Autism Gap Closes: Girls Catch Up to Boys by Age 20

For decades, doctors believed autism affected four times as many boys as girls. A massive new study from Sweden shows that assumption might be wrong.

Researchers tracked 2.7 million people born between 1985 and 2022, following them from birth up to age 37. They discovered something remarkable: while boys were more likely to be diagnosed with autism in childhood, girls caught up during their teenage years. By age 20, the ratio approached 1:1.

The study found that 78,522 people received autism diagnoses at an average age of 14.3 years. Boys were typically diagnosed around ages 10 to 14, while girls hit their peak diagnosis rate between 15 and 19. The pattern revealed something important: autism wasn't rarer in girls. It was just being spotted later.

This delay has real consequences. As girls wait years for proper diagnosis, many receive incorrect psychiatric diagnoses instead. They're often misdiagnosed with mood disorders or personality conditions, forced to navigate life without understanding why they struggle with certain things.

The researchers say this female catch-up effect raises urgent questions about why girls slip through the cracks during childhood. Current diagnostic practices may be missing autism in young girls because they often display different social behaviors than boys. Girls with autism might mask their symptoms better or show traits that don't match the male-centered diagnostic criteria doctors have relied on for years.

Why This Inspires

This research gives validation to thousands of autistic women who spent years knowing something was different but couldn't get answers. It confirms what many advocates have argued: autism in girls isn't invisible because it's rare. It's invisible because we haven't been looking in the right way.

The study's massive scale, covering an entire population over 35 years, makes these findings impossible to ignore. Medical professionals now have solid evidence that diagnostic practices need to change. When doctors know to look for autism differently in girls, more will get the support they need earlier in life.

Patient advocate Anne Cary notes these findings align with recent research showing current practices fail to recognize autism in many women until later in life, if at all. That recognition matters because early diagnosis means earlier access to understanding, community, and appropriate support.

The gap is closing, and thousands of girls will benefit from doctors finally seeing what was there all along.