After learning former US president Bill Clinton had indicated he believes that “the number of children who are born with autism [is] tripling every 20 years” (hat tip Orac), an understandable reaction might be to point out his ignorance. Understandable, yes, but I think we are looking at a bigger problem than lack of scientific literacy or political pandering in this case; a problem that is going to have to be addressed in a manner that is clear and generally convincing.
A lot of the discussion in the autism community centers around the anti-vaccination movement. It is true that anti-vaccination could potentially become a major problem for the world as a whole, and it is also true that it is a source of stigma for autistics. Some of us have taken it to be our fight, even though it should probably be the CDC’s or the WHO’s fight, if they were not, as it seems, asleep at the wheel. Nevertheless, I think the persistent autism epidemic meme is a much bigger issue as far as the autism community is concerned. Not only is the notion of an epidemic stigmatizing, but it results in ideas that are more than just theoretically harmful to autistics, such as the idea that autistic adults don’t exist. These ideas will be around regardless of the existence of an anti-vaccination movement.
In my regular blog I have discussed the evidence against the notion of an autism epidemic at length. If I may say so myself, I might have even managed to half persuade a few people from the other side of the debate.
What I want to do here, however, is to essentially critique the evidence I’ve discussed thus far. Let me explain why.
Those of us who are immersed in scientific discussions involving autism are well aware, for example, of diagnostic substitution, of an apparently high prevalence of autism in adults, of the changing characteristics of autistics over time, of regional prevalence differences that resemble time-dependent differences, of the stability of cognitive disability as a whole, of the stability (even the decline) of institutionalization rates, of what went on in the past, and so forth. Taken as a whole, this evidence is overwhelming and convincing to someone such as myself who has studied and perseverated on it for years. Fundamentally, though, it is evidence that has a number of problems: It is too numerous, complex, disjoint and most importantly, lacking in precision; none of it is decisive on its own. We are talking about many bits and pieces of evidence that need to be put together and thought through in order to arrive at the conclusion that there is no such thing as an autism epidemic. I don’t expect someone such as Mr. Clinton to be aware of this evidence, understand it, or think through it, much less be able to analyze some of the publicly available data that is not yet available through the scientific literature.
You see, there’s no such thing as an IOM report on the autism “epidemic.” While I’m personally not that fond of basing my beliefs on what authority tells me I should believe, I think a pronouncement by major authorities on the matter would help inform the general public of the state of the debate and the evidence. For this, however, I believe additional research that specifically addresses the matter in a clear way is needed. Allow me to propose some avenues of future research that could potentially answer the remaining questions once and for all. I encourage readers to propose their own ideas.
1) Replicate Lotter (1967). We know that the prevalence of autism as currently defined is relatively high. We also know that the prevalence of autism as defined in the 1960s was relatively low (4.5 in 10,000). What we don’t know is whether the prevalence of autism ascertained using Lotter’s operationalized criteria and methods is still relatively low in 2008. I think it should be feasible to replicate Lotter’s methodology and criteria today and find out the prevalence, not of DSM-IV autism, but of autism as it was thought of in the past. Without meaning to be disrespectful, this should preferably be done while Lorna Wing is still with us. She claims to know which kinds of children Vic Lotter considered autistic and which he didn’t.
2) Determine the prevalence of autism in adults. This one is non-trivial, as there are some ethical issues to consider, but it seems they will attempt it in the UK. I hope it’s not another case of trying to find how many adults are diagnosed with autism or receiving services under an autism category. This wouldn’t teach us anything new and would just be fodder for David Kirby’s blog. I also hope they don’t assume all autistics must be psychiatric patients, for example. They should find a lot of autistics in the general population, and there is evidence they should find many who might not be diagnosable with autism despite meeting criteria, for various technical reasons. Of course, they also need to look in institutions and group homes, since a ready rebuttal will be that “low functioning” autism must therefore be what’s rare in adults.
3) Determine if regional differences in prevalence are real. When you study administrative databases in some detail, one thing that immediately jumps out is that there are huge disparities in the administrative prevalence of autism between certain regions, be it states, regional centers or counties. I have reasons to believe these differences are not real. If these differences are not real, I’d suggest it would be reasonable to hypothesize that time-based differences in administrative autism prevalence are of the same nature. I have suggested, for example, screening children with mental retardation from different regional centers in California to determine, at the very least, if there are real discrepancies in the prevalence of autism within the population with mental retardation. Another question that needs to be answered is why population density correlates so well with administrative prevalence (independently of things like environmental pollution, as I’ve recently found).
4) Explain the changes with a mathematical model. The plausible mechanisms that explain the rise in diagnoses of autism have been discussed at some length. They might include increased awareness, changes in official criteria, an increased availability of specialists, an increased availability of certain services, changes in cultural beliefs, and so on. I have even discussed the internet as a potential driving force behind increased awareness, particularly in the 1990s. But let’s face it, these are all essentially unproven mechanisms. No one has done a multivariate analysis that gives us a coefficient for each variable. Granted, some things are hard to quantify. It would be a lot like trying to quantify word of mouth. But some of this should be doable.
Left Brain Right Brain 
Woo who?
“Woo” as you like to call it comes in many varieties. If you are seriously suggesting that you can definitively say there are no environmental contributors to the startling increases in autism diagnoses then you are simply spreading your own variety of woo.
