2011 to 2022 Autism "surge"
The key to understanding autism epidemiology is to examine the data by birth year. Your year of birth is one of the few things about you that can never change. Your age, on the other hand, always increases by one every year.
When you compare people who were a certain age in different study years, you are comparing different people born in different years. Many papers show data organized by study year while few explicitly show birth year. You can easily convert one to the other: study year minus age equals birth year. For example, children who were eight years old in 2020 were born in 2012. This JAMApaper’s reported data are in terms of age, not birth year. But we can easily convert it to birth year.
To understand what the data has to say, we have to know what the numbers mean. Is it about rates that people were diagnosed? Or is it about prevalence—that is, how many autistic people there are at a given time? Those are different things. The paper uses both “diagnosis rates” and “prevalence.”
While the correct interpretation is not obvious, Grosvenor confirmed my guess. In fact, the data shows the proportions of members of the participating health networks who had an autism or ASD diagnostic code in their electronic health records in each study year. A diagnostic code does not mean that someone was diagnosed recently. It doesn’t necessarily mean they were ever diagnosed. Doctors treating patients decide what diagnostic codes to put in patients’ records. An autism or ASD diagnostic code might indicate that the patient was diagnosed at some point in the past, but that’s not entirely correct. We can treat it like prevalence.
The 26-34 group in the 2011 data was born in 1976 through 1984, while the 26-34 group in the 2022 data was born in 1987 through 1995. (In this paper’s data, the ages refer to the year before each study year.) Greater diagnosed prevalence in the later-born group vs. the earlier one could be due simply to greater prevalence among the later group.
But does the later-born group actually display a greater prevalence? We can answer that by looking more closely at the data.
The paper’s data has birth year prevalence information, but it takes a bit of effort to dig up. This JAMA paper’s eTable 7 gives the proportions of autistic patients (those with diagnostic codes) for each study year grouped into ranges of ages. I used an Excel spreadsheet to study the diagnostic code prevalence by individual birth years. The result is not as precise as we’d like, because of the age grouping, but it is still quite informative.
The following graph shows the birth year prevalence for birth years 1976 through 1995, encompassing both the earlier and later groups mentioned above. As I said, it’s not exactly prevalence but it’s the closest we can get with this data.
As you can see, there was a dramatic exponential increase in birth year prevalence: 12.3 percent per year. Note that the graph looks lumpy because the data is grouped into ranges of years.
The later-born group, born in 1987–1995, has an average birth year prevalence that is 3.82 times that of the earlier group born in 1976–1984. So, most, or possibly all, of the increase found between those two groups of adults likely came from the increasing birth year prevalence. That shows that the “recently diagnosed adults” interpretation is not correct.
Other data sources consistently show that as people from each birth year age, more are diagnosed, and this trend is similar for all birth years. So while the health systems may have diagnosed some members as adults—we can’t tell from this data—that is not something new. It has been going on for decades.
We can also examine the trend in birth year prevalence for all birth years.
This shows an increase of 7 percent per year of birth, which strikes me as fairly significant. It's almost the same increase as in the set of CDC autism reports on children born 8 years before each study year. The CDC reports show an increase of 7.4 percent per year from birth years 1992 through 2012.
Two scientific papers in the last few years purport to show there are vast numbers of undiagnosed adults. Both rely on the assumption that birth year prevalence has been constant all along.
I argue that both the data in this JAMA paper and the CDC reports contradict that assumption, meaning that there are relatively few undiagnosed adults now but there will be many more autistic adults in the future as the younger autistic people age. That says a lot about where public policy and research should focus.
A problem with this whole idea of "birth year prevalence": It assumes that all actually autistic people get diagnosed eventually (or at least sufficiently suspected, at some point, for their doctor to use the relevant ICD code).
But a lot of older, probably-autistic adults never do seek a diagnosis. For many of us, seeking a diagnosis is just not worth the hassle and money, due to the lack of services for autistic adults. And it seems to me that the older someone is before it finally occurs to them that they might be autistic, the less likely it is to seem worthwhile to seek a diagnosis.
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The key to understanding autism epidemiology is to examine the data by birth year. Your year of birth is one of the few things about you that can never change. Your age, on the other hand, always increases by one every year.
When you compare people who were a certain age in different study years, you are comparing different people born in different years. Many papers show data organized by study year while few explicitly show birth year. You can easily convert one to the other: study year minus age equals birth year. For example, children who were eight years old in 2020 were born in 2012. This JAMApaper’s reported data are in terms of age, not birth year. But we can easily convert it to birth year.
To understand what the data has to say, we have to know what the numbers mean. Is it about rates that people were diagnosed? Or is it about prevalence—that is, how many autistic people there are at a given time? Those are different things. The paper uses both “diagnosis rates” and “prevalence.”
