FOLLOW-UP STUDY

Developmental Trajectories Among Children with
Pervasive Developmental Disorders

Summary of Findings from a Follow-up Study of Children
with Autism and Asperger Disorders

Principle Investigator: Peter Szatmari, M.D.
Co-investigators: Susan Bryson, PhD; Michael Boyle, PhD

The purpose of this study is to see whether children with Asperger syndrome (AS) have a different outcome than children with high-functioning (HF) autism, and to identify factors associated with outcome and prognosis that will lead to measures that enhance the life quality of these children and their families. It is the most comprehensive and longest-lasting follow-up study of children with HF autism in the world and the only study that has focused on Asperger syndrome.

A total of 68 children, all with IQs above 70, are participating in the study. All assessments have been made using the Autism Diagnostic Interview (ADI). The initial assessment was made when the children were four years of age, after a confirmed diagnosis of PDD. Follow-up testing was done when the children were between 6 and 8 years of age, repeated when the children were 10-12 years of age, and again when they were 13-17 years of age.

Findings on PDD Children as a Group:

The outcome of high-functioning PDD children was found to be better than originally thought, at least in the transition from preschool to school age years. Significant gains were made in language, communication and social skills over time, with the result that:

• 10% of children with HF autism or AS at 4-6 years of age no longer meet the criteria for autism two years later, and

• 25% of non-verbal autistic children became verbal by 6-8 years of age;

Contrasting with this steady improvement, however, was remarkable instability in autistic symptoms. Some autistic behaviors, such as lack of affection and lack of comfort seeking, were infrequent at 6-8 years. On the other hand, new autistic symptoms appeared or became more apparent with emerging communication and social skills. These included not only language related behaviors such as echolalia, but also more rituals, more restricted interests, and resistance to change.

Comparison of AS and Autistic Children:

In general, the AS children were found to have better language and social skills and fewer autistic symptoms than the children with HF autism in late childhood and into early adolescence. However, some continue to have real difficulties, especially in high school, coping with the social demands of being a teenager and with academic expectations. Some children with autism also do well, especially those who have developed good language skills before 8 years of age. In fact, once they develop fluent language, the children with autism look more and more like the children with Asperger syndrome.

Emergence of Psychiatric Diagnosis:

As part of the Phase 4 assessment (children aged 13-17 years), and in response to parents’ concerns about emotional and behavioral problems that were emerging in their children, all the children received a careful psychiatric evaluation. From this evaluation, it was found that upwards of 40% of the children with autism and AS children had experienced at least one episode of a serious anxiety disorder or a depression at some point during adolescence. This is a much higher rate than the general population and means there is something about PDD that places the children at risk of these disorders. A fifth phase of the study is now underway to see how long the anxiety disorder and depression persists. The results to date suggest that the depression experienced by adolescence with PDD is transient. Six children seen during this phase of the study had a depressive disorder at Phase 4; however, four of these children did not present with depression at Phase 5. On the other hand, it appears that global anxiety disorders (GAD) do tend to persist in these children. To date, nine of the children had a diagnosis of GAD at Phase 4; of these, seven are still presenting with GAD. Although these findings are preliminary, the trend suggests that depression is episodic and anxiety is more longstanding in adolescence with PDD. It also appears that those who present with psychiatric disorders are the children who have better communication skills, specifically language comprehension. It seems that the better the language, the more likely the teenager will experience an anxiety disorder or depression. It could be because children with better language have a better understanding of social-emotional situations and this greater insight leads to depression. Further testing is being done to see if this is true. Information about family history is also being gathered to determine if a family history of anxiety or depression in parents or typical siblings might be associated with this increased risk. If we can understand why this group of children are at such high risk of anxiety and depression, we can begin to think of treatments that can address these problems.