Investigators from Cincinnati Children’s Hospital Medical Center; Greenvale Hospital System Children’s Hospital, South Carolina; University of Kentucky College of Medicine; and Cincinnati College of Medicine retrospectively studied autistic regression, defined as deterioration of a previously acquired skill, in children with autism with and without Down syndrome.
All children were diagnosed by DSM IV-TR criteria, confirmed using the Autism Diagnostic Interview-Revised (ADI-R), and evidence of regression.
Children with Down syndrome were recruited as part of another clinical study comparing gene expression in children with Down syndrome with and without autism. Control non-Down syndrome children were identified from a research registry of children with autism spectrum disorders.
Comparisons were made on age at acquisition of language and age at loss of language and other skills as measured by the ADI-R. Language loss was defined as loss of communicative use of at least five different words that were previously used on a daily basis for at least three months. General loss of other skills was defined as loss of an ability that had been previously routine and used daily for at least three months and then lost substantially or completely for at least three months.
A total of 12 children with Down syndrome and regression were enrolled. Age range of the study participants was 4–18 years; nine of the 12 participants were male. There was no significant difference between the case and control patients with regard to the age, sex, or type of skill loss.
The mean age at acquisition of meaningful use of single words was 40.6 months in children with Down syndrome compared to 14.9 months in children without Down syndrome (P<.005).
The mean age at language loss in children with Down syndrome was 61.8 months compared to 19.7 months for those without Down syndrome (P<.01). The mean age at other skill loss was 46.2 months for children with Down syndrome and 19.5 months for controls.
The type of regression that occurred was similar in the Down syndrome and non-Down syndrome groups with the same skills being affected sequentially.
The authors conclude that when regression occurs in children with autism and Down syndrome it is, on average, much later than is typically seen in children with autism without Down syndrome.
Dr. Olasin has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.
Autism is being diagnosed with increasing frequency in the US population. Current estimates place the prevalence of autism at approximately four cases per 1,000 children in the US.1 Autism comorbidity in the Down syndrome population has been found to be as high as 7%.2
The importance of identifying and accurately diagnosing autism in children with other neurodevelopmental disorders cannot be overstated. The overlap of cognitive/intellectual...