Friday, May 05, 2006

Autism "Missed" Often, Even Today

Blaxill (2002) introduced the notion that there is no "hidden horde" of adult autistics. Blaxill's letter was already dissected by Kathleen Seidel in Reflections on the "Hidden Horde". Autism bloggers might also recall Mike Stanton's possible finding of a "hidden horde" in the UK.

What I want to focus on here is a specific type of claim put forth by Blaxill:

Nylander and Gillberg screened adult psychiatric outpatients for evidence of undiagnosed autistic spectrum disorders. This population had not been screened for autism previously. The authors hypothesized that they would find high rates of undiagnosed autism. The screening procedure located 19 adults with autistic spectrum disorders who had not received a prior diagnosis. However, the prevalence in this group was only 2.7 per 10000, a finding that provides little support for a hidden horde hypothesis. The authors note this point reluctantly, claiming that the observed prevalences "should be regarded as an absolute minimum."


Blaxill refers to Nylander & Gillberg (2001). The authors correctly qualify the "absolute minimum prevalence". Every autistic adult would not be expected to be a psychiatric out-patient, as defined in this study. But we can extrapolate. The authors find that 1.44% of these patients had "definite ASD". Now consider that the prevalence of psychiatric disorder in adults varies considerably between 10% and 20%. This would seem to result in a prevalence of 14 to 29 in 10,000, from this population alone.

Note also how Blaxill fails to mention that 89.5% of all autistics found by Nylander & Gillberg were previously "missed".

Scharin & Hellstrom (2004) have found that adult psychiatry does not recognize disorders in the patient population by the frequency the disorders presumably appear.

Consider also Stahlberg et al (2004), which finds that 30% of adult patients with ADHD had comorbid ASD. As of 2006, the prevalence of ADHD in adults in the US is 4.2% [ref]. If Stahlberg's sample is representative, the resulting prevalence of ASD is 126 in 10,000, from this population alone. This is clearly a scandalous result.

Bajerot et al (2001) found that 20% of OCD subjects had "autistic traits" and suggested that OCD is related to HFA and Asperger's. The prevalence of OCD in adults is around 4% [ref]. Putting these numbers together we come up with an ASD prevalence of around 80 in 10,000, from this population alone.

So far we have not even considered the institutionalized population. An early finding by Shah et al (1982) was that 38% of the adult population in a mental handicap hospital had behaviors consistent with autism. A similar result was obtained by La Malfa et al (2004) in an Italian population with intellectual disabilities. Before the study, only 7.8% were recognized as having PDD. Prevalence in the population with intellectual disabilities varies widely from 3% to 50%, according to de Bildt et al (2005). Considering that the prevalence of mental retardation is about 1%, a 38% proportion of ASD in this population would result in an ASD-MR prevalence of 38 in 10,000.

Autism is missed frequently in many populations. For example, among those with bipolar disorder, the prevalence of ASD is anywhere from 8% to 62% [ref]. It is about 32% in the population with epilepsy [ref]. (The prevalence of epilepsy is 0.5% to 1%). ASD affects about two thirds of people with Tourette Disorder [ref]. It is found in anywhere from 10% to 14% of the population with learning disabilities [ref][ref]. (The prevalence of learning disability is around 5% or 6%).

To contrast, note that the current California DDS recognition of autism in the population with epilepsy is about 4%, and 7% in the population with mental retardation. In other words, the prevalence of autism in California has nowhere to go but up.

No studies to date have looked at the total population prevalence of ASD in adults, but one comes close. Baron-Cohen et al (2001) assessed a control group with the Autism-Spectrum Quotient (AQ). It found that 2% scored higher than 32. The study mentions that after an interview, 7 of 11 previously undiagnosed high-scorers met threshold criteria for a DSM-IV diagnosis. It is also known that 20% of autistics are missed by the AQ. Putting these numbers together we come up with a prevalence of 159 in 10,000 for the non-institutionalized population of adults. The 2% finding should be taken with a grain of salt, as the control group size is only 174. But note the study was replicated in Japan by Kurita et al (2005) who found the proportion of high scorers to be 3% in a control group of 215 individuals.

[Errata: The best replication of Baron-Cohen et al (2001) is actually Wakabayashi et al (2004), with a control group of "normal adults" of size 194 and another control group of university students of size 1050. They found that 3% of individuals in both control groups scored more than 33.]

Baron-Cohen et al (2001) also found that scientists (including mathematicians) scored significantly higher than controls, as did the group of Mathematics Olympiad winners. I wonder if these qualify as "geeks who got lucky", which is the other theory Blaxill is fond of.

If these prevalence numbers in adults seem high, consider Posserud et al (2006) who found that 2.7% of children in the 7-9 cohort were high scorers in the ASSQ. This study also documents what I interpret as parent unwillingness to have a child labeled autistic.

So what is the true prevalence of ASD, after all relevant populations are screened? Is it 200 in 10,000 perhaps? Frankly, this question in unanswerable. A diagnosis of autism, to date, is inherently subjective. It's not only the criteria that matters, but also how the evaluator understands and interprets the criteria. Even when more systematic instruments are used, scoring each item is a subjective exercise, and threshold scores are either arbitrary or selected from a prior subjective basis. To take an example, Posserud el al (2006) finds that 2.7% of children score in the 97.3 percentile of the ASSQ. He could very well find that 5% of children are in the 95 percentile. Why is one boundary better than the other?

