Diagnostic Tests for Autism Often Miss Features in Girls

Males and females of any age can both be on the autism spectrum. Currently, more boys and men have been diagnosed with autism than girls and women. Is this correct, though? Perhaps just as many girls are on the autism spectrum, but are failed to be diagnosed properly.

The current standardized tests used to diagnose autism may be biased towards boys and therefore may miss girls. Similar to how the signs of a heart attack are different in women than they are in men, autism can manifest itself differently in girls than it does in boys.

As the tests are designed to pick up the more overt signs of autism, they can potentially fail to record the more subtle symptoms girls can display. This can lead to an incorrect diagnosis for a female patient.

A History of Girls on the Spectrum

Autism was first described in its modern form by Hans Asperger of the Vienna University Hospital. His original research affirmed that autism solely affected boys, and girls could not be on the spectrum. He later revised his opinion on the subject, but a similar thread has followed autism research until relatively recently in medical history.

Studies from the United States of America to Sweden found that four times as many boys as girls were diagnosed with autism. However, it has long been thought that perhaps the difference was due to the more subtle signs of autism in girls, as people often found the behavioral changes in boys more disruptive.

One theory of autism is that it accentuates normal gender differences and sends sometimes stereotypical behavior to the extreme. There has been a long-standing bias towards males in autism research. This has led to the diagnostic criteria being based on male autistic behaviors, downplaying how autism can express itself in girls.

Eliminating ADOS?

The most commonly used test to diagnose autism currently is the Autism Diagnostic Observation Schedule. ADOS was created in 1989 by Catherine Lord, Ph.D., Michael Rutter, M.D., FRS, Pamela C. DiLavore, Ph.D., and Susan Risi, Ph.D. for Western Psychological Services.

While testing a child using ADOS, the examiner spends half an hour to an hour with the child, interacting with them based on the child’s age and vocal ability. The examiner records the child’s social and communication behaviors, and uses the results to aid in diagnosing the child, either for classical autism or being on the spectrum

No one diagnostic test is perfect, though ADOS is widely used. Recent research has shown that ADOS misses a much larger percentage of girls tested than boys.

The Research

Michael Sweeney at the Somer Bishop’s Laboratory at the University of California in San Francisco reported on this study in the middle of May, 2017. They examined the ADOS scores of 396 boys and 85 girls, all of whom had already been diagnosed with autism.

On average, the children were nine years old. They controlled for differences in age and verbal abilities amongst the children. Six percent of boys did not meet the criteria to be diagnosed as on the autism spectrum according to ADOS, while a whopping fifteen percent of girls would have been missed by ADOS.

What’s the Difference?

When tested using ADOS, girls who were diagnosed to have autism had a tendency to score low in several categories. The girls tested showed fewer instances of repetitive behavior than the boys. They also seemingly had fewer severely restricted interests, where the child focused on one topic to a much greater extent than comfortable for other people.

Unfortunately, repetitive behavior and restricted interests are some of the major criteria for a diagnosis of autism using ADOS. But is autism really that different between girls and boys? Do girls really not have repetitive behaviors and restricted interests?

Another study implies that the difference is not in whether or not girls do or do not have the behaviors, but rather in how the behaviors express themselves.

The GABS Checklist for Diagnosis

David Skuse and William Mandy, at the University College London, also tackled the problem of autism diagnostic tests improperly diagnosing girls. They did so by creating a checklist they call the Gendered Autism Behaviour Scale, also known as GABS. The checklist looks at eighteen behaviors the researchers expected to be specific to how girls express autism.

They used this checklist to examine the results of the ADOS test from twenty-two boys and twenty-two girls, all of whom had been diagnosed ad being on the autism spectrum. They were all between nine and fifteen years old and were of average intelligence or above.

They found that autism expressed itself in girls more socially than in boys. Girls still expressed repetitive behaviors and restricted interests, but had a tendency to do so with relationships rather than topics such as trains or games.

Also, the restricted interest relationship had a strong tendency to be about a relationship with an animal instead of another person. Still, relationships with other people impacted girls more strongly than they impacted boys, with the girls more concerned about establishing friendships.

Girls were also more likely to be fixated on a relationship with an imaginary person. Establishing friendships, whether with their peers, imagination, or animals, were important to the girls with autism.

The difficulty of establishing these relationships, which comes from being on the spectrum, sometimes leads to increased anxiety and frustration. This anxiety and frustration is another criterion discovered as a possible criterion for a diagnosis of autism.

Adding some difficulty to the diagnosis, girls were more likely to camouflage their autism symptoms by watching their peers and imitating their behaviors. This masking of their autism appeared in boys as well, but not to the same extent.

Masking is a skill which can potentially help the children as adults when they enter the workforce and interact with narrow-minded adults, but it can also take an emotional toll. Not to mention how it can make it difficult to properly diagnose the child and get them the help they need.

It is possible that this camouflage of autistic behavior that girls express to such a skillful extent can even keep their parents from suspecting anything and so keep them from being tested for autism in the first place. Maintaining the facade can be emotionally draining enough to put these girls at risk for mental health issues as a teenager or adult.

Improvements Are Necessary

The two studies taken together show that the Autism Diagnostic Observation Schedule is in need of improvement. The focus on more outward expression of autism reveals the long-standing bias towards diagnosing male autistic behaviors.

However, now that this bias has come to light, the way has been opened for a revised diagnostic test. ADOS has already been revised once, in 2012. It is possible that the new information about its bias may lead to an additional revision. The research crew from the University College London and their GABS checklist is a good candidate for inclusion in ADOS to make a version specific to providing a good diagnosis for girls.

The Bottom Line

Girls express autism differently from boys. This poses problems with the current diagnostic criteria for autism, which uses criteria based on male expression of autism. Girls can emulate their peers and so hide their autism, and their repetitive behaviors and restricted interests tend to be directed towards relationships instead of less social outlets.

However, there is hope for more accurate diagnostic criteria in the future. With the imperfections exposed and with a greater understanding of how girls on the spectrum express themselves, the resources necessary for a more accurate diagnostic system are in place. Accurate tests will help both the children and their parents.