Autism and Childhood Disintegrative Disorder

A review of: Palomo, R., Thompson, M., Colombi, C., Cook, I., Goldring, S., Young, G.S., Ozonoff, S. (2008). A Case Study of Childhood Disintegrative Disorder Using Systematic Analysis of Family Home Movies. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-008-0579-1

I’m always hesitant to discuss or review case reports on this blog. Case reports have a very limited target audience (related researchers and clinicians) and even more limited utility. These are reports on single clinical cases, often of extremely rare conditions that are difficult to study with traditional research methods. Often, case reports include very detail information about a particular issue that is intended to stimulate questions for future research. Case reports are not intended to present generalizable data about the nature of a condition, such as the causes or efficacy of a treatment, etc. Unfortunately, case reports are often picked up by the media, which incorrectly reports the findings as scientific evidence for X or Y. Case reports, regardless of the question, population, or condition, of interest, do not provide scientific evidence for anything. They are needed, and useful, but only as they stimulate questions for future research.

In line with this position on case reports, I won’t necessary report the results of this study. Instead, I want to comment on a couple of interesting issues that the authors discussed. This case report was an examination of a child presenting with childhood disintegrative disorder (CDD). In the study, the authors examined home movies taken throughout the child’s early infancy and early childhood to validate the diagnostic description of CDD as compared to regressive autism. A major strength of this report is its use of home videos as a source of observable data about the kids’ behavior. This technique provides a great tool for both researchers and clinicians who often have to rely only on parental reports. Although home videos are not completely free of problems and biases, they do provide clinicians with added information about the child, and specially changes in the child’s behavior over time.

The authors also discussed the diagnostic overlap between childhood disintegrative disorder and childhood autism of regressive type. In this particular case report, the child showed typical development until the age of 4, which was followed by an abrupt loss of skills and functioning. After this regression, the child clinical profile was consistent with a diagnosis of autism, and he actually received a diagnosis of autism. However, upon analysis of home videos and extensive interview with the parents, the diagnosis was changed to CDD because there was no evidence of atypical development prior to the age of 4. Although in this case the differential diagnosis is clear (assuming typical development until the age of 4), when the regression occurs earlier, the differential diagnosis becomes more complex. The authors noted:

“In theDSM-IV-TR, there is a 1-year period of overlap for the timing of the regression, such that a child experiencing developmental losses between ages 2 and 3 could meet criteria for either Autistic Disorder or CDD (American Psychiatric Association 2000). Another point of potential overlap is that some reported cases of CDD present with atypical development prior to the regression (Volkmar 1992; Volkmar and Rutter 1995), just as do some children with autistic regression (Ozonoff et al. 2005)”

But why the semantic splitting? Does it really matter if the child has Autism or CDD? At the individual level, based current available treatment interventions, no. Unless, as reported in this case, access to services is more limited after a diagnosis of CDD as compared to a diagnosis of autism. Therefore, when diagnostic criteria are met for both conditions, one should consider the effect that a specific diagnosis could have on the child's ability to access needed services. But in general, the utility of this differential diagnosis may be more relevant to researchers, as it defines a possible source of heterogeneity that may inform the research on developmental trajectories, causes, and treatments for different types of autism-like childhood conditions.

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 Alabama. Another way to test this theory would be to examine retrospectively the clinical presentation of adults who have been diagnosed with a non-autism disorder, and determine if the clinical presentation of these individuals during childhood would have led to a diagnosis of Autism today. That is, would children with the same presentation receive a diagnosis of autism today?

In this study, the authors examined 38 adults (age 15 to 31) who had received a diagnosis of language disorder during childhood but not a diagnosis of Autism. The authors were mostly interested in a particular type of language disorder diagnosis called pragmatic language impairment (PLI), since this disorder has many similarities with autism. The authors conducted full ADOS and ADI evaluations of these individuals. They found that 55% of the participants with PLI met the criteria of autism as indicated by the ADOS or the ADI, and 40% met the criteria of autism as indicated by both, the ADOS and the ADI.

