Autism Diagnoses Surge Tenfold As Doctors Recognizing It More In Girls

35-Year Study Shows How Condition Has Been Systematically Missed In Females

For decades, autism has been considered a condition that mostly affects boys. Now, research tracking nearly 3 million people in Sweden over 35 years reveals that supposed gender gap in early childhood might be partly an illusion created by when, not whether, girls get diagnosed.

Boys typically get their autism diagnosis around age 10 to 14. Girls? They peak five years later, between ages 15 and 19. And by the time people reach their twenties in Sweden, the numbers are approaching parity. Based on current trends, the researchers project the male-to-female ratio reached roughly equal levels by 2024. The long-standing assumption that autism is three to four times more common in males appears to reflect diagnostic timing more than actual prevalence.

Published in The BMJ, the study tracked 78,522 autism diagnoses from 1987 through 2022. What researchers found wasn’t just a shift in numbers, it was evidence that autism in females is systematically under-recognized during childhood.

The Chameleon Effect

It appears girls with autism may be better at hiding it. Researchers call this “camouflaging” or “masking,” or taking social cues from peers and mimicking their behavior to fit in. A girl who doesn’t naturally understand social rules might carefully study how other girls talk, gesture, and interact, then copy those patterns to avoid standing out.

This works reasonably well in elementary school, when social interactions are fairly straightforward. But adolescence changes everything. Friend groups become more complex. Subtle social hierarchies emerge. The unwritten rules multiply. And the exhausting effort of constantly pretending becomes harder to sustain.

That’s when the cracks start showing, but often not as “classic” autism traits. Instead, teenage girls show up in doctors’ offices with anxiety, depression, eating disorders, or burnout. And because they already have a psychiatric diagnosis, doctors may never think to look for autism underneath.

When Depression Masks Autism

This diagnostic overshadowing is one of the biggest barriers to identifying autism in females. Other research suggests nearly 70% of people with autism have at least one additional psychiatric condition. Studies in Sweden found that women are significantly more likely than men to receive other psychiatric diagnoses (anxiety, depression, OCD) before anyone considers autism.

A teenage girl struggling with an eating disorder is seen as having an eating disorder. One with severe anxiety is treated for anxiety. The underlying autism, which might actually explain why social situations feel so overwhelming or why certain routines feel essential, goes unrecognized for years.

The consequences aren’t trivial. Without understanding that autism is part of the picture, these girls miss out on appropriate support. They may internalize their struggles as personal failures rather than recognizing they’re navigating a world that doesn’t match their neurology. Women diagnosed with autism in adulthood commonly describe spending years feeling fundamentally different or “broken” before receiving an explanation that finally made sense of their experiences.

Why Screening Catches Boys But Misses Girls

Sweden has one of the most comprehensive childhood healthcare systems in the world. Every child gets screened for developmental differences at 18 months, 2.5 years, 4 years, and 5 years old. Yet girls with autism routinely slip through.

Part of the problem is that autism research has historically focused on boys and men. The diagnostic criteria and screening tools were developed based on how autism typically presents in males. Girls with autism often have different patterns of behavior. Females are less likely to line up toy cars or memorize train schedules, yet more likely to have intense interests in animals or reading that seem “normal” for girls.

Even the social difficulties look different. A boy with autism might avoid social interaction entirely. A girl with autism might desperately want friends but struggle to maintain friendships, leading to social isolation that looks more like shyness or social anxiety than a developmental difference.

The Numbers Tell The Story

While girls are catching up in diagnoses, autism rates overall have skyrocketed. For 10-to-14-year-olds, diagnosis rates increased roughly tenfold between 2000 and 2022. But the increase was even more dramatic for teenage girls, whose diagnosis rates in the 15-19 age group reached the highest of any group studied.

This surge doesn’t necessarily mean autism itself has become more common. Several factors are at play. Diagnostic criteria expanded substantially. In 1987, only severe autism was formally recognized, while today the definition encompasses a much broader spectrum. Starting in 2001, Sweden began including outpatient diagnoses in national registries, capturing cases that previously went unrecorded.

Greater awareness matters too. Parents, teachers, and individuals themselves are more likely to recognize potential signs and seek evaluation than they were a generation ago. And critically, there’s less stigma around the diagnosis, making people more willing to pursue assessment.

What This Means Going Forward

The Swedish data indicates autism doesn’t discriminate by sex nearly as much as our diagnostic systems do. The question isn’t whether girls have autism at similar rates to boys: the data increasingly suggests they do. The question is why a 10-year-old boy with autism gets identified and supported while a 10-year-old girl with the same condition gets missed, only to be diagnosed five years later after years of struggle.

That’s the real cost of late diagnosis. Not just delayed support, but years of self-blame and confusion that could have been avoided. As autism diagnoses continue to rise, understanding why girls are systematically identified later than boys isn’t just an academic question. It’s about ensuring that girls don’t spend their formative years without answers, struggling alone with challenges that have a name, even if nobody has thought to look for it yet.

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Disclaimer: The experiences described may not reflect every individual’s journey with autism. If you have concerns about autism or developmental differences in yourself or your child, consult with a qualified healthcare provider or developmental specialist.

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