3 ms·

The preservative in question is propionic acid (PPA): > In the current study, Saleh Naser, PhD and her team at UCF found that when neural stem cells were expos

by ex3xu 7y ago

The preservative in question is propionic acid (PPA): > In the current study, Saleh Naser, PhD and her team at UCF found that when neural stem cells were exposed to high levels of PPA, the neurons incurred multiple changes resulting in cellular damage and inflammation. One of the major effects of PPA they noted was the overproduction of glial cells, the protective outer cells making up the sheath covering neurons, with a corresponding reduction in the number of neurons themselves. Here's another article covering some more of the etiological history behind this finding: https://www.foundationalmedicinereview.com/blog/the-link-between-propionic-acidemia-and-autism-spectrum-disorder-may-offer-etiological-clues/ https://www.foundationalmedicinereview.com/blog/the-link-bet... On a side note: at the risk of both being slightly off topic and/or spreading bad science, there was that controversial assessment of Einstein's brain which noted that he had a higher proportion of glial cells than other brains studied (see Wikipedia for potential issues with the findings): https://en.wikipedia.org/wiki/Albert_Einstein%27s_brain#Glial_cells https://en.wikipedia.org/wiki/Albert_Einstein%27s_brain#Glia... I'm noting this only as a layman's speculation about glial cell concentration as a potential mechanism behind the phenomenon of higher intelligence and occasionally savant-like abilities in some of the high-functioning ASD population.

nickpsecurity 7y ago
I was wondering about that, too. Inspired in part by articles like this: https://www.scientificamerican.com/article/the-root-of-thought-what/ https://www.scientificamerican.com/article/the-root-of-thoug...
- ex3xu 7y ago
  Thanks for sharing, I'll have to look into that book sometime. Also a real throwback to see Jonah Lehrer's name on a piece of scientific journalism. Looks like in 2018 there's a few [0] interesting [1] papers [2] on the link between senescent glial cells and neurodegeneration, which I think would support a theory of glial cells playing some role in cognition. Seems to be a fairly active area of research. [0]: https://www.nature.com/articles/s41586-018-0543-y https://www.nature.com/articles/s41586-018-0543-y [1]: https://www.researchgate.net/profile/Jay_Penney/publication/327752923_Elimination_of_senescent_cells_prevents_neurodegeneration_in_mice/links/5bd4a056299bf1124fa749fc/Elimination-of-senescent-cells-prevents-neurodegeneration-in-mice.pdf https://www.researchgate.net/profile/Jay_Penney/publication/... [2]: https://www.sciencedirect.com/science/article/pii/S0896627318309978 https://www.sciencedirect.com/science/article/pii/S089662731...
gowld 7y ago
Were the "high levels" of PPA food level, or 100x total human lifetime exposure? This is very preliminary speculative science that shouldn't be oversold.
- ex3xu 7y ago
  The elevated levels of PPA are linked to a dysbiotic gut bacteria imbalance, with ASD children exhibiting more bacteria that produce PPA. I'd imagine if you're not eating PPA in excess of your body's ability to metabolize it you're fine. Regarding the second half of your comment, I'll cite from the etiology article I linked: > In the concluding sentences of their analysis, Witters and Debold make their strongest argument for the connection between propionic acid and ASD by observing that, given the rates of PA [proprionic acidemia] and of ASD occurrence in the general population, the probability of there being no link between the two pathologies is 4.34 in 10 trillion. Put differently, comorbid incidences of PA and ASD are far more common than should be expected between two unrelated diseases, meaning that there is most likely a link between the two.
  - gus_massa 7y ago
    How did they make the calculation? From the same article: > Research produced in 2016 by Drs Peter Witters and Eric Debold corroborates the link between the two conditions in a longitudinal study of 12 patients investigating blood metabolite balance in patients with PA and behavioral disruptions. From https://en.wikipedia.org/wiki/Propionic_acidemia https://en.wikipedia.org/wiki/Propionic_acidemia the incidence of PA is 1/3500 and from https://en.wikipedia.org/wiki/Autism_spectrum https://en.wikipedia.org/wiki/Autism_spectrum the incidence of ASD is 1/100, so assuming independence it's expected that you can find in the word 7000000000/3500/100 = 20000 person with both illness, and they are analyzing a group of 12 patients with PA and only 5 have clear ASD and other 3 have only some symptoms of ASD.
    - ex3xu 7y ago
      You're right that it's a low sample size, and the authors themselves do warn that diagnostic rates of ASD in children may be inflated: > With the increasing reported frequency of ASD in the pedi-atric population one cannot rule out a possible coincidence of the diagnosis of ASD in patients with propionic acidemia. Regarding the calculation, Wikipedia says 1 in 35000 for PA the US, rather than 3500, and the researchers use an incidence rate of .5% for autism rather than 1%. So the number of people is 1000, not 20000. The researchers say they're calculating off a 5/8 ASD/PA incidence rate, so the calculation is something like (1000/7 billion)^5*(some negligible amount)^3.

