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.