I predict that the prevalence of autism spectrum disorders is done increasing because it has all come from better diagnosis. The autism rate in children has now reached one in 88; the autism rate in adults is estimated at one in 86. We just went within my error bars.

There are two things that I think could confuse the issue. The first is that the DSM-V will come out soon. If, following the DSM-V, diagnosticians continue exactly what they're currently doing, except that they diagnose all autism spectrum disorders as autistic disorder (which will not affect the one in 88 statistic because Asperger's and PDD-NOS have always been part of it), then the prevalence rate has stopped increasing. If, following the DSM-V, diagnosticians do what it tells them, the prevalence rate will decrease, with the loss coming from people with PDD-NOS who have communication or language difficulties and one of the other two points in the triad of impairments.

The second is that the adult rate may be lower than the childhood rate because of the existence of people who are diagnosable as children but not as adults because of learned coping skills. If that's true, the rate may continue to increase.

I will consider myself right if it reaches one in 84, slightly surprised at one in 80 (I'll assume I underestimated the number of people diagnosable only as children), shaken and looking for explanations at one in 75 and outright wrong (I will abandon the theory and concede defeat) if the prevalence reaches one in 70 without some really significant evidence of overdiagnosis.

I also allocate some probability mass to the idea that the prevalence rate will decrease. I don't predict a huge decrease with great likelihood, but if I do see one, I will update on my beliefs about diagnosticians and watch who is and isn't getting diagnosed in the next youngest cohort. If the DSM-V causes such a drop, I would expect it to more likely be sudden as doctors adopt changes after the DSM-V comes out, but it could be slow and steady if older doctors do as they were already doing and younger doctors act differently. Those cases could be distinguished by looking at diagnoses made by older doctors and newer ones and comparing them.

I note that while I do not predict a huge drop with great probability, mine is the only theory which would explain any drop at all.

I predict that if there is a drop, John Best will claim that "lying neurodiverse psychopaths" are somehow responsible and that it harms "actual autistics" and their families. Note that I assign only small probability to the actual phrases given. For instance, he may suggest "real autistics" or "families actually affected by real autism" or any number of things. ("Psychopaths" will be in there somewhere as a description of people who do not want a cure for autism. If he doesn't call them liars in his blog post, they will be called liars somewhere in the comments.) If I am wrong, the most likely other possibility is that he is triumphant and believes that his supporters are "getting the message out" and parents are not vaccinating anymore. My model of reality takes a hit if John Best ever claims that new and surprising evidence does not support his ideas about autism. This does not apply to everyone who is against vaccines. It only applies to him. 

(Trivial prediction: you will get upset if you read his blogs. Don't go looking for them unless your utility function values becoming upset over false claims.)

If the autism rate is stable, this is evidence that it has been stable for a long time (I believe this because the increasing rate has been used as evidence that it did not exist before the last century and that it is environmentally caused) and if it has been stable for a long time, this is evidence against it being caused by vaccines, because that would have caused the prevalence to increase.

Please spread this around as much as possible. I am predicting ahead of time that: The autism rate does not go above one in eighty, probably stays stable in the high-to-mid eighties and may decrease. I admit that I was wrong if it reaches one in seventy. Please help: I want this well-known. I want people to know I made the prediction before we see the evidence. Sharing a link to this would be a quick and easy way to increase average utility and expose people to the idea of falsifiable ideas that make predictions about what they will and won't see.

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Ever since reading West Hunter I've been intrigued by the idea of mutational load as an explanation for increasing prevalence of mental disorders. It would mean chance of having these disorders would increase with increasing paternal age, and in fact that's what we find. Since everyone's waiting longer to have babies nowadays, that explains some of the change.

I wonder if increasing paternal age explains even more of the change than that article lets on, just because it's accumulating over generations; it's not just that your dad was older, it's that your grandfather was older and therefore your father started with more mutations and so on. You can't measure that effect just by separating people into autistic and neurotypical and then asking them how old their fathers were.

