A review of: Begeer, S., Bouk, S.E., Boussaid, W., Terwogt, M.M., Koot, H.M. (2008). Underdiagnosis and Referral Bias of Autism in Ethnic Minorities. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-008-0611-5
The issue of under- or over-representation of a disorder within specific ethnic groups is a complicated one. There are specific disorders that are under-represented within a specific ethnic group because of some protective factor that makes such group less likely to acquire the disorder. For example, the rates of skin cancer in the African-American population are significantly lower than in the European-American population(although this has led to increase mortality rates among African Americans due to reduced screenings leading to late diagnosis). Yet, it is possible that some disorders are under-represented within an ethnic group simply because a systemic clinical bias in diagnosis and referrals. To examine this hypothesis, the authors of this study first examined 712 case records of children referred for ASD assessment in the Netherlands. They found that ethnic minority children (Turkish and Moroccan)were under-represented in this sample of referred kids as compared to Dutch children (2.1% vs. 4.4%). But does this represent a bias or is it simply that Turkish and Moroccan children are less likely to have ASD due to some protective factor? To answer this question, the authors sent 6 clinical vignettes to 82 pediatricians. The vignettes varied in their descriptions of various autism symptoms. Three ethnic background were represented, including 1) European minority (French or English) 2) Non-European minority (Moroccan and Turkish) and 3) Majority (Dutch). However, the ethnicity was independent of the clinical vignette, so that the vignette sent to one pediatrician could describe a Dutch child, while the SAME vignette sent to another pediatrician could describe a Turkish child. The authors found that vignettes describing Dutch (majority) children elicited significantly more references to autism than did vignettes describing European minority or non-European minority children. However, the mean rate of ASD based on an objective scale was equal across all three groups. This suggests that objective assessments may help minimize any potential clinical biases. ![]()
Friday, July 18, 2008
Autism and ethnic minorities: possible referral bias?
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Friday, May 9, 2008
Autism Regression: A prevalence study
A review of: Baird, G., Charman, T., Pickles, A., Chandler, S., Loucas, T., Meldrum, D., Carcani-Rathwell, I., Serkana, D., Simonoff, E. (2008). Regression, Developmental Trajectory and Associated Problems in Disorders in the Autism Spectrum: The SNAP Study. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-008-0571-9
Although most children with autism present very early signs and symptoms and a linear developmental trajectory, a small subset of children present a trajectory characterized by normal development followed by a loss of acquired skills or a failure to use the acquired skills. This pattern has been termed autistic regression. Possible explainations for this phenomenom have varied from a genetic effect on brain restructuring and pruning during the early stages of life, to enterocolitis due to vaccinations, to epilepsy. In this study, the authors explored differences in developmental outcomes for children with and without regressive autism, and the association between regression and enterocolitis and epilepsy. This study examined a population cohort born in the ![]()
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Friday, May 09, 2008 | Autism Research |
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Wednesday, May 7, 2008
Autism and Parental Psychiatric Disorders
A brief review of: Daniels, J.L., Forssen, U., Hultman, C.M., Cnattingius, S., Savitz, D.A., Feychting, M., Sparen, P. (2008). Parental Psychiatric Disorders Associated With Autism Spectrum Disorders in the Offspring. PEDIATRICS, 121(5), e1357-e1362. DOI: 10.1542/peds.2007-2296
One last comment: It's important to note that the rate of psychiatric conditions among even children with autism were very low. For example, schizophrenia was observed among 0.6% of the mothers of children with autism (compared to 0.2% of the typically developing mothers). 99.4% of the children with autism did not have mothers with schizophrenia. Therefore, the data only suggest that there may be a familial/genetic predisposition that is related to autism among very small subset of children with autism.
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Friday, April 25, 2008
Mercury Exposure and Autism: Should you check for nearby power plants?
...But this study is compelling in showing an association between mercury exposure and autism rates, and scientists can not just ignore it under the basis of its imperfect design and inability to make causal links – if that is the case, then only carefully controlled laboratory studies, with poor external validity, should be published and accepted as contributors to our greater scientific knowledge.
