For decades, autism has been seen as a condition that predominantly affects boys. Recent findings from a nationwide Swedish analysis challenge that view, suggesting that the disorder may be just as common in girls once they reach adulthood.
Why the Gap Matters
The study tracked more than 2.7 million people born between 1985 and 2022, following each individual for up to 37 years. Researchers noticed a striking pattern: while boys were diagnosed earlier, girls experienced a sharp rise in diagnoses during their teenage years, bringing the gender ratio close to 1 : 1 by the early twenties.
Rising Diagnosis Rates Over Three Decades
Across the last 30 years, the overall prevalence of autism spectrum disorder has climbed steadily. Historically, boys have been identified roughly four times more often than girls, a disparity often blamed on girls’ stronger social masking abilities that make the condition harder to spot.
What the Numbers Reveal
During the follow‑up period, 78,522 participants received an autism diagnosis, representing about 2.8 % of the cohort. The average age at first diagnosis was 14.3 years.
When the data were broken down by five‑year age groups, boys peaked at ages 10‑14 with a rate of 645.5 per 100,000 person‑years. Girls, on the other hand, peaked later—ages 15‑19—with a rate of 602.6 per 100,000 person‑years. By the time individuals reached their twenties, the male‑to‑female diagnostic ratio had essentially leveled out.
Strengths and Limitations of the Research
Implications for Clinical Practice
The findings underscore a pressing need to understand why girls often receive a later diagnosis. Delayed identification can lead to misdiagnoses, especially with mood or personality disorders, and forces many young women to become self‑advocates for appropriate care.
Looking Ahead
By highlighting that autism prevalence may equalize in adulthood, this research invites clinicians, policymakers, and families to re‑examine current screening practices and ensure that all individuals—regardless of gender—receive timely, accurate diagnoses.