be related to the drop of in dopamine production in Parkinsons. It would be interesting to try some such "volatile organic compounds emitted by fungi" with the lady who can smell Parkinson's to see it the smell was similar. http://www.medicalnewstoday.com/articles/268848.php http://www.medicalnewstoday.com/articles/268848.php Also a 1990 article suggesting it's "the fungus, called Nocardia asteroides." I guess nothing much happening since 1990 suggests that didn't work out. http://articles.latimes.com/1990-05-17/news/mn-286_1_nocardia-infection http://articles.latimes.com/1990-05-17/news/mn-286_1_nocardi...

conductor 11y ago

Can anybody tell us what is the current state of the art in "electronic nose" sensors technology? Could they potentially be used to identify this smell?

TeMPOraL 11y ago
We're pretty good at detecting low concentrations of chemicals in the air if we know exactly which ones to detect. This case suggests there might be some previously unnoticed substances in the air that are indicative of one's Parkinson. If so, we'll probably quickly build dedicated sensors. The thing that makes me wonder though - what's the state of broad-range chemical sensing? Could a chemical like this be found before if we kept taking broad "smell" samples of everyone and cross-correlating them?

JulianMorrison 11y ago

Seems like they are going the long way about it to determine a molecule for a test. Why not just train a dog to smell it?

jmiwhite 11y ago
Smell what? It seems that _how_ this works is still unclear, if it works at all. Once validated, it seems plausible that a device/trained animal could replicate the results, assuming its not like this guy: https://en.wikipedia.org/wiki/James_Harrison_(blood_donor) https://en.wikipedia.org/wiki/James_Harrison_(blood_donor)
KingMob 11y ago
Well, since it seems likely there's now a scent-based marker, we could train dogs to sniff Alzheimer's out, but we'd still want to know more about the molecule and biochemistry for treatment purposes.
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IkmoIkmo 11y ago

The thing that most surprised me were the odds that a person in the control group (no parkinson's), actually did have parkinson's (diagnosed early according to the woman) and was diagnosed later to indeed have parkinson's. After all, the prevalence is 0.3% in the general population. The odds at least one of the six in the control group had parkinson's is around 2% (even less considering it's already a filtered audience in a way). Not impossible but very unlikely, which incidentally makes her insistence of that single particular person to have PD all the more interesting. There's definitely something there, looking forward to more testing.

eterm 11y ago
I don't understand the phrasing there, "She was adamant". If it was a controlled test, why should she need to be "adamant" about anything, surely she would have merely identified it.
- MLR 11y ago
  She was adamant that one of the control group members (i.e. no Parkinson's) had Parkinson's.
- deleted 11y ago
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- deleted 11y ago
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- IkmoIkmo 11y ago
  I guess after the test they told her the results (i.e., you're wrong on 1 person because he's in the control group and doesn't have Parkinson's), at which point she insisted that he smelled the same as the others, and then the journalist wrote that up as 'she was adamant he had Parkinson's'. Or she really did fully believe in her sense of smell as an ability to detect Parkinson's without doubt, at which point it as much sense for her to say a person has Parkinson's as you to say the sky is really blue because your eyes tell you and the journalist simply relayed that. There's various readings of the phrase that can make sense.

cafebeen 11y ago

Looking forward to hearing more--reminds me of work done to detect cancer by scent with help from dogs: https://en.wikipedia.org/wiki/Canine_cancer_detection https://en.wikipedia.org/wiki/Canine_cancer_detection

tomcam 11y ago

Galen relied on sense of smell for diagnosing illnesses. Aristotle wrote about it. Until the late 20th century doctors often used smell for diagnostics.

