They used to think 3 men were autistic for every 1 woman. New data shows that by age 20, it’s actually 1-to-1.
The Big Picture: Autism is likely just as common in women as in men. While boys are diagnosed earlier, girls “catch up” in their late teens and early 20s. This suggests that the “3-to-1” male-to-female ratio we’ve heard for years is likely wrong and caused by delayed diagnosis, not a lower number of autistic women.
Participant Profile:
- Who: Nearly 3 million people tracked over several decades.
- Where: Sweden (Large-scale population study).
Key Findings:
- [The Gap]: Boys are 3–4 times more likely to be diagnosed under age 10.
- [The Catch-Up]: By age 20, the number of men and women diagnosed is almost equal (1:1 ratio).
- [The Delay]: The average diagnosis age for girls in this study was 15.9, compared to 13.1 for boys.
Access Status: Free (Published in The BMJ).
Direct Link: Everyone thought autism mostly affected boys. This study says otherwise.
Adult Autism Insights 