I’m going to contend tonight that autism is a growth disorder whose prevalence increases with advancing average birth weight and height and which explodes in frequency when weight and height can increase no further, resulting in a kind of "spillover" of growth into the brain.
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A question to ask yourself is: do you think this brain overgrowth at the same regardless of how nutrition the developing child was receiving? The body’s growth slows down when malnourished; is the brain an exception to this rule?
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Studies on young autistics sometimes find them to have elevated levels of growth factors like IGF-1/ IGF-2 and growth hormone binding protein. You may know of IGF-1 as the protein that becomes elevated by dairy consumption and can produce acne. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.465.4652&rep=rep1&type=pdf …
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As of 2021 only a very small percentage of autism’s genetic risk can be accounted for by named genes, but an unusual number of risk genes overlap with growth and cancer promoting pathways like mTOR, IGF, and PTEN.https://www.sciencedirect.com/science/article/abs/pii/S0736574814000409 …
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MTOR hyperactivation seems to be the primary cause of tuberous sclerosis, a condition in autism co-exists at a frequency of 25-50%. TS patients have large growths on their skin that are paralleled by growths in their brains (tubers)https://en.wikipedia.org/wiki/Tuberous_sclerosis …
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Interestingly, one of the minor physical abnormalities more common in autistics than controls is a high number of moles, which invites an obvious comparison to TS. Autistics have a tendency to produce growths everywhere.
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These same genetic pathways interestingly also stimulate aerobic glycolysis, converting glucose to lactate (which is high in autistics) regardless of oxygen status, producing very little energy at high metabolic cost:https://molecularbrain.biomedcentral.com/articles/10.1186/s13041-017-0343-6 …
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Although the above paper does not focus on this, aerobic glycolysis (the Warburg effect) stimulates the growth of tumors. Its role in autism would help to explain why a number of autistics seem to improve under a ketogenic diet or when they fast.https://www.sciencedirect.com/science/article/abs/pii/S1750946715001099 …
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Glycolysis is also important in that I think it can demonstrated that differences in metabolism underlie the physical and athletic differences between generations.
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One of the striking differences between present- day faces and those born before the WWII is just how soft, doughly, and unmuscular old faces were. If you think you this composite from Dienekes Pontikos is unrepresentative, look at pictures of your great-grandma:pic.twitter.com/QeUUOeAF5G
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The general trend as far as looks go is that present day women are vastly more beautiful and athletic looking on average than those in the past, whereas in the change is more ambiguous (I think they’re a little less handsome).
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Many people don't like the idea, but older generations were not just shorter, but weaker than those in the present day. The physical gap between the Boomers and their parents was so large than the old timers themselves admitted it:https://www.youtube.com/watch?v=FZo2hhvvlpw&t=43s …
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A weird experience a lot of people have when watching old movies is seeing a stunningly handsome 50’s actor take off his shirt to reveal an ugly, flabby, emaciated body:https://www.youtube.com/watch?v=__vqb7mei9Q …
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There are a lot of 12 year olds who watch basketball or soccer from the 80’s and mock the slowness of the athletes, while their wise elders instruct that either 1. Those guys didn’t have fancy weightlifting/nutrition or 2. The old guys were actually better. Neither is true.
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While heights have stopped growing, every upcoming cohort of young people is more athletic than the last, even while their hands and fine motor skills are weaker. There were not janitors in 1975 with the athleticism of Zion or Lebron waiting for NBA salaries to go up.
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When Kevin Durant entered the NBA he was roundly mocked for not being able to bench 180 pounds on draft day. But in 1986 the Nigerian born Hakeem Olajuwon’s teammates teased him for not being able to lift 130. People who grow up malnourished and inflamed are different.
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What explains the difference in strength? Since birth weights went up for decades, one way to approach the problem is to ask why low birth weight infants are so weak as adults.
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One of the mechanisms is that insulin-stimulated glycolysis is less effective in low birth weight infantshttps://academic.oup.com/jcem/article/92/4/1530/2597860 …
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I think the underlying metabolic difference between generations is that older people tend to oxidize fat into energy more easily, which contributes to their thinness and vigor, but also ages them faster as opposed to younger folks who tend to store fat/muscle instead.
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The best illustration of “spillover” is the incredible increase in the size of the ass and thighs in girls. This is not due to squatting or implants, because you see it at very young ages. There are 1st grade girls in 2021 that have asses that didn’t used to show up until 16.
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The way to utilize this information to understand autism treatment is to look expectantly toward the use of PPAR agonist drugs like pioglitazone or fenofibrate which upregulate fatty acid oxidation
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A few months ago I wrote a thread which detailed how grip strength has declined in the West universally, to the point where most top arm wrestlers are over 40, even though grip strength declines at 30.https://twitter.com/crimkadid/status/1312567390148931587 …
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What was really stunning was that when you looked at the age of the competitors there was a huge drop off in those born after 1980. In the US and North Europe, the first cohorts to attain maximum adult height were born around 1978.
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My belief is that kids born around the same year as Tom Brady received the maximum beneficial dose of growth and nutrition before we reached some kind of Omega Point that natural selection had never designed us for.
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Starting in the 1980’s after increasing steadily for decades, birth weights peaked and then progressively declined in wealthy countries around the world. The most complete figure I could find comes from Japan, where the decline began around 1980.pic.twitter.com/S9H0OGWmTD
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For most of history the average North European male height was 5’5-5’6”, with exceptionally good conditions leading to heights of up to 5’8”. Through most of history people never even came close to maxing out their size, producing a problem natural selection has yet to solve.
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If you have autistic relatives, you might be curious how this kind of growth spillover actually leads to autism. My stance is that much of autism qualifies as “precocious depression”, in which normal depressive symptoms occur so early as to become fixed.
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The strongest genetic overlap between autism and another measurable quality is with depression and low well-being. Interestingly, some of the genes that increase autism risk also improve IQ, which is the opposite of what you see in schizophrenia and ADHD.pic.twitter.com/bochHxlwrS
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Depression and autism are both characterized by low levels of brain blood flow; from a certain fmri point of view autism doesn’t look _like_ depression it looks like it IS depression, but depression that begins at an abnormally early point in development.
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When people become depressed they undergo mental declines in areas like psychomotor speed and episodic memory for real events that sometimes outlast the depression by months. The decline in memory leads to a kind of self-centered rumination reminiscent of autism.
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Hopefully that makes sense, but what’s much more baffling is how exactly autism would be associated with high intelligence, likely having something to do with their overgrown frontal lobes.
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