It’s long been thought that autism is far more prevalent in boys than girls. But findings from a new study looking at data across more than three decades suggest that may not be the case.
Researchers analyzed autism diagnosis rates for more than 2.7 million people born in Sweden between 1985 and 2022 using data from a national health register. They found that by age 20, the odds of autism were almost the same in males and females.
What differed between the genders is the age of diagnosis. Boys were more likely to be identified in childhood while the prevalence rate in girls caught up during adolescence.
Advertisement – Continue Reading Below
“Findings indicate that the male to female ratio for ASD has decreased over time and with increasing age at diagnosis,” concludes the study published this week in the journal The BMJ. “This male to female ratio may therefore be substantially lower than previously thought, to the extent that, in Sweden, it may no longer be distinguishable by adulthood.”
Across the board, the study found that autism diagnosis rates increased with each five-year interval as children grew, but for boys the peak occurred between ages 10 to 14 while the rate among girls topped out between ages 15 and 19.
Caroline Fyfe of the Karolinska Institutet in Sweden and colleagues said that the study “highlights the need to investigate why girls and women receive a diagnosis of ASD later than boys and men.”
In an accompanying editorial, Anne Cary, a patient advocate, noted that women are often misdiagnosed with psychiatric conditions.
“They are forced to self-advocate to be seen and treated appropriately: as autistic patients, just as autistic as their male counterparts,” Cary wrote.
Jorge Aguado, a clinical psychologist at the University of Barcelona in Spain who was not involved with the research, said that girls often exhibit better social skills and more language development when they are young, masking signs of autism, but that a social decline can happen during puberty. Social expectations and clinical bias also likely play a role.
“These findings invite us to review and adapt our screening and diagnostic practices, and also to adjust interventions to ensure more equitable identification and more timely and effective clinical and educational support for girls and adolescents,” Aguado said.