While the correct interpretation is not obvious, Grosvenor confirmed my guess. In fact, the data shows the proportions of members of the participating health networks who had an autism or ASD diagnostic code in their electronic health records in each study year. A diagnostic code does not mean that someone was diagnosed recently. It doesn’t necessarily mean they were ever diagnosed. Doctors treating patients decide what diagnostic codes to put in patients’ records. An autism or ASD diagnostic code might indicate that the patient was diagnosed at some point in the past, but that’s not entirely correct. We can treat it like prevalence.
The 26-34 group in the 2011 data was born in 1976 through 1984, while the 26-34 group in the 2022 data was born in 1987 through 1995. (In this paper’s data, the ages refer to the year before each study year.) Greater diagnosed prevalence in the later-born group vs. the earlier one could be due simply to greater prevalence among the later group.
But does the later-born group actually display a greater prevalence? We can answer that by looking more closely at the data.
The paper’s data has birth year prevalence information, but it takes a bit of effort to dig up. This JAMA paper’s eTable 7 gives the proportions of autistic patients (those with diagnostic codes) for each study year grouped into ranges of ages. I used an Excel spreadsheet to study the diagnostic code prevalence by individual birth years. The result is not as precise as we’d like, because of the age grouping, but it is still quite informative.
The following graph shows the birth year prevalence for birth years 1976 through 1995, encompassing both the earlier and later groups mentioned above. As I said, it’s not exactly prevalence but it’s the closest we can get with this data.
As you can see, there was a dramatic exponential increase in birth year prevalence: 12.3 percent per year. Note that the graph looks lumpy because the data is grouped into ranges of years.
The later-born group, born in 1987–1995, has an average birth year prevalence that is 3.82 times that of the earlier group born in 1976–1984. So, most, or possibly all, of the increase found between those two groups of adults likely came from the increasing birth year prevalence. That shows that the “recently diagnosed adults” interpretation is not correct.
Other data sources consistently show that as people from each birth year age, more are diagnosed, and this trend is similar for all birth years. So while the health systems may have diagnosed some members as adults—we can’t tell from this data—that is not something new. It has been going on for decades.
We can also examine the trend in birth year prevalence for all birth years.
This shows an increase of 7 percent per year of birth, which strikes me as fairly significant. It's almost the same increase as in the set of CDC autism reports on children born 8 years before each study year. The CDC reports show an increase of 7.4 percent per year from birth years 1992 through 2012.
Two scientific papers in the last few years purport to show there are vast numbers of undiagnosed adults. Both rely on the assumption that birth year prevalence has been constant all along.
I argue that both the data in this JAMA paper and the CDC reports contradict that assumption, meaning that there are relatively few undiagnosed adults now but there will be many more autistic adults in the future as the younger autistic people age. That says a lot about where public policy and research should focus.
A problem with this whole idea of "birth year prevalence": It assumes that all actually autistic people get diagnosed eventually (or at least sufficiently suspected, at some point, for their doctor to use the relevant ICD code).
But a lot of older, probably-autistic adults never do seek a diagnosis. For many of us, seeking a diagnosis is just not worth the hassle and money, due to the lack of services for autistic adults. And it seems to me that the older someone is before it finally occurs to them that they might be autistic, the less likely it is to seem worthwhile to seek a diagnosis.
Never mind not seeking a diagnosis, not even having a clue one is autistic until the day one dies.
What I noted earlier still holds true for the demographics he studied. Formal and informal diagnostic criteria changed a lot over the years. In addition Autism then as now is still diagnosed via observation, self report, and parental or sibling report. Subjective. Comparing data with such variables is unscientific.
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Professionally Identified and joined WP August 26, 2013
DSM 5: Autism Spectrum Disorder, DSM IV: Aspergers Moderate Severity
“My autism is not a superpower. It also isn’t some kind of god-forsaken, endless fountain of suffering inflicted on my family. It’s just part of who I am as a person”. - Sara Luterman
But a lot of older, probably-autistic adults never do seek a diagnosis. For many of us, seeking a diagnosis is just not worth the hassle and money, due to the lack of services for autistic adults. And it seems to me that the older someone is before it finally occurs to them that they might be autistic, the less likely it is to seem worthwhile to seek a diagnosis.
Just like Democracy birth year prevalence is the worst choice except for all of the other ones. It's kind of unfortunate that it's somewhat easier to identify false positives than false negatives and if you're talking about people who weren't even screened, it gets even trickier.
Autism diagnosis should be done at 8 and 18.
Firstly it would cover many Aspies who are diagnosed as teens (particularly girls), i don't even think these are covered in official diagnosis figures? which are at 8.
Secondly it would give the true reading of ID in autism since at 8 years old 25% are in borderline ID. Studies have shown this figure splits 50:50 by age 18.
But we still get the lie by omission that around 33% of autistic people are ID. The true figure is close to 50%.
Maybe RFK will shake things up who knows
_________________
"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends upon the unreasonable man."
- George Bernie Shaw
Firstly it would cover many Aspies who are diagnosed as teens (particularly girls), i don't even think these are covered in official diagnosis figures? which are at 8.
Secondly it would give the true reading of ID in autism since at 8 years old 25% are in borderline ID. Studies have shown this figure splits 50:50 by age 18.