Mz 11y ago

This also reminds me of the breathe test being developed to check ammonia levels for certain kinds of patients: https://news.ycombinator.com/item?id=10402816 https://news.ycombinator.com/item?id=10402816

andy_ppp 11y ago

Some more truly fascinating Parkinson's news this week about nilotinib, apparently seeming to cure Parkinson in small trials... http://www.independent.co.uk/life-style/health-and-families/health-news/parkinsons-patients-given-new-lease-of-life-after-receiving-cancer-drug-in-trial-a6699031.html http://www.independent.co.uk/life-style/health-and-families/...

tim333 11y ago
Thanks for the link. There is another article in the New Scientist with more information https://www.newscientist.com/article/dn28357-people-with-parkinsons-walk-again-after-promising-drug-trial https://www.newscientist.com/article/dn28357-people-with-par... I'm on the look out for stuff for my dad who seems to have it. The data in the New Scientist article looks promising - all 12 of the patients started to improve, some dramatically and as to side effects the "team saw no unwanted effects".

bazillion 11y ago

This reminds me of when I was in the Navy -- at one point I had lived with hundreds of other guys in a ship's berthing and at another duty station I mentioned to a coworker that I could determine someone's race from their sweat. Of course, they called bullshit on that statement (as I'd imagine most on here would) and we tested it out with 4 guys (1 black[1], 2 white[2], 1 hispanic[3]) who sweated into the same size shirts, and I was able to identify them with 100% accuracy. Another time, I walked into a cubicle, wrinkled my nose, and said "Man! It smells like an old deck of cards in here!". One of the guys standing next to me then pulled out a rather well-played-through deck of cards out of his pocket. One of the reasons people give for the difference in smell are the difference in foods that different cultures eat. I definitely know this is not the case, as everyone on that ship was eating the exact same food, and their smells were extremely distinct. I understand that lack of science applied to my specific anecdotes, but I think there's something to be said for having a keen sense of smell, since people are already geared towards smelling other people's sweat to determine immunocompatibility[4]. [1] A black person's sweat is the one I can identify with absolute certainty, as it's completely unmistakable for anything else [2] A white person's sweat smells like a distinct type of onion to me [3] I couldn't really identify his race if it were just this shirt, but had that one by process of elimination. [4] https://en.wikipedia.org/wiki/Major_histocompatibility_complex_and_sexual_selection#MHC-mediated_mate_choice:_case_studies https://en.wikipedia.org/wiki/Major_histocompatibility_compl...

gohrt 11y ago
Different races definitely smell different; it shouldn't be surprise that a sweaty shirt contains that smell.
JoeAltmaier 11y ago
I hear anecdotally that Japanese think Americans smell like butter.
- lovemenot 11y ago
  It is frowned on now, but in former decades some uncouth Japanese would say "Cheezu nioi" (smells like cheese) when encountering a foreigner.

firebones 11y ago

It would seem there are some major confounding factors here not detailed in the article. 1) The population doesn't reflect a realistic test--if the overall incidence is 0.3%, but the sample size had 50% (or more given her adamant hit), then we need to know whether she was expecting more. 2) More importantly, the incidence in men is 1.49x that of women [1], and age also plays a factor. So given that the sample is already skewed towards a higher incidence of positives, the gender differences might be factored into her senses--especially since it was her husband who was her training set. With n=12, it would be very easy for the probabilities/priors to be much different than truly random. (E.g., the learning function of her nose might be "men + people over 65" which happened to match up with the test and control group quite well.") Or it could tune into medication used to treat the disease. Great if true, but I am skeptical. [1] http://jnnp.bmj.com/content/75/4/637.full http://jnnp.bmj.com/content/75/4/637.full

KingMob 11y ago
If you look at the Bayesian analyses and the frequentist analyses assuming she knew how many AD shirts there would be, you'd see that point 1 doesn't matter. We can statistically test this without the need to make her sniff 1000's of shirts. Point 2 is interesting though, and the first thoughtful criticism I've seen in the thread. What if she's both a bit lucky, and also picking up on some correlated marker like age/gender?

Optimist45 11y ago

I know the odor she is talking about. My husband was diagnosed in January. His previous truck and his current vehicle have developed a very distinct odor. I used to say old musty Portuguese man but I realize it is the smell she is talking about. My husband has only used deodorant for 27+ years. This came about because anti-perspirant made his entire armpit swell with bright red welts. He also does not sweat much. It is a very sad disease, but will continue to search for ways to make it easier.

nyc111 11y ago

The question they did not ask what makes the body smell. When we eat garlic we smell like garlic. So the smell must be related to how the food is digested. The researchers should look at the gut flora, in other words they should do a study similar to this https://news.ycombinator.com/item?id=10439129 https://news.ycombinator.com/item?id=10439129 All disease start in the gut.