A review of: PALMER, R., BLANCHARD, S., WOOD, R. (2008). Proximity to point sources of environmental mercury release as a predictor of autism prevalence. Health & Place DOI: 10.1016/j.healthplace.2008.02.001
This fascinating, yet bound to be controversial, study hit the news yesterday as it was made available (pre-publication) by the Journal Health & Place. The study is simple, straightforward, elegant, with some powerful findings. In fact, the findings are somewhat daunting given the simplicity of the design. The researchers reviewed the amount of mercury release reported by industrial facilities and power plants in the State of Texas in 1997 from data provided by US Environmental Protection Agency Toxics Release Inventory. They compared these data against autism rates in 1997 and 2002 as measured by schools' autism classifications provided by the Texas Education Agency. Using a specialized geographical analysis system, the authors were able to locate each source of mercury and calculate the distance between each mercury source and each school. The results:
Industrial release of mercury and distance to industrial sources independently predicted increased rates of autism. The association with industrial release of mercury was not linear, instead the statistical model fit suggested an accelerated risk. This association remained statistically significant after controlling for specific variables such as SES, urbanicity, and race.
Power plant release of mercury and distance to power plant independently predicted increased rates of autism. In this case the association was linear (not accelerated). Again, this association remained statistically significant after controlling for other variables.
It is easy to dismiss these findings as inconsequential because they are ‘correlational’ in nature, or do not really prove anything. Researchers are too often guilty of selective acceptance of research: those studies that fit the consensus are accepted while those that don’t are dismissed for their methodological flaws – even though the studies we accept are equally flawed.
In the spirit of fairness I have to say that these findings are strong. Their methodology and analytical process are not any different from what is commonly seen in social science or epidemiology research. Is it perfect? Far from it. Is it useful or informative? Definitively! The data speak very clearly: In Texas, mercury release from industrial sources and power plants in 1997, and school proximity to these sources, are associated with rates of autism in 2002 as measured by school special education classifications.
Does this mean that mercury causes autism? Not at all. In the last sentence of the previous paragraph you can not replace the words are associated with with the word cause. There is a major difference. The data, albeit strong, have limitations. For example, the most obvious (to me) alternative explanation is that mercury release and proximity to these sources is also associated with another mystery factor that is causing this apparent association and that in fact, mercury release has nothing to do with autism rates in 2002. Let’s hypothesize that these power plants and industrial sources also release another toxin – let’s call this toxin autisimic (this is a made up toxin). These sources release mercury and autisimic at the same rate, so for each pound of mercury released there is a pound of autisimic released. It is possible then that this autisimic toxin directly increases the risk for autism, and this could explain completely the strong (but now obviously inaccurate) association between mercury release and autism.
Does this study show that vaccines cause autism? Absolutely not. I know this question may sound ludicrous to some, but I pose it rhetorically because I am certain that some will make the wide leap and link these findings to the vaccine issue.
There are other problems and limitations with this study, such as how autism rates were calculated (using all children instead of only those born inor after 1997), whether the autism rates are truly climbing and not explained by other factors, whether there are other variables that could be explaining this relation, etc, etc --- and yes, this study does not prove or directly indicate that autism is caused by mercury exposure (click here for a much more critical review of this study). But this study is compelling in showing an association between mercury exposure and autism rates, and scientists can not just ignore it under the basis of its imperfect design and inability to make causal links – if that is the case, then only carefully controlled laboratory studies, with poor external validity, should be published and accepted as contributors to our greater scientific knowledge. This is study is far, far, from perfect, and many changes should have been requested prior to publication, but I can say the same of 90% of what is published today.![]()
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Friday, April 11, 2008
Autism Rates in the USA: Where did the 1 in 150 number come from?
