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Tuesday, February 7, 2012

Ever Wondered Where All the Adult Autists Are?

The article below explores a common question in autism circles. Where are all the non diagnosed autistic adults if the current rates are reflective of better screening and diagnostic processes rather than the result of an 'epidemic'? It's tragic that so many lived a large portion of their lives being misunderstood and bullied. On the other hand the resilience of the characters in the study is nothing short of inspiring.



    May be that will work.

  2. Thanks for sharing the article. Thinking about all those families muddling through on their own with no help and no diagnosis is just... :(

  3. Just a few comments about the story you linked to, if I may.

    First, the UK study on adults is most likely wrong. Or to put it another way, the data that was included in the study does not support the idea that 1% of the adult UK population has a form of autism.

    The main problem is that the screening test used - the modified autism quotient - was simply unable to reliably find people with autism. So instead of picking out the group that was most likely to have autism and using a better test on that group, what they did was select a semi-random, biased group from the population and them used the better test on that group.

    But then they used that flawed group to make an estimate for the entire population and that estimate is almost certainly wrong. To use the words of another group that tried to validate the AQ-20 -

    "It was not possible to predict confidently which of the phase 1 respondents with AQ-20 scores of >= 5 had ASD unless they had been assessed on the ADOS-4 in phase 2."

    The other problem with the UK estimate is that the original AQ test (not the modified version) picks up a lot of people with schizophrenia in addition to people with autism. Or to put it in the words of a group of researchers - "high AQ patients with SCH cannot be distinguished from ASD by using only the scores of the total AQ and its subscales".

    Second, whenever you look at adult populations, and especially ones living in mental care facilities, you are going to have a hard time telling the difference between ID with features of autism on the low end of the spectrum and schizophrenia on the high end of the spectrum.

    On the higher side, it is difficult to tell the difference between high functioning autism and schizophrenia. Again to quote from a group of researchers (same link as last time) -

    In clinical practice, differential diagnosis of high-functioning autistic spectrum disorder (ASD) and schizophrenia (SCH) is difficult but important. It is especially difficult when adult patients with ASD have psychotic symptoms as a result of maladjustment to their circumstances. Diagnosis of ASD requires a knowledge of early developmental history, but sometimes that is difficult to clearly ascertain when the patient is an adult. If such patients were not diagnosed as having ASD during their childhood, we cannot distinguish their symptoms from the positive symptoms of SCH. Similarly, when ASD patients are in social withdrawal or in an autistic state, it is difficult to distinguish their state from the negative symptoms of SCH. Thus, a reliable measurement for differentiating the two disorders is needed.

    On the lower side, you would expect to find some people with ID who show signs of autism but don't actually have autism. You would also expect to find more people who do have autism in this group than in the general population, maybe as high as 20%.

    All of this is to say that you have to be careful when you are looking results based on people living in mental care facilities.

    None of this is to say that adults with autism don't exist - they clearly do. But the available data doesn't really support the idea that 1% of the adult population has a form of autism.

  4. Thanks for your thoughts MJ. I agree we must always be careful to critique the assertions of any study. However I do believe prior to development of better screening and assessment tools coupled with better understanding and subsequent broadening of the criteria for asd many were given false diagnosis and even those who were diagnosed correctly with autism were still often institutionalised as there was no concept of potential for learning. That would necessarily stand to reason that as the study authors found there are people still within mental health facilities with incorrect diagnosis, rather than dx of autism. Accurate rates will always be difficult to know for sure. But it still does go some way to addressing this question of where these adults are.
    I think we are on the same page for the main part. However I don't have any difficulty thinking the 1% is reasonably accurate for adults. Whilst I suspect you are more likely to consider the increase in diagnosis is possibly related to environmental changes rather than better detection?

  5. While I do think that something is triggering/causing at least part of the rise in autism cases that isn't the main reason I have hard time believing a 1% for adults.

    The main reason is that no one has been able to sample a sufficiently large population and demonstrate that the rate in adults is anywhere close to 1%.

    On the other hand, we do have a large number of results from a number of different sources that show an ever increasing number of children who have an autism diagnosis. The results show a fairly consistent pattern - the number of cases are increasing per birth year. One recent study looked at the cases in the state of California and demonstrated this pattern pretty convincingly -

    And, perhaps more importantly, when researchers go back and apply "modern" definitions of autism to an earlier population, they still can't get to 1% -

    So for me it isn't so much about what I think does or does not cause autism, it is about what research has been able to show. And, in the absence of anything directly on target, there is no reason to think that the pattern of yearly increasing numbers does not carry past the arbitrary child/adult boundary.

  6. Yes I have seen some of that research. Just last week I attended a talk by a lead autism researcher here and he suggests those increases may in part be due to technology that allows us to keep premature babies alive who might have previously died. And the choice to delay parenthood for many leading to eggs and sperm that aren't at their best. So I can see there are several potential environmental factors at play here that may account for what appear to be alarming increase in autism rates.
    But I still feel that retrospective studies, albeit problematic, trying to identify those who were misdiagnosed also offer some understanding or true rates in times past rather than simply diagnostic rates. And that this helps to put claims of an epidemic into perspective. I think these studies will always struggle to reflect true past rates due to, as you say, difficulty in obtaining a large enough sample size.