Timimi (2004) makes a good case about the subjectivity of an autism diagnosis. Other parents might also find some of Timimi's remarks encouraging:

In my clinical practice I often come across children and adolescents who are labeled autistic. When I focus on their abilities I often find much about them that does not fit the autistic discourse. Once I reopen the question of diagnosis many adolescents ask me to officially "undiagnose" them, which their parents are usually very pleased about.


Summary

Blaxill should recognize that his "hidden horde" device is of little value at this point. The prevalence of autism in adults is likely about as high as that found in children. Autism is apparently often "missed" in many populations and is only identified after exhaustive screening. Finally, it is important to realize that a diagnosis of autism is not medical, but subjective.

Joseph, father of autistic child

32 comments:

  1. Hi Joseph
    Autism is known in reported scientific literature to evolve in teens and to reach adulthood with an individual path.
    The kind of higher awareness to the condition-in such amount that the numbers increase to 3 % of the overall population-maximum- is the count of the results of an incredible number of factors acting at an individual level.
    The environmental factors are part of this. I think that the problem with the hidden horde is that it is very difficult to me to know -if causes are not known- about how supposedly autistic people in the past could fit the autism diagnosis today, why they were missed as children.
    If we suppose for a moment that introduction of vaccines/antibiotics/other chemicals took some impact in genetically susceptible individuals- and the impact has been worse generation after generation- we have no data about the impact of the crowded schedule of vaccination from the 1990´s up to the 2010/2020- with children vaccinated with those schedule to become adults.
    María Luján

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  2. Joseph,
    You've done a great deal of good research on this one! I am wonder if you came across another issue that may affect these numbers. In order to be diagnosed with autism the person has to have the symptoms before the age of 3. For many adults, the parents may no longer be available to confirm that this is true. I don't think it is possible to officially diagnose an adult with no remaining parents with autism.

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  3. That's a good point Jennifer. I know I had all of the signs of being autistic before I was three and at least several years beyond.

    There is no doubt I would have received a diagnosis of ASD or PDD today but back then I was just 'difficult' and odd. My parents didn't have a label and they didn't need one. I'm sure I would be 'missed' once I was a little older and once I learned how to act more like my peers.

    So I think more kids are being diagnosed these days and I think many are missed.

    Aside from diagnostic criteria used by professionals, parents and educators are more likely to seek a diagnosis these days.

    Yes it's hard to miss many kids with more obvious behaviors or delays but I've also encountered several children that were described as severe or moderately severe by their parents and they seemed to be very high functioning when I met them in person.

    These are the kids who may seem very autistic on a bad day or in early videos and these are the kids who make great strides and are sometimes said to recover. I have yet to see or meet a severely autistic child who appears typical after a few years of biomedical or behavioral interventions.

    Not saying it hasn't happened but it must be rare.

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  4. Hi María,

    The environmental factors are part of this. I think that the problem with the hidden horde is that it is very difficult to me to know -if causes are not known- about how supposedly autistic people in the past could fit the autism diagnosis today, why they were missed as children.

    There are 2 kinds of "missed". One is like what happened to Camille or to me. We really were "missed". I was obviously hyperlexic and not one person pointed this out at the time. The other kind is a misdiagnosis. I have a brother who was diagnosed as ADD in the 1980s. He now believes he's Aspie (after I found I am).

    Nylander & Gillberg is important in this regard. They found a sample of "definite autistics", 90% of whom had previously been missed. Extrapolate this to a prevalence of 4-10 in 10,000 before the 1990s. You end up with 40 to 100 in 10,000 who should have been diagnosed then.

    If we suppose for a moment that introduction of vaccines/antibiotics/other chemicals took some impact in genetically susceptible individuals- and the impact has been worse generation after generation- we have no data about the impact of the crowded schedule of vaccination from the 1990´s up to the 2010/2020- with children vaccinated with those schedule to become adults.

    No, but we know that 2.7% of 7-9 y/o kids are high scorers in the ASSQ in 2006. And we know that 2%-3% of adults are high scorers in the AQ Test between 2001-2005. (This is in different countries). I find it tough to argue that anything remarkable has happened in the past generation at least.

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  5. Hi Joseph
    thank you. I have found myself also probably as diagnosed with HD in my childhood,and today probably would be diagnosed with ( with a touch of AD following my son´s neurologist). My husband is a non-diagnosed mild Asperger. What I try to say is that the evolution of ASD from childhood to adulthood makes change in the medical condition, for example from ASD to ADHD or to HD or to Asperger. Therefore it is very difficult for me to know
    a-if the diagnosis of ASD is "maintained " in adulthood
    b-if at an individual level there is a "shifting" to other diagnosis in the spectrum ( milder forms of ASD)
    c-how to know when only numbers are analyzed all this individual situations, specially considering different approaches (behavioral or biomedical).
    I am open to the idea of that autistics (diagnosed today under DSMIV) were always present, since several generations. What I am open also is that the introduction of new stressors the last 100 years triggered new symptoms/comorbilities concomitant-resulting of the interaction of these genetics with environmental insult.
    You say
    I find it tough to argue that anything remarkable has happened in the past generation at least.