These findings are consistent with the diagnostic substitution theory. The implication is that a significant percentage of people who were diagnosed with PLI in the past would now receive a diagnosis of autism instead. Likely this substitution is not sufficient to explain, in its entirety, the dramatic increase in autism diagnoses; but it is reasonable to conclude that such substitution could partially explain such increase. In addition, the PLI substitution is just one of several proposed substitutions (see for example MR as described here). Finally, it could be argued that these individuals received the correct diagnosis of PLI as children and developed autism symptoms as adults. Although this is a plausible explanation, it is not consistent with what we know of the developmental progression of autism symptoms.

Autism Symptoms and Signs | A review of the DSM-IV criteria of Autism.

As several parents have contacted Translating Autism asking me to discuss the symptoms of autism spectrum disorders, I decided to write this brief post explaining the DSM-IV criteria of Autism.

Autism and related disorders are categorized within the larger concept of “Pervasive Developmental Disorders”. These disorders include: Autistic Disoder, Rett’s Disorder, Childhood Disintegrative Disorder, Asperger’s Disorder and Pervasive Developmental Disorder NOS. In this review I will focus only on the symptoms and signs of Autism, and soon I will write additional blog reviews of the diagnostic criteria for the other Pervasive Developmental Disorders.

The diagnosis of autism is made on the basis of symptoms observed or reported within 3 categories. The categories include (information in italics are examples I provide):

1. Qualitative Impairment in social interactions such as: a) impairment in the use of nonverbal behaviors (eye gaze, facial expressions, etc), b) failure to develop age appropriate peer relationships, lack of spontaneous seeking of enjoyment, interests, or achievement with others (does he/she show you something he/she made, does he/she invites you to play with him/her, etc), & c) lack of emotion reciprocity (does he/she get sad when you are sad? Does he/she show worry when you hurt yourself, etc). For diagnosis, at least two of these symptoms must be present.
2. Qualitative Impairment in communication such as: a) delay or lack of development of spoken language, b) lack of ability to initiate and maintain conversation with others, c) stereotype and repetitive language (repeating the last words you said or frequently repeating a phrase he/she heard) or idiosyncratic language (does he/she uses her own language or words for specific objects, etc, above what is expected based on the child’s age), and d) lack of varied, spontaneous make believe or interactive play (does he/she do pretend play? Does he/she engage in cooperative play with peers?). For diagnosis at least one of these symptoms must be present.
3. Restricted repetitive and stereotyped patterns of behaviors, interest, and activities such as: a) preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal in intensity or focus (is he/she obsessed with plates? Antennas? Argentina? Red dots? above and beyond what is common in today’s society – thus in most cases obsession with video games doesn’t count), b) inflexible adherence to specific, non-functional routines (do you always need to turn off the light before opening the door? etc), c) stereotyped and repetitive motor mannerisms (hand flapping, twisting, etc), and d) persistent preoccupation with parts of objects (can he/she spend hours staring at the cord of a fan, the tip of a pen, etc?) For diagnosis at least one of these symptoms must be present.

In addition to the symptoms included above, there must be a history of abnormal functioning prior to the age of 3 in at least one of these areas: Social Interaction, language use in social communication, and symbolic or imaginative play.

Also, if a diagnosis of Rett’s disorder or Childhood Disintegrative Disorder is met, such diagnoses supersede the autism diagnosis and no autism diagnosis should be provided.

Finally, note that the issue of mental retardation is not addressed anywhere in the diagnostic criteria. That is because these are two separate diagnoses that are taxonomically unrelated. The diagnosis of mental retardation is provided on the basis of IQ performance on standardize tests. If a child with autism also meets the full diagnostic criteria for metal retardation, that child may also receive a secondary diagnosis of MR, although the practice of providing such co-morbid diagnosis varies, often due to questions about the utility of such secondary diagnosis and the ability of intellectual assessment tests to accurately assess the intellectual abilities of people with Autism.

I hope you find this post useful and feel free to ask any question or request clarifications.

Nestor L. Lopez-Duran PhD
Translating Autism: An Autism Research Blog