As I read Autism related blogs, discussion forums, and news articles, I see many people using the number 1 in 150 to refer to the current rates of autism. Yet, few know or understand where this number comes from and how it was obtained. I hope this brief review can provide some clarity on this issue:
The autism rate of 1 in 150 was published by the US Center for Disease Control in 2007 as part of a weekly disease morbidity and mortality surveillance report. The 1 in 150 rate was obtained from a population-based study of 8 year old children conducted in 2002. Specifically, teams in 15 US States reviewed health and educational records of children born in 1994. Trained clinicians classified them as having an autism spectrum disorder if:
1) had a documented previous classification of an ASD (i.e., the child had either an uncontradicted record of an autistic disorder or ASD diagnosis provided by a qualified examiner or documentation of qualification for special education services during 1994--2002 under an autism eligibility category)
or
2) did not have a documented ASD classification but had an evaluation record from an educational or clinical source indicating unusual social behaviors consistent with an ASD.
However, the clinical team conducted an additional detailed analysis of the records to ensure that the accepted DSM-IV criteria for autism and ASD was met prior to classifying each child. Thus, classification was not only based on prior records, but also included a secondary analysis by a clinical team that utilized structured procedures to maximize the validity and reliability of their diagnostic process.
The results:
Overall, the teams reported a rate of 6.6 per 1,000 children as meeting the diagnostic criteria for ASD (1 in 151). Rates by State varied significantly, but this was affected by differences in the way rates were obtained. Some States were able to determine rates based on health records AND educational records, while others could not get access to educational records. As expected, States that had access to educational records had higher prevalence rates than those that only examined health records. On average, States with access to educational and health records reported an autism prevalence rate of 7.2 per 1,000 (1 in 139), while those with only access to health record reported a rate of 5.1 per 1,000 (1 in 196). The male to female ratio significantly varied by State and ranged from 3.4 to 1 in Maryland to 6.5 to 1 in Utah.
Things to keep in mind:
- This report was based ONLY on children born in 1994. Thus it is possible that the rates could not apply to other cohorts.
- The differences in prevalence rates between States with and without access to educational records could suggest that 1) the overall rate is an underestimate because some sites only had access to health records, or 2) that the overall rate is an overestimate because some sites included cases ascertained from educational records which may be less reliable than health records.
- This rate of 1 in 150 does not refer to new cases of autism, or total cases in the population. It only speaks to cases among 8 year old children in 2002.
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Tuesday, April 8, 2008
Autism epidemic and symptom substitution
Study provides evidence for the symptom substitution theory explaining the dramatic increases in autism during the last 20 years.
A review of: Bishop , D., Whitehouse , A., Watt , H., Line , E. (2008). Autism and diagnostic substitution: evidence from a study of adults with a history of developmental language disorder.. Developmental Medicine and Child Neurology, 50, 1-5.
One theory that has been proposed as a possible explanation of the dramatic increase in autism diagnoses during the 1990’s and 2000s is the Diagnostic Substitution phenomena. The basic premise of this position is that increases in autism diagnoses are not due to a true increase in the number of ‘cases’ of autism, but instead to a change in diagnostic practices so that individuals who are now diagnosed with autism would have been diagnosed with a different condition 20 or 30 years ago.
What are the basic assumptions about this theory that can be tested? First, an increase in diagnoses of autism should be accompanied by an equally dramatic decrease in diagnoses of other related disorders that are believed to drive the substitution. Sullivan at Gray Matter – White Matter provides a great example of this phenomenon by looking at the rates of autism and mental retardation in
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Monday, April 7, 2008
Hospitalization of Children with Autism: Predictors and Frequency
A review of: Mandell, D.S. (2007). Psychiatric Hospitalization Among Children with Autism Spectrum Disorders. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-007-0481-2
In this large-scale study the authors examined the frequency and predictors of psychiatric hospitalization in children with autism spectrum disorders. The sample included 760 children and young adults with a diagnosis of autism, Asperger’s or PDD-NOS and their parents (age range of the children 5 to 21) living in Pennsylvania. 10.8% of the sample had a history of psychiatric hospitalization. A number of external factors were more common in children and young adults with ASDs. Those with a history of hospitalization were more likely to be: older, African-American, adopted, living in a single parent household, and have parents making less than 40,000 per year and without a college degree. In addition to these external factors, those with a history of hospitalization were also more likely to: have a diagnosis of Autism or Asperger’s (as opposed to PDD-NOS), display self-injurious behaviors, be aggressive towards others, display less stereotypies, and have more co-morbid diagnoses.