    We are having a population of 3 % based on all people. BUT we have not precise data about how relative presentation of the autism today will be in adulthood for the children diagnosed today compared to how adults today have symptoms that are considered in the spectrum, because the environmetal insult has been different.
    I feel that the current situation of the use of DSMIV can detect a wide pool of population with autistic traits, from very mild-and including AD- to very severe. What we can not assure is that the children of the last 20 years will have the development as population of the children of 40 years ago-in terms of "shifting to milder form because of development".
    I hope I am clear about what I am concerned about that for me the current analysis is not taking in consideration.
    My point is if a child was "missed" 30-40 years ago as a child was because his/her symptoms were not so severe, even when symptoms were present. The CDC report of MAy 5 presents that 58.2 % of the diagnosed children have high difficulties and 24.4 % have moderate difficulties. I understand the limitations of these data but the report is considered trustable in the sense of overall result.
    My point is what if what was missed yesterday - myself included- because of severity of symptoms-that were milder that today in terms of lack of speech, stimming, tantrums-now is not missed because the symptoms are much more severe in childhood-beyond all the problems with ADHD and more awareness of the condition??
    Thank you in advance
    MAría Luján

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  6. Hi Joseph
    A clarification about my last point
    BUT the genetic pool was always the same and the prediposition was always present in the 3 % of the general population in the last generations.
    María Luján

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  7. I just want to make the point that not all of those who were "missed" were high functioning. My husband has a cousin, who is now in her late 40's, who was placed in an institution at the age of 4. She was diagnosed with autism at some point, but her original diagnosis was MR.

    I think for many of the more severely affected, there probably was an attitude that it didn't really matter what the diagnosis was, because there wasn't anything to do except put these individuals in institutions. Treatment, If you could call it that, was the same no matter the diagnosis. When my mother-in-law told me about the situation with my husband's cousin, she basically said that there was nothing else her parents could do with her since she was too disruptive at home. Remember, at that time you couldn't send a child like that to public school, and most people didn't have money for a private school or therapy. It was definitely a very different attitude at that time.

    My MIL recently told me about an even older family member, my MIL's cousin, who is now in her 60's, who has MR and has always lived with family. I asked if anyone knew why she was MR(I was wondering if she also might be autistic), but my MIL said "I don't know, she's just retarded I guess." I'm guessing this older woman has never been "counted" in any sort of way in numbers of individuals with devlopmental disabilities.

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  8. Hi Jennifer,

    You've done a great deal of good research on this one! I am wonder if you came across another issue that may affect these numbers. In order to be diagnosed with autism the person has to have the symptoms before the age of 3. For many adults, the parents may no longer be available to confirm that this is true. I don't think it is possible to officially diagnose an adult with no remaining parents with autism.

    That might be a problem in diagnosing Autistic Disorder. But I bet most new adult autistics seek a diagnosis of Asperger's. In reality, pure DSM-IV or ICD-10 Asperger's appears to be as rare as classic Kanner autism. See Leekham et al.

    I'd imagine most adults do know if they were late-talkers. I know my dad did not speak until he was 4, even though my grandma is not around anymore.

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  9. On late talkers - there may be a few around who don't know.

    My father-in-law didn't know until my mother-in-law mentioned her concerns about my son not speaking to the older of his two younger sisters. Her mother had told her (but not him, or his wife) that he didn't speak until after his third birthday. So if it weren't for his grandson, he wouldn't have known.

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  10. We can account for all the adult autistics fairly easily...

    Take the base rate for the past 400 years... as 1 in 150.

    Some autistic kids die, that's very sad, but some normal kids die, too.

    The ones who are so disruptive, unable to "fit in" get extreme treatments and extreme diagnoses (demon possessed, childhood schizophrenia, MR... depending on the time period and who was doing the diagnosing) the ones who are closer to normal get no diagnosis (Frank Klein was totally autistic as a small child and no one ever diagnosed him until he was in his 30's, his mom could confirm what he was like, echolalia and everything) Kids who today are the majority of those getting diagnosed with "autism" are more technically PDD,nos... those kids just got pushed through the school system maybe with little bits of help from speech therapists... they just struggled along, like me. There used to be a dx called, "minimal brain dysfunction" where are all those kids now??? They are ADHD or PDD,nos kids.

    Before a Tourette's kid was just a Tourette's kid, now he's likely to have a dual dx, Tourette's/Aspergers. Same with OCD, how easy would it be to call a PDD,nos kid and OCD kid? Very easy.

    How about dyslexia? If the kid is like Aspergers but can't read, he'll just get a dyslexia lable. I know one like that, got AS dx as a teen.

    How about "emotionally disturbed"? How easy is it to call an ASD kid "emotionally disturbed"? Very easy.

    The kids who were on the edges, like Not Mercury as a 10 year old... like me.. no one bothered with a diagnosis of any kind. I was 43 years old when I got an AS dx!!

    There hasn't been anything like an increase in autism, and there's no evidence for an increase in severity. The majority of the kids are not any more severe than their parents at the same age. The parents don't usually like to talk about their history.

    Various professional people have contacted me privately by email and said, "You know, don't tell anyone, but I was a very weird kid.. I was in special education until I was 8... I was labelled retarded..."

    I know a medical doctor who was labelled as retarded as a child. He ain't retarded. He's brilliant.

