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Diagnostic tests for autism may miss many girls

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Deborah Rudacille
27 June 2011

Lonely child: Girls with Asperger syndrome show an interest in socializing, but have difficulty connecting with peers.

The symptoms of Asperger syndrome look slightly different in girls than in boys, according to a study published earlier this month in Research in Developmental Disabilities1. This study and a spate of other recent ones suggest that with available diagnostic tests, higher-functioning girls with autism are being diagnosed either later than boys, or are altogether missed.

In the new study, Swedish researchers showed that 18 new questions on a revised Autism Spectrum Screening Questionnaire lead to very different response profiles for school-age boys versus girls who have Asperger syndrome.

The study is a rarity, however. Gender differences in autism are poorly understood because few girls are included in research. Even when they are, few studies look specifically at gender differences.

"It's the white elephant in the room," says Marisela Huerta, clinical psychologist at the University of Michigan Autism and Communication Disorders Center. Huerta was one of the organizers of a session on sex differences at the International Meeting For Autism Research (IMFAR) in San Diego last month.

"While many people speculate about the sex differences and there are a number of anecdotal stories about girls being clinically different or a bit harder to diagnose," Huerta says, "there hasn't been a lot of empirical work done on this topic."

Autism is roughly four times more prevalent in boys than in girls. At the higher-functioning end of the spectrum, the ratio widens, with some studies reporting that Asperger syndrome is up to eight times more common in boys than in girls.

Various explanations have been proposed to explain this disparity. Genetic studies show that girls appear to be somewhat protected from the effects of rare genetic variants that seem to cause autism in boys. Girls who have the disorder tend to have large deletions and duplications of DNA and have more severe symptoms.

Girl trouble:

Some researchers have suggested that autism is a version of the 'extreme male brain' — an exaggeration of typically male traits, perhaps caused by exposure to abnormally high levels of testosterone in utero.

However, others say the skewed sex ratio, especially at the higher-functioning end of the spectrum, is at least partly because testing instruments simply miss many girls with the disorder.

"Many of these [testing instruments] are modeled on the earliest groups of children identified with autism, many of whom were boys," says Somer Bishop, assistant professor of pediatrics at Cincinnati Children's Hospital in Ohio, who co-chaired the gender differences session in San Diego.

Because the symptoms in girls are often different, "I think that very, very smart girls go undetected at higher rates than boys do," Bishop says. "[Girls] often present with more subtle difficulties."

Bishop and Huerta have been working with Catherine Lord, who developed the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview-Revised, the gold standard diagnostic tests for autism, to create short screening tools for autism.

In focus groups, Huerta says, parents of girls often note that the questions don't capture what is unusual or abnormal about their daughters' play habits.

Unlike the stereotype of the boys with autism, girls with the disorder are often interested in imaginative play — obsessively so, in some cases. "You don't expect to see a kid with autism being obsessed with a baby doll," says Bishop.

Similarly, a girl with the disorder may be socially interested and motivated, but unsuccessful in forming relationships with her peers. "We get referrals from families who are frustrated because they know in their gut that something is not going well in terms of their child's overall development, but can't quite figure out why things are so hard for their girls," Huerta says.

A few studies are beginning to tease out differences between boys and girls with higher-functioning forms of autism, but results so far are mixed.

For example, the Swedish study found that parents of a girl are more likely to report that their daughter "interacts mostly with younger children" than are parents of boys. Parents of boys are more likely to report that their son "lacks best friends" or "is viewed as a little professor" by peers.

The differences are subtle, but may reflect a greater drive for social interaction in girls with the disorder. For example, though they are often unable to interact with their peers, they can connect with younger children who will allow them to set the terms of play.

Girls in the study also "avoid demands" at a significantly higher level than boys. Other studies have reported that people with autism avoid everyday demands made by other people because they feel anxious when not in control. Girls may be more likely to avoid demands passively, by ignoring them, rather than acting out like boys.

In total, 6 of 16 items in the original test — which an earlier study found best predicted Asperger syndrome — were more typical of boys than girls in the new version.

Test pattern:

Because their symptoms are either less overt or more difficult for clinicians to recognize as indications of autism, girls may also be diagnosed at a later age.

According to unpublished results presented at IMFAR, girls with Asperger syndrome are diagnosed on average at 10 years of age, two years older than the average age of diagnosis for boys.

In that study, Dutch researchers surveyed 2,000 people with autism, including 400 women, from infancy through age 85. Parents of the younger children with the disorder answered the survey questions, but whenever possible, those with autism answered for themselves.