I’d like to see “epidemiology” done on the disappearance of certain categories of diagosis. Like how quickly did the numbers of “childhood schizophrenia” drop and when? How about “minimal brain dysfunction”? How about the reverse “epidemic in mental retardation”? What is happening to those kids if they aren’t being rediagnosed as autistic?
Has there been a corresponding drop in the money spent on kids with “MR” as we see the increase in money spent on “autism”? (I’d think so.)
There are something like 10 or 20 old and current psychiatric labels that have been applied to people with traits that seem also to be part of autism. Why aren’t we discussing all of them now? What happened to “mental retardation with autistic features”? How close is “schizoid” personality disorder to autism and how likely would it be for someone to confuse them if they weren’t well trained in identifying autism?
How many people were well trained in identifying autism 20 years ago? How many are now? Is this number leading the “autism epidemic”? If you introduce a diagnostician to a small town, if they start practicing in a town where there was no one diagnosing autism previously, is it followed by an “outbreak of autism diagnoses” in all age groups?
If you add an ABA or Floortime therapist to a town, will there be a sudden outbreak of autistic children?
If you are seriously suggesting that you can definitively say there are no environmental contributors to the startling increases in autism diagnoses then you are simply spreading your own variety of woo.
Why? The burden of proof is not on me. It’s on whoever proposes a potential cause.
Can I definitely say there’s no such thing as an autism epidemic? Yes. I’ve discussed the reasons at length. They are complicated, but they are there. If you don’t like it, prove me wrong, Harold.
Even David Amaral who has basically gone along with the idea of an epidemic in the past is now saying that there’s no evidence for an epidemic. He says there may be evidence for a real increase, but we don’t know how much it is.
That’s what all the skeptics been saying for a few years now.
The thing is, if the “view” of a thing is so fuzzy that you can’t tell if it’s growing or shrinking, then it generally tends to mean that it’s not growing or shrinking very much. In other words, if you could see a normal sized person a mile away, you probably couldn’t tell if he or she suddenly grew an inch taller. But you could see if he or she suddenly doubled in size or grew 10 or 1,000 times larger.
The real numbers of autism are so close to what they have always been that the experts can’t tell if they really have increased.
The numbers used to make it look like there’s an “epidemic” are badly and very obviously twisted. A child can understand the problems with the IDEA data and the CDDS data and why we know that they show no “epidemic”.
For instance that the “epidemic” is mostly found in southern California in the DDS data, and is strongly correlated with the wealthy sections of SoCal.
For instance, as the numbers of “autism” have risen in the IDEA data, the numbers of “MR” and “SLD” have dropped to more than cover the increase in “autism”.
People don’t have a leg to stand on if they insist on the “epidemic”. Even ASA president Lee Grossman couldn’t defend it when put on spot. He knows, it seems, that there hasn’t been an epidemic.
He also says he wants to see autism accepted and cherished as a normal part of humanity.
Thanks Ms. Clark. And to be clear, when I say there hasn’t been an autism epidemic, I mean there hasn’t been what they call a “tsunami”, a 10x increase or whatever. This much is quite clear. But I don’t have precise numbers. I can’t tell you if there has been a 1.3 factor increase or decrease, for example.
There’s no real evidence of a true increase, is the key part. If Harold or someone else feel there is evidence of a true increase, please post it so we can discuss it.(Harold specifically seems to believe that if the increase in diagnoses is big enough, there just needs to be a real increase somewhere in there – maybe he can explain the reasoning that leads to that conclusion).
The PSC lawyer does say that there is an epidemic… “The epidemic is real”.
He claims that people couldn’t have overlooked “hundreds and hundreds” or regressive cases in the last 20 years.
Hundreds?
He says that there is no change in the criteria for ‘regressive’ autism.
Now, one of the real strange things, he claims that the regressive cases have stayed at the same percentage of the total number of the autism count.
If the number of regressive autism is too small to see in an epidemiological study, how can you say that the fraction of the total has stayed the same.
This leaves the HUGE question–what has caused the total to increase? Why would it change at the exact same rate as the ‘clearly regressive’ type? This makes no sense. Let’s say that improved detection is behind the non regressive type and TCV’s are behind the regressive type. Why would they increase at the same rate?
Of course, another big question–why would the ‘clearly regressive’ increase at all? Shouldn’t it have jumped and dropped with each change in the thimerosal load from the vaccine schedule?
The logic is not working.
He says that there is no change in the criteria for ‘regressive’ autism.
Which is a strange thing to say, since under Kanner’s criteria regressive autism could never have been thought of as “autism”. Quoting from Kanner (1943):
“The outstanding, “pathognomonic,” fundamental disorder is the children’s inability to relate themselves in the ordinary way to people and situations from the begining of life. Their parents referred to them as having always been “sel-sufficient”; “like in a shell”; “happiest when left alone”; “acting as if people weren’t there”; “perfectly oblivious to everything about him”; “giving the impression of silent wisdom”; “failing to develop the usual amount of social awareness”;“acting almost as hypnotized.” This is not, as in schizophrenic children or adults, a departure from an initially present relationship; it is not a “withdrawal” from formerly existing participation.”
(Emphasis mine)
Ms. Clark – “If you add an ABA or Floortime therapist to a town, will there be a sudden outbreak of autistic children?”
I love this!