    30 years ago the dysfunctional kids were almost never in the public schools. They were sent to institutions. My mother in law and her brother were both in an institution in Idaho for a while as children.

    I want to scream when I hear people like David stinking Kirby say, "there were no autistic kids in my school when I was growing up".... No duh, idiot!!! (excuse my language).

    Some of the autistics were killed in those institutions. They were drugged with first generation drugs, dangerous stuff, if the current stuff is bad, how'd you like to be an autistic in an institution in 1960? They died. Others have killed themselves.
    http://www.sentex.net/~nexus23/po_miss.jpg
    Look at that poster and think about it.

    People who were more disabled as children and have less disabled or normal kids don't go around talking about their childhoods. If I had only had one child, my NT child, then I probably would never have figured out that I have AS, or that my ex-husband's family, going back generations has ASD people in it. I knew they were weird, or maybe crazy, but I had no other category to put them in.

    The logic of the genetics of autism makes it necessary to think that the nature of autism has been pretty stable over the generations.

    It's just that it was called something else in the past or not called anything at all.

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  11. I have found myself also probably as diagnosed with HD in my childhood,and today probably would be diagnosed with ( with a touch of AD following my son´s neurologist). My husband is a non-diagnosed mild Asperger.

    No offense María, but you seem to be a walking example of assortative mating. This also applies to me, as my father-in-law is clearly Aspie. If I had another son who turned out to be NT, I'd conclude that the hospital accidentally switched babies.

    What I try to say is that the evolution of ASD from childhood to adulthood makes change in the medical condition, for example from ASD to ADHD or to HD or to Asperger.

    This could explain a bit of a drop in prevalence for older cohorts. If you look at graphs of prevalence by birth year cohort there are some indications that a small portion of teenagers (at 15 or so) lose the diagnosis. But this appears to be minimal. (These graphs also suggest that no popular treatment for autism is effective).

    I feel that the current situation of the use of DSMIV can detect a wide pool of population with autistic traits, from very mild-and including AD- to very severe. What we can not assure is that the children of the last 20 years will have the development as population of the children of 40 years ago-in terms of "shifting to milder form because of development".

    What I would point out is that human behavior is always a continuum - a spectrum. It's impossible for Kanner autism to have existed without milder forms. Also, milder forms are necessarily more prevalent (think of a normal distribution graph).

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  12. Hi Joseph
    Do not worry, I do not feel offended. Imagine that I am hyperactive -productive- and my husband is very calm and quiet. We are very different in personality, even when I see ASD traits in both.
    As you say, milder forms of autism can be very variable and touch the range of "normality" because of the spectrum of human behavior. This fact is why I think that the analysis is so complex, because there are 40 (+ unknown) variables to consider, including the impact of milder forms and how severe ones can become milder ones with development.
    María Luján

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  13. Hi Joseph,

    This is an interesting analysis. It could certainly account for some of the missing ASD adults. I would suggest though that some of the findings are directionally correct but potentially overstated, especially those without any link between degree of severity and potential towards a link with ASD, or those from which you extrapolate rates identified in children to adults (I believe the point of the exercise was to prove them, not extrapolate them):

    1. Nylander & Gillberg (2001) identified that 1.4% of adult psychiatric out-patients had an ASD. You then state that "Now consider that the prevalence of psychiatric disorder in adults varies considerably between 10% and 20%. This would seem to result in a prevalence of 14 to 29 in 10,000, from this population alone." Are between 10% and 20% of the adult population demonstrating psychiatric conditions severe enough to result in them becoming out-patients? I’d suggest the fact that we don’t know if the number is 10% or 20% indicates the answer is ‘no’. There may be a correlation between psychiatric disorder severity and ASD that would preclude a blanket assumption that characteristics that apply to out-patients would apply to the population of adults with a psychiatric disorder as a whole.

    2. Stahlberg et al (2004) found not that "30% of adult patients with ADHD had comorbid ASD" but that of "consecutively referred adult patients", "Thirty per cent of patients with AD/HD had comorbid ASD". Again, as above, the patients being studied had to meet the hurdle of being referred, which implies a level of severity greater than average. So again, is there a correlation between the level of severity and a finding of ASD?

    3. Bajerot et al (2001) found that 20% of OCD subjects had ‘autistic traits’, and the prevalence link suggested a rate of 4% in 18 year olds. Three points: i) what is the definition of ‘autistic trait’? Does this mean that they would qualify for an ASD diagnosis, meet at least one of the twelve conditions in category A, fall somewhere in between (and then where?), or other? ii) Is there a link between severity and autistic traits? As above, to come to the attention of the researchers the severity is presumably greater than average, unless 2 - 4% of the population is, has been, or will be treated for OCD. iii) Wikipedia suggests a prevalence of 2% in adolescents and adults, but suggests that the prevalence could be higher. I’m not sure if prevalence can change over time or is age related. If it changes with age then does ASD?

    4. De Bildt et al (2005) found estimates of 3% to 50% in their literature search, but their conclusion was that "The DSM-IV-TR prevalence (16.7%) seems to be the most reliable and well-founded estimate" of the prevalence of PDD in children and adolescents with MR – which you didn’t mention. La Malfa et al (2004) landed on 38%. At 1% of the population, I’d agree that the MR category could hide a lot of missing ASD people.