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Monday, April 07, 2008 | Autism Research |
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Wednesday, April 2, 2008
Injury propensity among children with Autism Spectrum Disorders.
A review of: McDermott, S., Zhou, L., Mann, J. (2008). Injury Treatment among Children with Autism or Pervasive Developmental Disorder. Journal of Autism and Developmental Disorders, 38(4), 626-633. DOI: 10.1007/s10803-007-0426-9
UPDATE: A couple of readers asked me to clarify the nature of the comparisons reported. The groups compared in the results I presented were 1,610 children with autism or PDD (some of whom also had co-morbid MR or another developmental disability) and 91,571 typically developing kids. The authors did not present sufficient information to compare the same variables between these 1,610 children and children with other developmental disabilities but not ASDs.
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Friday, March 14, 2008
Autism in South America. How does it compare?
A review of: Montiel-Nava, C., Pena, J.A. (2008). Epidemiological findings of pervasive developmental disorders in a Venezuelan study. Autism, 12(2), 191-202. DOI: 10.1177/1362361307086663
I decided to write a brief review of this article for two reasons. First, I often hear questions about how the rate of autism in the US, Canada, and the UK compare to that found in other countries. The answer to this question is relevant, although not as illuminating as most would like, to the major scientific debates regarding the perceived increase in rate in autism during the last two decades and the role of specific environmental factors in the development of autism. The second reason is more personal. Once upon a time, when Michael Jackson was on top of the charts, I called Venezuela my home.
The authors examined the rates of autism in a large metropolitan area of Venezuela, a country of 26,000,000 people with a large youth population (33% under the age of 14). In the first step of the study, the authors reviewed local medical records to identify children with a diagnosis of ASDs. The authors found 610 current cases in children between 3-9 years of age. Then, the authors independently confirmed the diagnosis in about 70% of the sample (N=430). The remaining children did not meet standard DSM-IV criteria or there was insufficient information to achieve an adequate diagnosis. This resulted in a prevalence rate of 1.7 per 1,000. Although this is much lower than reports in the US and other industrialized countries, the authors stated that unlike some previous reports, their methods provided rates for documented (identified) cases and did not include estimations of children that may be affected but have not yet been identified. In addition, the authors used only administrative sources for case identification (medical records) instead of large scale direct community assessments. Reliance on only administrative sources has been shown to provide lower prevalence rates. In summary, the rates of autism in Venezuela appear to be much lower than in other industrialized countries. However, the specific methods used in this study may have affected the results; in addition to the more common explanations, such as more limited access to specialized services, limited awareness about autism in the population, and higher stigma associated with these disorders, all of which limit service-utilization in developing countries.
A final note: I was informed by two Venezuelan MDs that thimerosal was still routinely used in vaccines in Venezuela. However, I sent a request for clarification to the pediatricians' organization in Venezuela and a governmental health official, since I was not able to confirm this information from any reliable online source. ![]()
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Wednesday, March 12, 2008
Autism services in Canada and Neuropsychological evaluations
A review of:McLennan, J.D., Huculak, S., Sheehan, D. (2008). Brief Report: Pilot Investigation of Service Receipt by Young Children with Autistic Spectrum Disorders. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-007-0535-5
This is a brief report published in the Journal of Autism and Developmental Disorders. The authors contacted over 1,100 families who had obtained services from specialized clinics for children with developmental disabilities. The centers were located in Alberta, Canada. Sixty four of these families reported having at least one child with ASD. The authors examined the different services that these families received and compared these with the recommended practice guidelines. The percentage of families receiving specific services were as follows: Speech and Language assessment (94%), Psychological Assessment (42%), Genetic Testing (31%), Speech and Language therapy (88%), occupational therapy (78%). The authors concluded that the rates of services received did not correspond with the recommended practice guidelines. The authors reported the post-diagnosis evaluation guidelines as proposed by the American Academy of Child and Adolescent Psychiatry, the National Research Council, the American Academy of Neurology, and the child Neurology Society:
1. Screening for lead, tuberous sclerosis, and Fragile X
2. Neuropsychological testing (audiological function, cognition, adaptive function, and expressive-receptive language)
3. Occupational and physical therapy assessment if needed.
My clinical practice is in pediatric neuropsychology. While working at a large hospital in Michigan conducting mostly neuropsychological evaluations for children with ASD, I assumed that most families received this service. However, once I left that setting and was exposed to clinics that do not have neuropsychological services, I realized that only a small portion of these families receive a full neuropsychological evaluation. The reasons for this vary, from limited access to trained neuropsychologists, unfamiliarity with the possible benefits of these evaluations, and sadly, limited insurance coverage in some States. In my experience, if families are informed about the nature and limitations of these evaluations, Neuropsychological evaluations are very useful in helping coordinate and determine interventions that are targeted to the pattern of strengths and weaknesses of each child, and monitor the progress of the child over time. But I also agree that some families do not find these evaluations as useful.
Here are the sources of the guidelines:
Filipek, P. A., Accardo, P. J., Ashwal, S., Baranek, G. T., Cook, E. H. Jr., Dawson, G., et al. (2000). Practice parameter: Screening and diagnosis of autism: Report of the Quality Standards Subcommittee of the American Academy of Neurology and the Child Neurology Society. Neurology, 55(4), 468–479.
National Research Council (2001). Educating children with autism. Washington, DC: National Academy Press.
Volkmar, F., Cook, E. H. Jr., Pomeroy, J., Realmuto, G., & Tanguay, P. (1999). ractice parameters for the assessment and treatment of children, adolescents, and adults with autism and other pervasive developmental disorders. Journal of the American Academy of Child and Adolescent Psychiatry, 38(12 Suppl),
32S–54S.![]()
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Friday, February 15, 2008
Autism, Services, and Co-morbidity: Insights from Kansas. PART I
Title: Characteristics of children with autism spectrum disorders who received services through community mental health centers.
Authors: Stephanie A. Bryson, Susan K. Corrigan, Thomas P. Mcdonald, and Cheryl Holmes
Source: Autism 2008 12: 65-82. (January).
Note: Co-morbidity refers to the presence of two conditions simultaneously. For example, depression has high co-morbidity with anxiety, since often people with depression also have anxiety. In research, we use the term to refer to the presence of two separate diagnoses simultaneously.
NOTE 2: This is such an interesting paper that I decided to break it into at least two review posts.
This is a basic epidemiological study from the University of Kansas that gives us some interesting data about co-morbid psychiatric disorders in children with ASDs. What services and diagnoses are obtained by children with autism, Asperger’s, PDD NOS and other childhood developmental disorders? In order to answer this question the authors examined community mental health records of 26 community centers in Kansas, through the use of a new electronic health record system that allows for the sharing of medical information between the different health centers(the great importance of such system and its possible implications for privacy violations is a very interesting topic, but a better match for a different blog). The researchers compared children who in 2004 received a diagnosis of Autism with children who received a diagnosis of a different ASD (PDD-NOS, Asperger’s). The two groups were then compared in a number of demographic factors, service use, and co-morbid diagnoses. The first amazing finding: Using very conservative estimates of autism rates (5.5 in 1000 CDC), the authors found that the Kansas community mental health system served less than 3% of children with Autism in the State and less than 15% of children experiencing other types of ASD. What happened to the 97+% of children with autism who did not receive services through the community mental health system? The authors indicated that it is possible that most children with autism in Kansas receive adequate services through the school or other State systems, so they have no need to seek services through the community mental health system. It is also possible that these children receive services privately (private ABA, therapists, evaluations, etc). Finally, a number of these children may simply not be receiving services at all. Unfortunately, the data in this paper do not help us clarify these issues. The data only tell us that less than 3% of children with autism received services through the community mental health system in the State. Is the community mental health system simply underutilized by parents of children with ASDs? Or is it simply that this system does not meet the needs of children with ASDs so that essential services are actually obtained somewhere else?
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