But we still get the lie by omission that around 33% of autistic people are ID. The true figure is close to 50%.
Maybe RFK will shake things up who knows
Ideally, diagnoses would be done on a schedule like that, unfortunately, that isn't always the way it is for various reasons. The point of birth year prevalance is to protect against issues like in 2020 where it was incredibly hard to get any sort of in person evaluations and the couple years afterwards when social skills were somewhat delayed due to a lack of social interaction. Going by birth year when tabulating the figures helps to reduce the issues. Individuals diagnosed later should be included or excluded as appropriate to the given use of the statistics. Sometimes including the broader population makes sense, and sometimes it doesn't.
As far as the ID component goes, from what I've seen, there does seem to be a weird bimodal distribution where there's potentially two different distributions sitting on top of each other. Not including AS with ASD would probably have helped a lot in terms of clarity of what we're dealing with in terms of ASD. It's poor form that it was put into the DSM IV and then removed in the DSM 5 in spite of the first studies on masking not showing up until midway between the two editions being published and there being relatively little research into whether or not AS was autistic enough to justify lumping it in, or if it's more schizophrenic and belonged lumped with ScPD. As the two terms have a fairly long history of being used almost interchangeably going back well before AS was added to the DSM.
I'm not personally the sort that thinks that being towards the higher masking end makes folks better people, but there are good reasons to rethink the lumping everybody into the same spectrum, especially when a bunch of the higher needs folks are no longer diagnosable.
Its certainly a strange way of doing things, on the one hand they class Aspergers as ASD, but if your not diagnosed by 8 then you wont show up in official figures on autism prevalence.
But most people with Aspergers wont be diagnosed until after 8, usually teenagers, and they wont be officially picked up.
So they say ASD is around 1 in 36? but the real figure including Asperger's is a lot more, a hell of a lot more....
_________________
"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends upon the unreasonable man."
- George Bernie Shaw
So after trying to source reasoning in the why and wherefore ....personal opinion follows :
After knowing my own birth family. And how degrees of autism were dispersed unevenly in my siblings.
And meeting other autists in person , kinda leaning towards the idea ,of Mothers that have chikdren when they are older,and some women put off childbirth till later as the years have passed. and secondly . The amount of stressors mentally have been more serious for women ,last many years. Single moms having more than she should have to handle. Think these things can contribute to causes of newborn Autism...to some degree or another ..
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Diagnosed hfa
Loves velcro,
I don't wish I was diagnosed in childhood, because of the stigma. I wish I got accomodations at school though. It seems like everyone except me and a couple of others got them, including good students: dyslexia, dysorthographia, dyscalculia, dysgraphia. None of those would have been of use for me, but I'm sure the overall experience at school could have been made less straining. I'm very good at mathematics, finish tests before time and often the fastest, spelling isn't a problem for me, nor is handwriting (... at least not a major problem, my handwriting isn't pretty, but it's readable). I don't know what kind of accomodations would be useful for me unfortunately, I think it's still not a solved issue, I struggle with overstimulation a lot, and with being plain exhausted despite doing less than in the past. A regular lifestyle with going to school everyday and not having to socialise most of the time, just doing my thing, served me better. School could have been easier, but it was easier than what I have now. All the help was denied, because I was a good student and had all the skills and the such. No matter I got sick all the time and was exhausted, stressed and hence not functioning well in other areas... who cares, as long as you have straight As? To sum up, I wish I was diagnosed, but with something less stigmatising than autism/Asperger's. It was a blow to my confidence even as an adult, but let's be honest, adults are more emotiononally resilient and have a more stable self-esteem.
Its certainly a strange way of doing things, on the one hand they class Aspergers as ASD, but if your not diagnosed by 8 then you wont show up in official figures on autism prevalence.
But most people with Aspergers wont be diagnosed until after 8, usually teenagers, and they wont be officially picked up.
So they say ASD is around 1 in 36? but the real figure including Asperger's is a lot more, a hell of a lot more....
For better or for worse, there's a sort of weird status that has become attached to being autistic or ADHD versus other developmental disorders. ADHD does, to some extent, have a few inherent bits about it that lends itself to that, but I have the feeling that if they hadn't reflexively drawn the lines with so little care, that ASD wouldn't have the sort of glow that it does. It's a diagnosis that's probably not a real thing the way that some other diagnoses are in the sense that there's way too little uniformity in terms of what it does and the impact that it has on people's lives. And, there's a pretty decent argument that they shouldn't have crammed all those folks together as it's made it a lot easier to create new misdiagnoses as a result. Sure, people could fall between the cracks, but if they had a legitimate developmental condition there probably was an option to cover it. Now, there may not be any diagnosis available at all.
The whole business of them creating Social Pragmatic Communication Disorder, was somewhat problematic as even around here, I haven't noticed anybody talking about it. I do think that some of the people self-diagnosing autistic are probably more appropriately classified as such. But, with so little effort made to address the issue of people that have their traits more internally focused, it can be really tough to tell internally focused traits with traits not being there at all.
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