    5. Your bipolar reference to the paper on mood and anxiety disorders appears to be an evaluation of three screening questionnaires/checklists. It found that "The prevalence of those screening positive for a possible ASD on one instrument was 62% and on all three measures was 8%", leading to the final statement that "These results demonstrate a need to develop valid and reliable instruments to screen for ASDs in children presenting outside of ASD clinics." The epilepsy reference is to children, as are the Tourette syndrome reference and the learning disabilities references. All of the above mentions imply that these conditions endure in adulthood as undiagnosed autism, which may not be totally accurate. The learning disabilities example is a) also in children and b) can fit within the gap between existing rates and an assumed prevalence rate of 0.6%, since as Camille has pointed out elsewhere, no jurisdiction is yet reporting a rate of 0.6%

    6. Baron-Cohen et al (2001) showed that 2% of the controls scored 32+ (i.e. 3 people), and it is not clear in the abstract from where the 11 interview subjects were drawn (some must have come from the student or math Olympiad subjects – not necessarily a group representative of the general population). An alternate interpretation of the 20% of AS/HFA respondents ‘missed’ could also be the subjective nature of the test, which could bias the accuracy of the test upwards or downwards (although only downward bias would be evident in a test in which 100% - 58 respondents – should have been identified). Kurita et al (2005) is interesting, but the findings were that the tool had negative predictability value but not positive predictability value (i.e. it identified who to rule out, not who to include) for mild ‘high-functioning’ PDD (the abstract’s words, not mine), and the mention of 3% implies a prevalence higher than the paper’s authors might therefore accept.

    7. Posserud et al (2006)’s finding of 2.7% of children scoring high on the ASSQ indicates nothing about the ‘hidden hordes’, or even the relationship between a high score on the ASSQ and its relationship to ASD.

    8. The implication that I took from the above were that all of the groups were a) additive, and b) all were ‘new’ to the pool. I would suggest that there is considerable overlap in the groups above (which is the conclusion that some of the research authors were stating in their papers). As an illustration, how many of Baron-Cohen’s 2% will one day have a psychiatric disorder? There is also more than a little ‘known’ diagnosis in the research above, as well as ‘new’ or ‘previously missed’ diagnoses.

    9. I quite like and agree with the Timimi reference.

    Overall, I still think you can make a case to close in on a 0.6% rate in adults in the studies mentioned. But I think that some of the above draws more of a conclusion than the study authors would agree with, and I’m not sure that the children-based studies can be extrapolated to adults without evidence. Also, if you are correct in hinting that the prevalence is higher than 0.6% (e.g. 2.7%, or at least higher than commonly thought) then don’t you have to also find more adults to prove the absence of an increase?

    Finally, if the above does identify the ‘missing hordes’, it does not necessarily do so over time, but only for the last few decades. This would be enough to call into question the vaccine hypothesis, but does not rule out any longer-term increase over time. Some in your previous post seemed to be hinting acceptance that a longer term increase may in fact have occurred (e.g. changes in the chances of ‘odd’ guys reproducing in the 1960s).

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  14. Hi Ian,

    I do accept that equivalence of groups is unknown here. Psychiatric out-patients might be "more severe" than the average person diagnosed with a psychiatric disorder. What I find more significant about Nylander et al is that 90% of definite autistics were previously missed.

    And Stahlberg's ADHD patients might be more ADHD than average. In Stahlberg's case, even if the true proportion were half what he found, the resulting ASD prevalence (for this population alone) is still very high.

    In the case of OCD, if someone is already diagnosed as OCD, and is also found to have "autistic traits", what are the odds that a diagnosis of ASD is not applicable?

    Another point is that when researchers screen these populations, they seem to find a lot of ASD that was not seen before. There's a lot of overlap between psychiatric disorders. Once someone has one diagnosis, it's probably unlikely that they'll go and seek another.

    The prevalence in the MR population seems to be a crap shoot. It probably depends on who's making the evaluation more than anything else.

    And yes, I do believe DSM-IV prevalence is more than 60 in 10,000 as reported (allowing for evaluator subjectivity and all). Data based on special education enrollment is likely an underestimate. Even epidemiological studies generally start out looking at children who are "problems" in some way. I think the right way to determine total population prevalence is a screening tool like the ASSQ or the AQ applied to a fairly large representative sample of people.
    Those scoring above a threshold can be evaluated with the DSM-IV. It's also possible to make an extrapolation as to how many autistics are "missed" by the threshold. This would give a good estimate, which I believe is probably in the order of 150 in 10,000, perhaps a bit higher in children than in adults.

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  15. The best Japanese replication of Baron-Cohen's AQ test screening is actually Wakabayashi et al. I've added errata just below the pertinent paragraph.

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  16. What about Coplan's research showing that a good chunk of children with autism can be expected to lose their diagnoses as a matter of course?

    Sorry these links will be so long and ugly -http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7745522&query_hl=4&itool=pubmed_docsum
    http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10799629&query_hl=4&itool=pubmed_docsum
    http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15995041&query_hl=1&itool=pubmed_docsum

    I'm always surprised that this isn't brought up more often as a counter to the hidden horde people, but maybe it's not as strong as I think. Comment?

