Head Motions Offer Insight into Autism for Girls

Autism was always considered to be a boy’s disorder. Girls are diagnosed with autism, too, but at a much lower rate; five times as many boys are diagnosed with autism as are girls.

That may not necessarily be because boys have autism more frequently than girls, though. It is possible that girls experience autism just as frequently, but due to diagnostic criteria, are not diagnosed as often.

Some scientists aim to close that gap by reworking the diagnosis criteria. They have looked at using functional magnetic resonance imaging scans, also known as fMRI, to detect autism in girls.

Why is there a diagnostic discrepancy?

“The criteria are male-driven, so we’re measuring females with a male ruler,” said Neuroscientist Elizabeth Torres from Rutgers University in New Brunswick

Most children receive their autism diagnosis after their behavior has been observed by outside personnel. This has turned out to be biased in favor of diagnosing boys but not girls, for several reasons.

The first is that the metrics used to diagnose autism were calibrated with boys. Societal expectations have a large amount to do with this. Many of the criteria depend on social interactions, and boys are typically socialized differently than girls.

Because girls are often expected to be quieter than boys, any social deficiencies from autism are covered up. They are also often expected to be less active, so their play with other children may also be stymied in a way that hides their exhibition of autism symptoms.

Secondly, as we have covered in the past, girls may exhibit autism differently than boys even when everything else is equal. They still have the repetitive behaviors and restricted interests, but tend to focus on relationships rather than hobby interests, and because of this can camouflage their symptoms by observing their peers.

A different diagnostic method

The most commonly used diagnostic test to uncover autism right now is known as ADOS, which stands for Autism Diagnostic Observation Schedule. It is nearly 30 years old now, having been conceived in 1989 for Western Psychological Services.

But it relies upon an examiner spending half an hour with the child. Age and vocal ability are taken into account, but it is based on social and commercial behaviors more easily observed in boys, not in girls. The “male ruler” mentioned by Torres.

The neuroscientist and her peers have come up with a diagnostic method that does not require a biased outside observer; at least, not in the same was as is traditionally used. It involves placing the child inside an fMRI machine and observing their head movements.

Head movements as a diagnostic tool

Even if you try to stay perfectly still, your body still moves in minute ways. These involuntary movements, as it turns out, can be affected by whether or not you have autism.

As Torres explains, “when you go in an fMRI machine, they tell you to hold still. But you can’t hold totally still; nobody can. The machine will pick up involuntary movements that the patient is unaware of and that an observer wouldn’t see with the naked eye.”

But would there really be a difference in head movements between boys and girls, and would an fMRI machine be accurate enough to be used for the purpose of an autism diagnosis? That is what Torres and her colleagues set out to uncover.

The researchers

Elizabeth Torres led the study and was joined by Sejal Mistry, Carla Caballero, and Caroline Whyatt. The study was titled Stochastic Signatures of Involuntary Head Micro-movements Can Be Used to Classify Females of ABIDE into Different Subtypes of Neurodevelopmental Disorders and was published in the journal Frontiers in Integrative Neuroscience.

The research

The main goal of the research was to use brain scans and the head movements thereby discovered to judge whether existing testing methods were accurate for finding autism in girls.

Brain scans from fMRI machines were used, but rather than using new scans from a small set of volunteers, the researchers decided to use already existing data. They turned to two large databases known as ABIDE I and ABIDE II.

ABIDE stands for the Autism Brain Imaging Data Exchange, the idea of which was to gather data on the brain activity of thousands of people on the autism spectrum for future research. Between the two projects, the researchers used the scans of 2,199 people, of which 309 were female; all of those scanned had either autism or Asperger’s syndrome.

The data had been anonymized in accordance with HIPAA, so they did not have access to any identifying or otherwise protected health information.

Tiny head movements were recorded as part of the ABIDE I and II data sets. This was more a by-product of the brain scanning process than an intended data point. Head movements can cause artifacts in the brain scans and have to be controlled for. Thankfully for these purposes the researchers could harvest the head motion patterns as usable data.

The researchers used this data in four different comparisons.

The first was the difference in head movements between individuals with autism and those with Asperger’s syndrome. Secondly, they looked at the difference between diagnosed individuals on medication versus those who are taking no medication.

Third was a comparison between two different forms of the ADOS diagnostic test. Fourth was a comparison between males and females, when controlling for the previous three comparisons.

Their findings

What they found was that there was a significant difference in miniscule head movements between girls with autism or Asperger’s syndrome and those who are neurotypical. This held true whether or not the diagnosed girls were on medication or were not being medicated.

They also found that the two different ADOS tests scored girls differently than boys, sometimes wildly so. The tests were very consistent with the head motion results from the brain scans for boys, but were inconsistent with the same results for girls.

Overall, the existing behavioral tests seemed to favor diagnosing boys and were not as accurate for girls, which is in line with the current 5 to 1 rate of autism diagnosis for boys versus girls. The female phenotype, how autism reveals itself in girls, is more easily masked when relative behaviors are examined.

The researchers came to the conclusion that the current generation of autism diagnostic tests were too subjective and therefore inaccurate for detecting autism in girls, and in fact had troubles with boys as well.

In their opinion, the next generation of autism diagnostic tests needs to be more data-driven and objective. They recommended the use of fMRI brain scans as a physical yet non-invasive method of looking for the symptoms autism spectrum disorders in girls. Perhaps not as the main criteria, but as a useful adjunct.

Brain scans are not necessarily the best way to uncover these useful head movements. The researchers point out a device that is worn on the head that records head movements may be a simple yet effective tool in diagnosing autism in girls.

Final thoughts

Girls are diagnosed with autism at a much lower rate than boys. The reason for this seems to be because the tests for autism are based less on objective physical examinations but rather are subjective behavioral observations. As autism and Asperger’s syndrome exhibit themselves differently in girls, this easily leads to failed diagnoses in girls.

MRI machines can detect minute head movements, even in people who are trying to be as still as possible. These head movements are different between girls on the spectrum and girls who are neurotypical. Turning this knowledge into a more accurate autism diagnosis may soon result in a small device worn on the head: simple, easy, and helpful.

References

http://www.futurity.org/detecting-autism-girls-1545632/

https://www.frontiersin.org/articles/10.3389/fnint.2017.00010/full