Why Girls With Autism Are Diagnosed Later Than Boys

A new study looking at gender differences among children with autism spectrum disorders (ASD) show that girls have different, less obvious symptoms compared to boys, which could be why they are generally diagnosed later.

“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,” says study author Dr. Paul Lipkin, director of the Interactive Autism Network at the Kennedy Krieger Institute in Baltimore. “Are they biological, social, diagnostic, or tied to other factors, such as screening systems?”

Lipkin and his colleagues looked at data on people with ASD and their family members using the Institute’s online registry of 50,000 people. Almost 10,000 of them had reported how old they were when they were first diagnosed, and about 5,000 had undergone a test to identify their severity of social impairment. The study author’s results were presented at the Pediatric Academic Societies annual meeting in San Diego.

The researchers found that in general, girls were diagnosed with ASD later than boys. On average, girls were diagnosed with pervasive developmental disorder—an autism spectrum disorder that impacts basic skill development—at age four, and boys were diagnosed with the same disorder at about 3.8 years. Girls were diagnosed with Asperger’s syndrome around age 7.6 years, while boys were diagnosed around 7.1 years. Interestingly, the researchers noticed that the symptoms reported among the children differed by gender, too. Girls tended to have more issues with the ability to read social cues, and boys had more mannerism-related issues like repetitive behaviors including hand flapping. When boys were older, around age 10-15, they had more social issues like trouble communicating in social settings than girls did.

“These findings suggest that boys’ behavior are more apparent than the girls, with the potential for girls being more difficult to recognize,” says Lipkin. “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.”

The researchers say their findings suggest that the symptom differences may not only lead to delayed diagnosis in girls, but potentially missed diagnoses altogether. Understanding the various ways children with ASD present may lead to a better understanding of the disorders.