A historical bias in the diagnostic criteria for the disorder means that millions of women reach adulthood without knowing they have autism.

Blue April, the international awareness month for Autism Spectrum Disorder (ASD), has arrived once again with campaigns, symbolic ribbons, and debates on social media. But there is one group that still remains on the margins of this visibility: women with autism.

They spent decades wondering why they felt different. They were called too shy, too sensitive, too demanding. They learned early on to observe other people and mimic their behaviors, to smile at the right moment, to feign interest when their social fatigue had already reached its limit. To the world around them, they simply seemed introverted. Autism was never even considered.

Brazil currently has 2.4 million people diagnosed with Autism Spectrum Disorder (ASD), according to the IBGE, equivalent to 1 in every 38 children between the ages of 5 and 9. But behind this number lies a distortion that experts describe as a decades-long structural problem: the diagnosis rate among men (1.5%) is significantly higher than among women (0.9%).

For researchers and clinicians, this difference does not reflect a lower actual prevalence of autism among females. It also reveals historical shortcomings in the way the disorder has been studied, described, and identified.

“Although we are aware of some genetic and structural differences between the genders, the diagnostic criteria for autism were developed largely based on studies conducted with boys. For a long time, science didn’t even ask whether this condition might manifest differently in girls,” says Dr. Letícia Amici, a psychiatrist and faculty member in the Medical Graduate Program at São Leopoldo Mandic.

The Art of Disappearing

At the heart of this underdiagnosis lies a phenomenon that researchers call “masking,” or social camouflage. From childhood onward, many girls with autism develop the ability to observe and imitate social behaviors: the way others make eye contact, how they join a conversation, how they react to a joke. It is a survival strategy, not a conscious choice, and one that occurs more frequently in women, precisely because their “social brain” tends to be slightly more developed. And it is this very characteristic that renders them invisible to parents, teachers, and, ultimately, doctors.

The cost of this invisibility, however, is high. Studies link prolonged social camouflage to severe cases of anxiety, depression, and chronic exhaustion. Women with autism have significantly higher rates of burnout and suicidal ideation than the general population. Paradoxically, it is precisely the symptoms of these comorbid conditions that usually bring them to the doctor’s office—not the autism itself.

“What we often see in clinical practice is a woman who comes to the consultation with other diagnoses, such as anxiety disorder, recurrent depression, and sometimes even borderline personality disorder. She has already undergone therapy or tried various other treatments for years, without success. And the autism was there, underlying it all—never investigated, but having a wide range of impacts, whether on social interactions, her professional career, or her overall quality of life. When we finally name it, recognize it, and begin the appropriate interventions, something changes profoundly in this woman. “There is, first of all, enormous relief in understanding that her difficulties—previously perceived as weakness or fussiness—stem from characteristics of brain function, and this also opens up new therapeutic possibilities and much more effective forms of support,” describes Dr. Letícia.

When the Diagnosis Is Made

There is a recurring pattern in psychiatric offices: a mother accompanies her child through the diagnostic process—often a boy diagnosed with autism while still in childhood—and, as she learns about the disorder, she begins to recognize herself in the descriptions. The list of characteristics she reads in her son’s report is also the story of her own life and the difficulties she faced—often without even realizing it.

“It’s a very personal moment. The mother comes to care for her child and leaves with a new understanding of herself. She begins to understand behaviors that have always puzzled her, relationships that never worked out as she’d hoped, difficulties that impacted her life path and limited her potential—as well as the constant exhaustion of trying to fit into a world that seemed to speak a different language than her own. A late diagnosis, in these cases, is immensely valuable. It doesn’t change the past, but it reorganizes the present and leads to a different future,” notes the specialist.

This pattern also highlights the urgency of training healthcare professionals capable of recognizing autism in its various forms. The Graduate Program in Psychiatry at São Leopoldo Mandic addresses ASD with an emphasis on diagnostic specifics, including the particularities of the spectrum in women and adults—an area still insufficiently covered in traditional medical training.

“Most doctors have learned to recognize autism in young boys with evident functional impairment. A 35-year-old woman who is minimally socially adapted, with a career and a family, simply does not fit this profile. These stigmas need to be reevaluated so that professionals do not perpetuate these misconceptions and can make diagnoses with greater accuracy and seriousness, without trivializing something as complex as autism,” says Dr. Letícia.

“There are some examples of women who reach their 40s or 50s without ever having received a proper diagnostic evaluation, and who do not even suspect they are on the autism spectrum. They have lived with a series of diagnoses that addressed the symptoms in isolation or superficially, but not the cause as a whole. When the correct diagnosis is finally established, it is not a sentence—it is an answer. And often, it is the first time in her life that this woman feels that things make sense,” she concludes.