Many of the older women had not been diagnosed until adulthood. "They were missed in DSM-III and weren't diagnosed till the criteria [for autism diagnosis] were expanded in DSM-IV," says lead investigator Sander Begeer, assistant professor of developmental psychology at the VU University of Amsterdam.

"What we are seeing right now with Asperger's is similar to what we saw 20 years ago among women with autism," he says. "At the time it was perceived as a men's disorder."

Because there are far fewer girls diagnosed with autism, researchers tend to rely mostly on data from boys. This creates a self-reinforcing cycle in which the symptoms of boys are taken as the norm for the disorder, perhaps leading to fewer girls being diagnosed, and thus included in studies.

"It took us years to get ten girls in our low-risk sample," says Diana Robins, associate professor of psychology and neuroscience at Georgia State University, lead investigator on a study of sex differences in the early screening of autism spectrum disorders presented at IMFAR.

Robins and colleagues used the Modified Checklist for Autism in Toddlers to screen nearly 16,000 children for autism at age 18 or 24 months. Initially, males comprised about 58 percent of the 1,352 children who screened positive for autism. At each succeeding phase of the diagnostic process, the sex ratio shifted, however.

Of the 69 individuals who were ultimately diagnosed with autism, 81.2 percent were male, with 56 boys versus 13 girls. "It fits fairly well with the published sex ratio," Robins says, "so that's promising."

Robins works with younger children and says she doesn't believe her screening study missed many girls. But she acknowledges that more girls may be missed at school age or older.

More girls than boys may also be just under the threshold that separates individuals with 'clinically significant impairment' from others with more minor symptoms, she adds. "Whether there are more girls out there hovering near that threshold is an empirical question that someone needs to ask."

References:

  1. Kopp S. and C. Gillberg Res. Dev. Disabil. Epub ahead of print (2011) PubMed

Comments

Name: Jennifer Flores
18 July 2011 - 3:14AM

Dear Ms. Rudacille,
Hello. I am writing to tell you that a 36-year-old female with Aspergers, I was interested and intrigued by your article reposted in the GRASP newsletter. I wanted to personally thank you both for writing the article, and allowing it's republication with GRASP. I hope you realize you are helping many women here in the real world who are learning to deal with this difficult and often confusing issue. Thank you again, and I look forward to reading further work on the matter. Jennifer Flores

Name: Jennifer Flores
18 July 2011 - 3:19AM

Dear Ms. Rudacille,
Hello. I am writing to tell you that as a 36-year-old female with Aspergers, I was interested and intrigued by your article reposted in the GRASP newsletter. I wanted to personally thank you both for writing the article, and allowing it's republication with GRASP. I hope you realize you are helping many women here in the real world who are learning to deal with this difficult and often confusing issue. Thank you again, and I look forward to reading further work on the matter. Jennifer Flores

Name: Deborah Rudacille
18 July 2011 - 9:02AM

Thanks, Jennifer. I hope to continue following this story. There are some studies in the works that will perhaps shed more light on the issue. Thank you for reading SFARI!

Name: Christina - Happily Eccentric
12 December 2011 - 9:39PM

This article is fantastic!

I'm "unofficially officially" an Aspie. Why not officially? Because it's very difficult to get testing for adults. A lot of practitioners bill the patient (typically $2400+), then the patient has to hope her insurance will reimburse her.

Worse, I'm "social" in that I love to talk with people. Because of this, people don't believe I'm an Aspie. Sorry folks, but stick with me long enough, and you'll see my quirkiness. Yes. Like both of my brothers (who were easily dx'ed), I have Asperger's.

I started a blog about this, and about having a daughter on the spectrum (PDD-NOS): www.happilyeccentric.com

Thank you for this article.

Name: Vanessa Gibson
19 December 2011 - 6:17PM

I think that I have some Williams-Beuren syndrome gene deletions (long arm of chromosome 7) as well as Asperger's syndrome and it's deletions, SNPs and copy-number variations.

I am overfriendly (by NT standards) with strangers and match the behavioural phenotype, musicality and perfect pitch, etc.. These tendencies tend to balance and disguise some Aspie tendencies but augment the loquaciousness. You may be similar.