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  17. Hi Lisa
    One of the manuscripts you mentioned say
    although they continued to have various language disturbances, social skill deficits, and unique behavioral qualities.

    I think that, as it has been mentioned and considered, there are a lot of adults in the 30 to 75 years range, that are undiagnosed or have been diagnosed lately or can qualify for ASD under the DSMIV. My point is that the argument per se of a "hidden horde" has demonstrated to be at least not accurate considering the number of adults potentially in the spectrum and under the idea of changes in the diagnosis with development ( due to)-besides the changes in the number of children diagnosed/reported today respect to 20 years ago. However, this fact does not discard an environmental insult ( or combination of). For me the point in the analysis is to consider the AND , not the OR.
    For me the point is how the life quality can be for many of the teens or adults undiagnosed or not diagnosed in the spectrum. As a mom of an autistic boy, I am very concerned about.
    María Luján

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  18. Hi Lisa,

    Coplan even gives a formula of development:

    CARS = 37.93 - [(0.12 x age in months at first visit) + (0.23 x period)].

    Church is more surprising, as basically all the HFA kids lose the diagnosis. This is probably an artifact of the DSM-III criteria that was applied.

    It's also known, for example, that only 30% or so of ADHD kids retain the diagnosis as adults.

    I wonder if some of these kids might want to be rediagnosed or self-diagnosed as they evaluate the issue on their own, as opposed to because parents think there's a problem.

    Timimi's anecdotal account of how teenagers ask him to be undiagnosed is also interesting - first time I've come across that claim, but it matches the prevalence by birth year cohort data. I imagine it's not "cool" to be a teenager with an ASD diagnosis.

    (BTW, when I mentioned the prevalence by birth year cohort in a prior comment, I should've pointed out that drops from one line to the next could also be due to drop-outs other than loss of diagnosis).

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  19. Joseph: This is just really fascinating to me; thanks for blogging about it and thanks for the way you expound upon things in such detail in your replies.

    I have a question about "psychiatric outpatients" ... do you know what the exact definition of this is in the US? Does the definition vary according to the country (due to whatever health-system they have)?

    I am old enough to know first-hand that many people went to psychiatrists (we called them 'shrinks') in the 50s, 60s, 70s -- and paid privately; never submitted to insurance; never wanted their vistits to be "traceable". There was no need for the psychiatrist to report a dx. to anyone in any official capacity.

    Now this is where I get confused about that 10-20% range. I rather agreed with your statement/assessment here:

    "...consider that the prevalence of psychiatric disorder in adults varies considerably between 10% and 20%. This would seem to result in a prevalence of 14 to 29 in 10,000..."

    To which the Ian replies:

    Are between 10% and 20% of the adult population demonstrating psychiatric conditions severe enough to result in them becoming out-patients? I’d suggest the fact that we don’t know if the number is 10% or 20% indicates the answer is ‘no’.

    I'm not sure I understand what "severe enough to result in them becoming outpatients" actually means. Ian can you help me on this one?

    Society (in the US) has changed significantly in the last 15-20 yrs. in regards to mental health. Only a few decades back one could be fired from their employment if it were discovered they had a past psychiatric history (and this includes simply visiting a psychiatrist).

    I have written before about my family on Autism Diva's blog, but then I always go and delete my posts because I'm afraid I'm outing family members. So, I will refrain from going any further in that regard.

    I'd rather think that sociological issues had a big impact individuals not being "counted". So, Ian, I'm confused on why you deduce "no". Am I misunderstanding something in your analysis?

    Even today, one can go to, say, a 'psychologist' for talk therapy, pay out-of-pocket -- this is standard from where I sit -- this does not go to insurance. Then, one may easily get necessary meds from their family doc/GP/PCP. Would these people currently be "counted" in any capacity?

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  20. Hi Burntcherry,

    Outpatients would be those who use the services of a psychiatric hospital without staying at the hospital. (Nylander & Gillberg are in Sweden, BTW). So this does not count institutionalized psychiatric patients nor the patients of "shrinks" as you say.

    What Ian points out is that outpatients are not necessarily representative of the whole population of persons with a psychiatric disorder. They could be "more severe". There's probably a socio-economic difference between outpatients and those who use "shrinks". An argument could be made that they are "less severe" as well, or that they seek psychiatric services for specific kinds of problems.

    Nylander & Gillberg also report on "definite autistics" and it's not clear what that means.

    As to the prevalence of psychiatric disorder, it's really not well understood. Bijl says the 1-year prevalence varies from 17% (Chile) to 29.1% (U.S.). But Haro (in Spain) reports a one-year prevalence of 8.4% with a lifetime prevalence of 19.5%.

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  21. Sorry, I haven't had a chance to reply to Burntcherry til now. I think that Joseph answered the question well, but let me know if you want anything more from me on this. I would suggest also though that while attitudes may have been different in the 50s, 60s, and 70s vs. more recent times (as you suggest), the Nylander & Gillberg study was published in 2001. While I don't have the paper, the abstract sounds like the data was not historic. And as Joseph points out, the study was in Sweden, which (and I recognize this is a sterotype) has a reputation for being a bit more enlightened than the U.S. regarding a variety of social issues, potentially including those related to mental health.

