Sunday, April 02, 2006

Regional Differences And Quarterly Growth Due To Two Factors

I previously argued that apparent differences in the prevalence of autism across regions in the state of California must be due to group inequivalence. Given that there is a clear broadening of criteria component as time goes by, I suggested that some Regional Centers are simply behind in their knowledge of autism and catching up. But after looking at client characteristics per Regional Center, I have found that the reality is a bit more complex. Quarterly caseload growth and regional caseload differences seem to be affected by two factors that act largely independently.

Table 1: Q4 2005 Autistic Client Characteristics By Regional Center
Regional CenterAutism-Epilepsy RatioEpilepsyMRSevere BehaviorsIn MR Population
CVRC0.325.31%25.6%20.99%2.48%
SDRC0.626.82%54.73%23.42%9.26%
SARC0.855.45%17.70%14.67%5.31%
ELARC1.346.06%21.19%17.67%8.49%
WRC1.615.51%22.38%13.25%10.73%


Table 1 shows that there is inequivalence between Regional Centers, but it is not as straight forward as the inequivalence observed in the state-wide quarterly data. A pattern emerges, however, if you look at the proportion of autistics in the population with mental retardation. Except for San Diego (SDRC), which does appear to be behind in criteria, it would seem that differences in autism rates can be explained by how many clients evaluated as having mental retardation are also determined to be autistic.

In order to test this hypothesis, let us adjust the autism caseload by assuming that 7% of all clients with mental retardation are also classified as autistic (as this is roughly the state-wide average). We will then see what the proportion of MR and lack of it among autistics might be given this assumption.


Table 2: Q4 2005 Adjusted Characteristics (Theoretical)
Regional CenterAutism-Epilepsy RatioMRNo MR
CVRC0.4749.21%47.90%
SDRC0.5447.74%46.83%
SARC0.8922.10%60.96%
ELARC1.3217.82%77.29%
WRC1.4815.81%77.69%


Table 2 looks more like the state-wide time-based data, as we would expect. The consistency of these results does two things:

- It suggests that our assumption is probably valid. That is, the proportion of autistics in the MR population throws off the numbers, and differences in this proportion are apparent, not actual.

- It suggests that the proportion of autism in the non-MR population varies from region to region simply due to inequivalence, i.e. differences in criteria between regions.

New Model

These findings lead me to come up with a more specific model to explain both the explosion in diagnoses since the early 1990s and regional differences in apparent prevalence. The model involves two factors:

1) There is increasing recognition of autism in the population with MR. [This was already noted in "Like Missing a Train Wreck" - By The Numbers].

2) There is increasing recognition of autism in the population without MR.

These two factors act somewhat independently. As time goes by, both occur simultaneously. But they may vary independently from region to region. For example, San Diego (SDRC) is considerably behind the average Regional Center in Factor # 2, but is considerably ahead in Factor # 1. Fresno (CVRC) is considerably behind in both factors. West LA (WRC) is considerably ahead in both.

In retrospect, these two factors are obvious. But note that a common error is to assume that 'broadening criteria' includes only Factor # 2.

6 comments:

  1. Hi Joseph
    Thank you very much for your analysis. I always read with interest your blog, only probably have other view of the same , INCLUDING yours, but also CONSIDERING alternatives as collaborating.
    I would be glad to hear your opinion about this idea.
    Let´s go for a moment to include the possibility of, besides the widening of the awareness of ADS, a true combination of environmental factors is collaborating ( besides genetics).
    Let´s go also for a moment to agree that the same symptoms can have different collaboration for example from immune dysfunction to HM(chemical in general) poisoning because of susceptibility in combination, therefore no clear correlation can be found in ASD with NT HM poisoning/immune dysfunction because of the genetics/epigenetics difference in autistic. Same symptoms, different roots ( beyond genetics)today and several years ago.
    What if the change in trends in ASD without MR has a component of true insult of chemical nature, but without the kind of that produces MR? Imagine that MR can partially be linked to metabolic problems , genetics and immune dysfunction (viral infection included) and unknown.
    How we can discriminate if all is involved under the DSMIV? My point is that a kid with certain (same)symptoms can be today and ten years before be diagnosed with ASd and the collaborating environmental components can be different in nature.
    What do you think?
    I am not saying that I am right. I am thinking in the schizophrenia manuscript you sent me and several others I have been recently reading.
    Ma Luján

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  2. What if the change in trends in ASD without MR has a component of true insult of chemical nature, but without the kind of that produces MR?

    Let's assume that an environmental trigger is producing a kind of ASD with no seizure liability, with no MR liability, with no speech delay liability and with no special behavior liability. Wait a minute, that's not ASD, but NT :)

    I guess it's plausible, but frankly, I'd expect the data to look a lot different if any environmental trigger that worsens as time goes by were having an effect in the numbers.

    Every time I look at the numbers I find more and more indications that there is no epidemic and no real regional differences. I also find more info that explains what's going on, like the fact that recognition is also increasing within the MR population.