Why do you think it's accumulating over generations? It hasn't been recently in Iceland, at least:

Stefánsson’s team scanned demographic records in Iceland for the average paternal age starting in 1650. From 1900 to 1980, as the Icelandic population transitioned from agricultural to industrial living, the average paternal age dropped from 34.9 to 27.9 years. In the subsequent 30 years, however, thanks to better education and higher contraception use, the average age has gone back up, to 33 years in 2011.

I would certainly expect that the category "bad effects of lifestyle changes favored by highly educated researchers" would be understudied, relative to studying the nasty effects of poor-folks culture.


Under a simple assortative mating model written recently by Hays Golden (via MR), conservative* estimates of prevalence change will continue for multiple generations; excerpts.

* Conservative because his model assumes no underlying allele change, purely changes in mating patterns; in reality, we can expect increase in autism-related alleles, I think.

I've never quite bought the diagnosis thesis as a complete explanation - assortative mating seems plausible as a contributing factor, and implies the rate won't stabilize anytime soon.

So I think this calls for a bet or at least more precise prediction: what probability do you assign to you being right; what exactly what rigorous objective data-source would you or a neutral third-party use to judge this; and what time-frame will this be true or false in?

(I would also like you to claim this account under either your real name or a pseudonym you've invested a lot in, so you can't simply pretend it never happened if you're wrong or lose the bet - give a reason to not ignore you as either willfully increasing counterparty risk or gambling on being right and then claiming it publicly in the future.)

I hereby claim that I am not-allistic on tumblr.

Tumblr doesn't let you respond to posts, so I'll do it here:

You discuss a comic in a recent Tumblr post. The scene with the snowglobe is actually a reference I think you missed. Specifically, the last episode of the 1980s-era TV show St. Elsewhere, in which it's suggested that the entire show took place in the imagination of a child whose parents say he is autistic.

From Wikipedia:

"The Last One"

The 1988 final episode of St. Elsewhere, known as "The Last One", ended in a context very different from every other episode of the series. As the camera pans away from the snow beginning to fall at St. Eligius hospital, the scene changes to Donald Westphall's autistic son Tommy, along with Daniel Auschlander in an apartment building. Westphall arrives home from a day's work, and wears clothes suggesting that he is a construction worker. "Auschlander" is revealed to be Donald's father, and thus Tommy's grandfather. Donald laments to his father, "I don't understand this autism. I talk to my boy, but...I'm not even sure if he ever hears me...Tommy's locked inside his own world. Staring at that toy all day long. What does he think about?" The toy is revealed to be a snow globe with a replica of St. Eligius hospital inside. Tommy shakes the snow globe, and is told by his father to come and wash his hands, after having left the snow globe on the family's television set.[1]

One of the more common interpretations[citation needed] of this scene is that as Tommy shakes the snow globe in the apartment, he also makes it snow at the "fictional" St. Eligius. His father and grandfather also seem to work at this hospital even though neither man has ever experienced such a role. By implication this interpretation suggests the total series of events in the series St. Elsewhere had been a product of Tommy Westphall's imagination.

This comic is applying the same conceit to Foster's Home For Imaginary Friends.

Then St. Elsewhere, rather than the comic, is problematic and wrong. Thank you; I wouldn't have known that had you not told me.

I'm still glad to have put that up on tumblr because I still don't want people thinking that's an accurate portrayal of autism.

I hereby claim that I am not-allistic on tumblr.

I have no idea who that is, and googling I just see a bunch of tags. (Also, you didn't answer the other questions.)

Tumblr urls are formed like this:


Thank you, I've now had time to read your post a second time and parse your other questions. Here are my answers.

(What is counterparty risk, by the way?)

The CDC will be an adequate source for this. I don't know and can't figure out how to find out when they'll next release an estimate of how common ASDs are. If they do it before the DSM-V comes out or shortly after it comes out, then I would wait and take not the next but the one after. If they wait until the DSM-V has been in use for a while, and I'm not sure how long a while should be, then maybe just the next one.

