When most people think of autism, several symptoms and traits often come to mind—things like obsessive interest in specific topics, repetitive and restricted behaviors (lining up toys compulsively is a classic example), difficulties communicating, and inappropriate outbursts in public, just to name a few. These are also the behaviors teachers and clinicians are trained to look for when diagnosing autism. Unfortunately, however, a growing body of research suggests that the current criteria we use to diagnose Autism Spectrum Disorder (ASD) doesn’t do a great job of representing the full spectrum of people with autism.
Specifically, many girls and women with ASD are missed or diagnosed late because autism doesn’t present the same way in girls as it does in boys and, even when it does, girls sometimes hide—or “mask”—their symptoms successfully enough to fly under the radar and miss early diagnosis. Here’s what you need to know about autism masking and the reasons girls are diagnosed with ASD less often than boys.
Autism’s skewed sex ratio
Autism has long been thought to affect boys and girls disproportionately—and by significant margins. For years, the general consensus was that the autism sex ratio (the number of males with autism compared to the number of females) was 4:1. That means that, for every one girl with autism, there would be four boys with ASD. A 2017 analysis of 54 studies found that the ratio to be closer to 3:1, but some experts suspect that number may still be inflated. The data about autism’s sex ratio is skewed because research into autism is skewed. For years, autism studies have involved a disproportionately male pool of participants. As a result, much of the data we have about ASD and the way it presents really applies more to males than females or gender-diverse people (including non-binary and transgender individuals).
What is autism masking? One reason for autism’s skewed sex ratio is a phenomenon known as autism masking, which refers to behaviors a person with ASD engages in to disguise their autistic traits and better fit in with neurotypical peers. According to a 2019 review, masking was commonly reported by women with autism who had been diagnosed late and the practice “involved mimicking (an unconscious attempt) or learning (a conscious effort) socially acceptable behaviour,” usually as a result of “pressure to meet the expectations a neurotypical world imposes.”
While masking might seem, on the surface, to be a potentially positive ability, in reality, it can have harmful side effects for the people who engage in it and is considered a “relatively superficial method of coping, with resultant difficulties ranging from constant exhaustion to one woman describing a loss of her own sense of identity.” People with ASD who use masking techniques have also reported higher levels of stress and anxiety compared to people with autism who don’t engage in masking.
Why are girls diagnosed with autism less often than boys? Masking is just one factor that contributes to lower rates of ASD diagnosis among girls than boys. Others include:
Different Symptoms: It’s common for autism to present differently in girls than it does in boys—and in some very key ways. Girls with ASD frequently have less severe symptoms than boys typically do and some traits of autism present very differently among girls than they do for boys. For example, while many people associate an obsessive interest in things like trains or video games with autism, girls with ASD may develop interests of similar intensity in subjects that aren’t typically associated with autism, like fashion or their own appearance. These interests may seem more in line with those of typically developing girls and therefore go overlooked, even if the intensity of the obsession suggests ASD may be an issue.
Diagnostic Bias: Because autism studies have historically included many more boys than girls or gender-diverse participants, most of what we know about autism is about autism in boys. As a result, teachers and clinicians may not always recognize autism in girls because it presents differently for them. What’s more, because statistics have long pointed to ASD as being far more common in boys than in girls, teachers and clinicians may be on the lookout for it more among boys than girls or may look for alternative explanations when they notice symptoms in girls.
Misdiagnosis and comorbid conditions: Girls with autism are more likely to have their symptoms attributed to other conditions, such as anxiety and depression. Sometimes this can be a case of misdiagnosis, although studies have shown that autistic girls appear to be more likely than autistic boys to suffer from anxiety and depression. If a girl does struggle with anxiety or depression, symptoms that point to ASD may be misattributed to the other conditions, delaying proper diagnosis.