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  3. That is, unless the trigger is purely psychological, as suggested by autismhysteria. You wouldn't happen to allow for this kind of trigger, now would you María?

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  4. Hi Joseph
    I never consider that a personal experience must be mentioned but I feel that this last comment is not particularly fair for me Joseph. Based on personal experience, I do think that there is a strong component of environmental insult in the presentation of ASD in MY son. The experience is not extrapolable but is valid; it is not a prove but an anecdote, BUT to prove that the majority of ASD children has not a contribution of comorbilities in the presentation of autism symptomatology it must be proven that the so called comorbilities have not relationship with the gene expression and environmental combination in ASD and this has not been proven because it has not been studied because there is not an integrative study of autism TODAY.
    If you think about, I avoid terms like CAUSE or TRIGGER, because always rememeber me that there is an intention to put the root of autism beyond where the root is that is genetics. However, many times I found answers to my comments considering these terms and I am not thinking in these terms. It is like the dialogue is in terms of
    "THis is THE CAUSE or THE TRIGGER" and "THIS IS NOT the cause of the TRIGGER" What I propose is to get out of this box...
    I think that there is ALSO a component about a very negative view of autism -that I do not share-that can be collaborating in the pshychological -personal- and sociological views of what autism is and mainstreamed doctors have a lot of responsability on this.
    You say
    You wouldn't happen to allow for this kind of trigger, now would you María?

    This is not a question about what I think is happening. For me, is a question to look for what the truth is. In this sense, for me also, this is not a trigger, but a sociological component of the perception of autism.
    You say
    I guess it's plausible, but frankly, I'd expect the data to look a lot different if any environmental trigger that worsens as time goes by were having an effect in the numbers.

    I dont think so. How can we be sure if there is not a trigger/cause but a combination of insults that make symptoms worse and worse? Being genetics the roots, what the environmental insult can do is to worsen the symptoms for me and to shift the presentation from milder to more severe forms. If we think since speech delay, through ADHD to severe autism, looking at the overall situation, how can we be so sure that the symptomatology has not worsened the last 30 years, beyond the tendency to diagnose in the case of ADHD in the last 15 years?

    Every time I look at the numbers I find more and more indications that there is no epidemic and no real regional differences. I also find more info that explains what's going on, like the fact that recognition is also increasing within the MR population.

    This could be a consequence of a situation, but not the explanation of the cause of the situation itself, that can be quite complicated.

    I hope you consider my comments not as an intention to rebuttal- that they are not-but as a productive dialogue- that it is my intention, if you are interested.


    Sincerely
    María Luján

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  5. Based on personal experience, I do think that there is a strong component of environmental insult in the presentation of ASD in MY son. The experience is not extrapolable but is valid; it is not a prove but an anecdote, BUT to prove that the majority of ASD children has not a contribution of comorbilities in the presentation of autism symptomatology it must be proven that the so called comorbilities have not relationship with the gene expression and environmental combination in ASD and this has not been proven because it has not been studied because there is not an integrative study of autism TODAY.

    I tend to believe you. Your son's autistic symptoms might either be the result or an environmental insult, or they might have made his autism more noticeable, or he's autistic and coincidentally also had an environmental insult. Your circumstances could very well be unique. (You can send me more details to joseph449008 at hotmail).

    Now, is this envionmental insult something that might cause an 'autism epidemic'?

    Autism is a lot more than a brain insult. This is clear from cognitive research, and from the experiences of autistics themselves. This is the main reason why environmental triggers don't make sense to begin with. Inferences from the data just add to that.

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  6. Joseph
    Thank you for your answer
    You say
    Now, is this environmental insult something that might cause an 'autism epidemic'
    My point is not talking in these terms because
    1-They are controversial because of the quality of the data
    2- All is reduced to the discussion of if there is or not an autism epidemy. I Think that there are more neurodevelopmental problems in general now than before, from speech delay to autism with a very long list of confirmed and potential collaborators in the TRUE situation.

    You say
    Autism is a lot more than a brain insult. This is clear from cognitive research, and from the experiences of autistics themselves.

    Absolutely agree. I do think that in autistics there is an uniqueness that is related to genetics and for me this is clear. I never, NEVER, mentioned other thing,

    This is the main reason why environmental triggers don't make sense to begin with. Inferences from the data just add to that.

    Joseph, the problem for me is the oversimplification of the situation. You still think in terms of triggers or causes. I am proposing to think as collaborators or insults.
    I think that BECAUSE of different genetics-and in this there is the root of several of the unique abilities of autistics- epigenetics and environment can play a very important role because of gene expression.

    BTW, thank you for providing me your e-mail.
    You say
    Your son's autistic symptoms might either be the result or an environmental insult, or they might have made his autism more noticeable, or he's autistic and coincidentally also had an environmental insult. Your circumstances could very well be unique.
    I do not think so. I wonder how many children diagnosed with ASD are carefully and completely tested adequately to discard concomitant medical problems.

    MAría Luján

    ReplyDelete