    I was thinking about the prevalence shift in psychiatric disorders over time too. I'd assume that the presence of ASD makes someone more likely to be vulnerable to a psychiatric disorder rather than the other way round. On the presumption that anyone is vulnerable to a psychiatric disorder under the right circumstances (e.g. post-tramatic stress disorder, or PTSD), the event that causes PTSD would presumably not make someone also ASD, but someone who is ASD might be more vulnerable than averge to PTSD. The same might reasonably hold true for all of the little stressors in life that can build up and overwhelm people. So I would suggest that while the relationship between ASD and psychiatric disorders may not be a constant, that the two could easily have a positive covariance.

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  22. Joseph said:

    ” And yes, I do believe DSM-IV prevalence is more than 60 in 10,000 as reported (allowing for evaluator subjectivity and all)”

    and

    ” It's also possible to make an extrapolation as to how many autistics are "missed" by the threshold. This would give a good estimate, which I believe is probably in the order of 150 in 10,000, perhaps a bit higher in children than in adults.”

    María Luján said:

    ” For me the point is how the life quality can be for many of the teens or adults undiagnosed or not diagnosed in the spectrum.”

    The two combined make an interesting point. I’m not sure how many are wedded to the 0.6% number, and given that ASD is a spectrum it is possible to move the boundaries to include more of the broader autism phenotype. The issues regarding ASD for me though are closer to my interpretation of María Luján’s view (I hope I have this correct), which is concern with the impact of the issues associated with ASD (not the label itself) on the life of the individual with ASD. As I’ve said before, if autism were only a different way of thinking then for many it would not be a concern.

    I don't see any issues with autistic thought, which, interestingly enough, is not even part of the DSM-IV. From a personal perspective, when autistics discuss autistic thought processes it sounds very familiar, and a 32 on Baron-Cohen’s test appears in my rear-view mirror.

    To me the issue is not the score but the issues associated with the diagnosis, which in my daughter’s case are primarily communications (speech, overall communications, and potentially comprehension), followed by social issues that I believe are related to her communications difficulties. The other big issue are her SI difficulties, which are not part of the diagnostic criteria, but which seem to be driving the issues that are.

    From this perspective I think I agree in part with Joseph’s view that autism is (at least in part) a social construct, when it is defined as autistic thought, which can allow for a broadening of the category, but also with María Luján’s concerns for those who’s autism goes beyond a way of thinking to impact quality of life. (I apologize in advance if I’ve misinterpreted either person’s viewpoint in a way they find negative.)

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  23. Hi Ian
    You interpreted me very well. I am very open to the idea that for many people that could be potentially under DSMIV, autism can be a different way of thinking. In fact I am probably in the spectrum and I am very confortable with me. In this sense, Joseph´s numbers are understable. My point is when the particular individual combination of genetics epigenetics and environmentnal insult generates as a result a lot of concomitant comorbilities (for now I prefer this name) and how they affect the life quality. This position is far beyond the dicotomy of to cure or not cure autism. I am talking about the proper treatment under the proper testing in the adequate and trustable labs- from the clinical aspect- to all the behavioral and emotional and social and sensorial issues to be treated properly looking the individuality of the child that impact life quality. In this sense, I agree completely with you.

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  24. Ian and María,

    I think you're referring to Immune System issues.

    Before my son got diagnosed, he was getting an upper respiratory infection about once a month. The pediatrician said that wasn't anything to be alarmed about. Kids under 4 in the US get about 8 a year, he said.

    I actually got sick at about the same time my son did, like clockwork, except he was worse.

    After he got diagnosed, one of the first things we did was start the GFCF diet. And he stopped getting sick. Months passed and he wasn't getting sick. With time, we basically did not maintain the GFCF diet and found that he still wasn't getting sick all that much. In reality I think what happened was that we also took him out of the school/daycare he was attending, after he was diagnosed. I understand the main source of infections for kids is other kids.

    Two years later, he's again going to a school now (with other kids like him, where he does some speech therapy -- which I believe is useless -- but also spends much of his time doing puzzles and such as he likes). He does not get sick all that often, and I seem to get more sick than he does (at about the same time too). I believe his immune system has matured.

    My son was also born through a C-section, which I understand affects the immune system.

    If there's a way to boost kids immune systems without any adverse effects, I'm all for it. Let me know what it is.

    BTW, I'm surprised they aren't promoting Echinacea or something for autism.

    I think it's doubtful that immune system issues cause autism. I think a correlation is possible - it might just come with the territory. I'd also note that when it comes to immune system strength, there's "natural variation" on that too.

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  25. Hi Joseph
    I was not referring only to immune system issues. I think that there are a lot of concomitant comorbilities, that can include the immune system, but they are not centered in only this. Again, for me depends on the individual.
    You say
    I think it's doubtful that immune system issues cause autism.
    I do not think in immune issues per se as THE CAUSE-posnatal-, although after certain viral infections autistic traits can be present. It has been found a correlation with some viral issues- -prenatal-and autism. The combination of impact of comorbilities can be important for me.
    I understand that you are talking from your personal experience and I think is important and I respect it. But mine with my son was totally different, as I told you by e-mail, with the findings of a lot of concomitant comorbilities that needed to be treated properly- for example celiac disease and IgA total/secretory defficiency.

    María Luján

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  26. But mine with my son was totally different, as I told you by e-mail, with the findings of a lot of concomitant comorbilities that needed to be treated properly- for example celiac disease and IgA total/secretory defficiency.