by ex3xu 7y ago

nickpsecurity 7y ago

I was wondering about that, too. Inspired in part by articles like this: https://www.scientificamerican.com/article/the-root-of-thought-what/ https://www.scientificamerican.com/article/the-root-of-thoug...

ex3xu 7y ago
Thanks for sharing, I'll have to look into that book sometime. Also a real throwback to see Jonah Lehrer's name on a piece of scientific journalism. Looks like in 2018 there's a few [0] interesting [1] papers [2] on the link between senescent glial cells and neurodegeneration, which I think would support a theory of glial cells playing some role in cognition. Seems to be a fairly active area of research. [0]: https://www.nature.com/articles/s41586-018-0543-y https://www.nature.com/articles/s41586-018-0543-y [1]: https://www.researchgate.net/profile/Jay_Penney/publication/327752923_Elimination_of_senescent_cells_prevents_neurodegeneration_in_mice/links/5bd4a056299bf1124fa749fc/Elimination-of-senescent-cells-prevents-neurodegeneration-in-mice.pdf https://www.researchgate.net/profile/Jay_Penney/publication/... [2]: https://www.sciencedirect.com/science/article/pii/S0896627318309978 https://www.sciencedirect.com/science/article/pii/S089662731...

gowld 7y ago

Were the "high levels" of PPA food level, or 100x total human lifetime exposure? This is very preliminary speculative science that shouldn't be oversold.

ex3xu 7y ago
The elevated levels of PPA are linked to a dysbiotic gut bacteria imbalance, with ASD children exhibiting more bacteria that produce PPA. I'd imagine if you're not eating PPA in excess of your body's ability to metabolize it you're fine. Regarding the second half of your comment, I'll cite from the etiology article I linked: > In the concluding sentences of their analysis, Witters and Debold make their strongest argument for the connection between propionic acid and ASD by observing that, given the rates of PA [proprionic acidemia] and of ASD occurrence in the general population, the probability of there being no link between the two pathologies is 4.34 in 10 trillion. Put differently, comorbid incidences of PA and ASD are far more common than should be expected between two unrelated diseases, meaning that there is most likely a link between the two.
- gus_massa 7y ago
  How did they make the calculation? From the same article: > Research produced in 2016 by Drs Peter Witters and Eric Debold corroborates the link between the two conditions in a longitudinal study of 12 patients investigating blood metabolite balance in patients with PA and behavioral disruptions. From https://en.wikipedia.org/wiki/Propionic_acidemia https://en.wikipedia.org/wiki/Propionic_acidemia the incidence of PA is 1/3500 and from https://en.wikipedia.org/wiki/Autism_spectrum https://en.wikipedia.org/wiki/Autism_spectrum the incidence of ASD is 1/100, so assuming independence it's expected that you can find in the word 7000000000/3500/100 = 20000 person with both illness, and they are analyzing a group of 12 patients with PA and only 5 have clear ASD and other 3 have only some symptoms of ASD.
  - ex3xu 7y ago
    You're right that it's a low sample size, and the authors themselves do warn that diagnostic rates of ASD in children may be inflated: > With the increasing reported frequency of ASD in the pedi-atric population one cannot rule out a possible coincidence of the diagnosis of ASD in patients with propionic acidemia. Regarding the calculation, Wikipedia says 1 in 35000 for PA the US, rather than 3500, and the researchers use an incidence rate of .5% for autism rather than 1%. So the number of people is 1000, not 20000. The researchers say they're calculating off a 5/8 ASD/PA incidence rate, so the calculation is something like (1000/7 billion)^5*(some negligible amount)^3.