I am not well-calibrated enough to give good probability estimates and I worry that I'd just be making something up if I tried to give a number. I also revised down slightly from six hours ago considering what you and Yvain have said. I still think having this out there, even imperfectly, is of social utility because until recently, the better diagnosis model and the epidemic model had both predicted increasing prevalence. I wouldn't bet on it because, among other reasons, this prediction isn't really about proving me right or wrong. It's about proving a model right or wrong. If that model is wrong, then I update. I change my beliefs and actions, but then I move on. I don't "change sides" or anything like that. However, the model stands or falls here (or at some future predetermined point farther on, if one in 86 is still not the correct prevalence) and if it's going to survive, I want to see it believed by everyone, partly because proving this model eliminates the vaccine injury model (among others). You, who have reasoned that accumulated mutations are a reasonable model, are really not my opponent here.

I also admit that I want this model to be true because even without the hard work of educating people, it would show that there's no epidemic to be scared of, which might make educating people easier. That could cloud my judgment, but an empirical test will not have clouded judgment.

Fair enough?

The CDC will be an adequate source for this. I don't know and can't figure out how to find out when they'll next release an estimate of how common ASDs are.

My general experience with this sort of thing is that the dataset will be rich and include many different ways of slicing the data and with multiple definitions, so it's possible to pick and choose numbers to get what you want. Hence, specifying 'CDC' is better than specifying no source of data at all, but to make a good prediction one should specify the specific metric in the CDC surveys or reports.

I am not well-calibrated enough to give good probability estimates and I worry that I'd just be making something up if I tried to give a number. I also revised down slightly from six hours ago considering what you and Yvain have said.

If you can't give a good probability estimate, then no one here will take you seriously nor will you be able to make or accept bets (so no one outside here will take you seriously either). If you want to learn how to do this, my own opinions can be found in http://www.gwern.net/Prediction%20markets

You, who have reasoned that accumulated mutations are a reasonable model, are really not my opponent here.

That's Yvain, not me. I read the recent correlative study like everyone else and find it interesting, but I'm not sure how persuasive I find it.

Fair enough?

If you're really serious about it... What I would've done, if I had this sort of big public statement in mind, is written up a brief precis of why the diagnosis model is right, why I expect diagnosis-driven increases to level off soon (in stock market shorting, they have an expression: 'don't try to catch a falling knife'. When you short a stock, knowing when to start shorting is as important as knowing what is overpriced, because 'the market can stay irrational longer than you can stay solvent'), what my exact metrics will be, what probability I assign over what periods, cryptographically sign my statement, and challenge some prominent anti-diagnosticers to bets on those terms - ideally through LongBets.org for nice round sums like $100, $500, or $1000.

Is this a lot of work? Yes! But you are trying to buy credibility, attention, and change minds down the line; you should not expect that to be cheap or easy.


(What is counterparty risk, by the way?)

The risk that if you lose the bet, you don't pay up. It's relatively high here because a single-purpose account has no reputation to care about.

Especially since he immediately stopped commenting (last comment November 2012), and there's no way to track him down to a real name, so if one had made a bet with him and won, how could one collect?

Please help: I want this well-known. I want people to know I made the prediction before we see the evidence.

If it's important to you that people know you make the prediction than you should attach your name to the prediction. Anonymous online predictions don't have much value in the public discours.


In the spirit of constructive criticism:

I wouldn't worry much about John Best. He's obviously fringe / crackpot - more effectively ignored than explicitly addressed.

Just my two cents as a peripheral participant in special needs advocacy. Since you are more involved in the advocacy movement, your perspective may be different.

I concur, he's not worth taking seriously. However, when he and less-ranty people say the same things all the time and they're aimed at you, it hurts less if you point out (not in any of his spaces, obviously) that he's being irrational and ridiculous. You are correct that engaging with him directly would be a bad idea and writing a thoughtful critique of his ideas would probably be wasted effort. That's why you don't see me commenting on his blogs. I'm just needling here. It's also there for anyone else who's read his stuff and felt insulted, angry or heartsick to read and realize no one believes him. (My entire online not-allistic identity is designed to make autistic people feel better when they read it.) Best is also so easy to mock that I'm not fully convinced he's not a troll, but that's a lot of effort for a troll to go to over quite a long period of time.

Thank you for your advice, however.