The diagnostic rate of autism spectrum disorders (ASD) has historically been higher among boys, with about four times as many boys diagnosed compared to girls. A new study presented Tuesday at the Pediatric Academic Societies annual meeting in San Diego, California finds that girls are diagnosed on the autism spectrum later than boys and present with different symptoms.
Researchers from the Kennedy Krieger Institute aggregated data from from the Interactive Autism Network (IAN), a web-based registry for ASD. Of the approximately 50,000 individuals registered in the database, the age of first diagnosis was available for 9,932 children between 2006 and 2013, and a completed Social Responsiveness Scale (SRS) was listed for 5,103.
Girls were found to be diagnosed with pervasive developmental disorder (PDD), a form of autism primarily affecting language and social skills, at a mean age of 4 versus 3.8 for boys. Girls were also found to be diagnosed with Asperger’s syndrome later than boys at a mean age of 7.6 compared to 7.1 for boys.
Furthermore, when analyzing results of the SRS, girls were found to have more difficulty with comprehending social cues, such as understanding the tones or facial expressions of others, understanding jokes or idioms and how to engage in a two-way conversation. Boys were found to have deficits in those domains as well as in the realm of repetitive and self-stimulatory behaviors, such as hand flapping, body rocking or scripted talk.
Many factors may lead to a delay in ASD diagnosis in girls, such as differing natural history, or under-awareness of symptom differences in young girls. This study suggests that boys have more difficulties in social awareness and communication, and girls in social cognition, which may contribute to a later diagnosis in girls. With increased public awareness, there is a trend of increased ASD recognition in girls. Future research on gender differences should compare different symptomology. Gender-specific risk factors should be taken into account for early identification of ASD.
The most alarming implication of this study is that a delayed diagnosis inevitably means delayed intervention. In light of these statistics, parents and pediatricians should be aware of any perceived or suspected developmental delays, particularly in girls, since their areas of deficit will differ from boys. The most promising outcome for all children on the autism spectrum is earlier diagnosis leading to earlier intervention.