Autism Spectrum Disorder in an Unselected Cohort of Children with Neurofibromatosis Type 1 (NF1)

Background: Recently, studies have started to focus on the prevalence and profile of Autism Spectrum Disorders (ASD) in children with neurofibromatosis type 1 (NF1), and prevalence rates of ASD symptoms ranging between 13-30% have been reported. However, these estimates are often based on screening instruments and pre-selected samples of children with NF1 with an initial suspicion of autism spectrum problems, and are most likely not representative for the general pediatric NF1 population.

Objectives: We aimed to examine the prevalence of ASD in an unselected sample of children with NF1 without a presumption of ASD. Additionally, we assessed the predictive value of a screening- and clinical observational instrument in relation to clinical DSM-IV ASD diagnosis in a pediatric NF1 population, and we examined possible correlates.

Methods: In 128 children, aged 2-10, the Autism Diagnostic Observation Schedule (ADOS; a clinical observational instrument for ASD assessment) was administered, and 103 parents also completed the Social Responsiveness Scale (SRS; a screening instrument for autism symptoms). All children were clinically assessed by a child psychiatrist.

Results: A prevalence rate for clinical ASD of 10.9% was found. The positive predictive value in relation to the DSM-IV ASD diagnosis was highest when the screening- and observational instrument were combined. An ASD diagnosis was associated with gender and age; more boys were diagnosed with ASD and the group of children with an ASD diagnosis was older.

Conclusions: This ASD prevalence rate is clearly higher than in the general population, but lower than has been previously reported in NF1 studies using pre-selected samples of children with a presumption of ASD. Furthermore, our results highlight the importance of using both the ADOS and SRS for the identification of ASD in children with NF1.