Greater public awareness of autism has made early diagnosis and intervention much more likely. But new research finds this is more often the case for boys than girls.
A new study from the Kennedy Krieger Institute in Baltimore indicates that generally girls are getting diagnosed with autism at a later age than boys, perhaps because they exhibit different and less severe symptoms. This delay in diagnosis could mean a tougher road for girls with autism, said the researchers, since children with autism do best when the disorder is caught and treated early.
Autism spectrum disorders, or ASDs, are a group of developmental problems that can cause significant social, communication and behavioral challenges, according to the Centers for Disease Control and Prevention. The CDC estimates that one in 68 U.S. children has an autism spectrum disorder.
Autism is diagnosed much more often in boys than in girls. For every four boys diagnosed with autism, only one girl is found to have the disorder. In recent years, experts have started to question whether the significant sex-based differences in ASD diagnoses are a result not just of biological differences, but of a failure to recognize ASD in girls.
“There are clearly major gender differences in prevalence of autism, with more than four boys being diagnosed for every girl. However, we have little understanding of the roots of these differences,” study author Dr. Paul Lipkin, director of the Interactive Autism Network at Kennedy Krieger, told Time. “Are they biological, social, diagnostic, or tied to other factors, such as screening systems?”
To explore these sex-based differences, Dr. Lipkin’s team analyzed data from the Interactive Autism Network, an online registry of almost 50,000 individuals and family members affected by autism spectrum disorder. In the registry, age of first diagnosis was available for 9,932 children, and 5,103 had completed the Social Responsiveness Scale, which identifies the presence and severity of social impairment.
The researchers presented their findings at the Pediatric Academic Societies annual meeting in San Diego on Tuesday.
Delayed, missed diagnoses may contribute to gender disparities in ASD treatment
The team found that girls with pervasive developmental disorder, a type of ASD affecting many basic functions, were first diagnosed at a mean age of just over 4 years old, compared to 3.8 years for boys.
Girls with Asperger’s syndrome, a less severe rung on the autism spectrum which affects language and behavioral development, were also diagnosed later than boys. Girls with Asperger’s were diagnosed at a mean age of 7.6 years, compared to 7.1 years for boys.
The researchers also found that some ASD symptoms were more prevalent in girls versus boys. Girls were more likely to struggle with social cognition, or the ability to interpret social cues. On the other hand, boys were more likely to engage in repetitive behaviors such as hand flapping and were more likely to have hyper-focused and restrictive interests. Boys age 10 to 15 struggled more with the ability to recognize social cues and with language.
“These findings suggest that boys’ behavior are more apparent than the girls, with the potential for girls being more difficult to recognize,” Dr. Lipkin told Time. “Since the problems experienced by girls are in social cognition and require social opportunities, they are much more likely to be unnoticed until the elementary school years.”
Overall, the data indicated that there was an increase in the proportion of girls diagnosed with autism between 2010 and 2013 compared to 2006 through 2009, with the male to female ratio of ASD diagnoses narrowing from more than 5:1 to about 4:1. The researchers believe the increase in diagnoses for girls is a result of greater public awareness of the disorder and its signs.
However, these new findings suggest that some girls who would benefit from diagnosis and treatment still aren’t getting it because their symptoms are going unrecognized. And delayed diagnosis may not be the only problem, said Dr. Lipkin: “We must determine if the less recognizable symptoms in girls are leading not only to delayed diagnosis, but also under-identification of the condition.”