    And I'm sure you're doing what you can medically to help your kid, which is good. But I'd manage my expectations regarding autism. For example, mitral valve prolapse is common in Fragile-X; it does not cause it. Seizures are common in Rett Syndrome; they do not cause it.

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  27. Hi Joseph
    You say
    But I'd manage my expectations regarding autism.

    Honestly, I do not know why every time I mention the presence of comorbilities (and I have clarified my use of this in Wade´s blog) you ( and others) consider that I am considering autism defined by the comorbilities I found. I do not consider this. What I say is that today we do not know what is the real impact of comorbilities -as a result of epigenetics and probable although not proven environmental insult on genetically susceptible individuals- and the treatment of in the life quality of autistic children/teens and adult. I did not know until I detected properly and treated adequately. I am not doing logical fallacies to consider association as caussation and others.
    This does not imply that I have expectations to "cure" autism by healing or treating celiac disease or nutritional defficiencies. Implies for me that I do not know how much of the malabsorption problems and nutritional problems related to can be affecting cognitively my son for example.
    As I told you, my expectations are that my son was born and will be genetically different. But how much of the symptomatology is related to epigenetics and environmental insult nobody can tell me today. I have a lot of comorbilities to deal with and this is what I know today. My personal analysis is respectable, especially because I am considering the anecdotic nature for science of his particular case and that I am not extrapolating his condition to ASD as a population. Even more, for me the key is to know what to search and to test properly and adequately in trustable labs.
    Sincerely

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  28. Joe;
    Perhaps you're right. Maybe there are lots of missed adult autistics. The reason they were missed is because they got less mercury than the kids today who are "train wrecks" and they are less affected by the smaller dose of poison.
    How many of those adults are over 75? You thought they would have died in institutions. Maybe they all developed Alzheimer's from being susceptible to mercury.
    Why don't we do a study on 75 year old Alzheimer's patients and question their families to see if they had some ASD symptoms before the Alzheimer's nailed them? Of course, you'd have to figure dentalamalgams into the equation.

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  29. The reason they were missed is because they got less mercury than the kids today who are "train wrecks" and they are less affected by the smaller dose of poison.

    I could start to buy that if there was evidence of increased severity. But if you look at CDDS data - easy for anyone to verify - we find that 16% of autistics in 1992 had epilepsy, 11% had profound MR, and 23% had severe behaviors. As of 2005, only 6.7% have epilepsy, only 2.4% have profound MR, and only 16.8% have severe behaviors.

    Severity is on the decline, which clearly suggests autism is simply diagnosed more often.

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  30. Addendum: Constantino (2003) is another study which supports the conclusions of this post. It finds that "Levels of severity of autistic traits at or above the previously published mean for patients with pervasive developmental disorder not otherwise specified were found in 1.4% of boys and 0.3% of girls." And concluded: "These data indicate that the social deficits characteristic of autism spectrum disorders are common. Given the continuous distribution of these traits, it may be arbitrary where cutoffs are made between research designations of being 'affected' vs 'unaffected' with a pervasive developmental disorder."

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  31. Increase in autism due to change in definition, not MMR vaccine
    "Dr Barbaresi and his colleagues looked at the incidence of autism year by year among about 36 000 children aged under 21 of the county between 1976 and 1997. Working retrospectively, the researchers correlated the definition of autism used in DSM-IV with symptoms described in medical and school records, using a list of 80 developmental, psychiatric, and neurological diagnoses."

    "They identified 124 children with autism as diagnosed by DSM-IV criteria. Most had not been diagnosed as having autism, but rather as having developmental delay, delayed speech and language development, attention deficit or hyperactivity disorder, and mental retardation. Boys outnumbered girls by more than three to one. The first symptom was noted at about 2½ by medical professionals (48.1%), school staff (30.4%), and parents or care-givers (20.9%)."

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  32. Regarding those who say that some kind of environmental factor that starting affecting kids back when today's adults were young is responsible...
    It's very tricky to estimate numbers of autistic people among cohorts who are no longer alive now, but by observing historic data it's clear that there were at least some autistic people in older times. John Langdon Down, in 1886, described two categories of 'idiocy' that overlap with autism, one called 'accidental idiocy' that sounds mostly like nonregressive autism, and 'developmental idiocy' with regression in infancy, middle childhood or adolescence, where the infant regression sounds like classic regressive autism and some of the middle childhood regression cases sound like Heller Syndrome.
    Even older, descriptions of 'changelings' include some kids who sound quite autistic, such as this boy:

    "Eight years ago [in the year 1532] at Dessau, I, Dr. Martin Luther, saw and touched a changeling. It was twelve years old, and from its eyes and the fact that it had all of its senses, one could have thought that it was a real child. It did nothing but eat; in fact, it ate enough for any four peasants or threshers. It ate, shit, and pissed, and whenever someone touched it, it cried. When bad things happened in the house, it laughed and was happy; but when things went well, it cried."
    http://www.pitt.edu/~dash/gerchange.html#LutherDessau

    I hypothesize hypersensitivity to touch, laughing when unhappy and overload at loud noises (eg parties) could explain this child's behavior. The increased eating is, according to many scholars, probably a metaphor for the burden the child presents, similar to tales of changelings living unusually long lives.

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