I get on best with strangers (WBS) but cannot make the deep connection (AS) so have few "friends" and none that I feel I could call upon, say, to be with me while I get retinal photographs for my diabetes (which causes temporary blindness and difficulty finding one's way home safely) where the hospital expects everyone to have a friend to call upon as an escort, so I cannot have this done and am thought uncoöperative as a result because diabetes folk don't know about Asperger's because they don't have to.

Having several medical conditions can prevent any of them being diagnosed or treated properly. I have Cushing's: a constantly high level of stress hormone (cortisol), that caused my diabetes and prevents diabetic control but diabetes folk don't know about Cushing's and Cushing's folk don't know about WBS, which involves a constant anxiety state and high cortisol levels masked by a warm happy disposition, while (with Asperger's) attracting abuse that adds to the stress and cortisol: vicious loops. Cushing's is a constant red-alert level of cortisol without the wake-up peak and Asperger's often comes with a gene deletion/mutation that prevents or limits melatonin production, so we have no "go-to-sleep-because-it's-nighttime" hormone peak. So I can't have confidence making appointments for anything, including getting medical help, because
I can't predict when I'll be awake/asleep.

Perhaps you should look into Williams-Beuren syndrome, aka Williams syndrome, bearing in mind that it is a pick-&-mix collection of genetic components and consequences. Our DNA doesn't know or follow the rules of those who define and describe syndromes, it just does what it does while "experts" try to make up understandings of it. Cushing's is (like) a severe form of metabolic syndrome.

Name: unduki
12 December 2011 - 10:03PM

As an older woman ironing out a confused upbringing and life, all I can say after being here all this time, wishing someone would notice, is... It's about time. Thank you for stating what's been obvious to me all my life.

Name: Angi
4 March 2012 - 6:11PM

Thank you from me too. I'm 55 and only in the last five years have worked out that I'm high functioning and autistic. I didn't speak I was over 4 years old, like counting and categorising things, highly empathic but can't recognise facial expressions, highly sensitive to noise, and have had difficulty in making close relationships.
A lengthy period of counselling for trauma/PTSD helped me learn emotional language skills. I copy social skills very well like remembering to say please and thank you; receiving compliments gracefully, not boring people with my latest obsessive interest.

Name: Keli
12 December 2011 - 10:44PM

As a 26 year old Aspie, I know I was diagnosed around 12 or 13. I've often learned with ease to adapt, but I'm still having difficulty really making friends and having the quality friendship, even though I've had 1 best friend, often among other people, I have difficulty finding common interests or activities. But my best friend and I both were rather of the misfit variety. She didn't have autism, but she craved that close friendship, and it was something I continue to treasure.

Name: Jennifer
14 December 2011 - 2:29PM

I have been saying this for years, but few pay me any attention. I am a 32 year old woman with Asperger's, but I can't pay for a formal diagnosis, so I am unofficially Asperger's. I have a son with outright Autism and a half sister who is apparently(to me and my other sister, but my dad does not see it) high functioning autism, but she does not have a formal diagnosis either, she is diagnosed with ADHD, which is not the right diagnosis for her. She is unmistakably autistic, super smart and has not one friend, she wants friends, but just can't make them, she has obsessions, and highly scattered skill sets, didn't speak until she was nearly 4 years old, has few common interests with other children her age, she is 12 now. Doesn't know how to not dominate the conversation and seems baffled that people don't like to be dominated in a conversation. I know what she is going through and I have come a long way, but still struggle with some areas of functioning, especially social appropriateness and I tend to be a "know it all", which people resent, but to be fair I don't talk about things that I don't know about, so when I do speak, I may actually know it all about that topic.

Name: Rational Gal
6 September 2012 - 12:07AM

This article doesn't actually articulate many behavioural differences...

Name: Lori Lichte-Brill
9 March 2013 - 12:01AM

I am a clinical psychologist specializing in the assessment and treatment of Autism Spectrum Disorders. This issue is one of my biggest frustrations. Even with the ADOS, considered to be the gold standard of testing, girls are often missed. The difference is that girls can answer many social and emotional questions with adequate COGNITIVE responses, often resulting in very low ADOS scores. The practical application of these, however, does not occur. When faced with a social situation, girls on the spectrum often cannot apply the information they can articulate. I have begun to rely primarily on what the new research says, as well as my clinical expertise to diagnose, and sometimes have to disregard test results. Something needs to change.

Name: Nicky10
8 November 2013 - 10:47PM

Hi Lori,

Do you take private clients? I would like to under go an assessment for myself. Are you able to help?

Victoria- Birmingham UK

Name: Heather
5 April 2013 - 12:59AM

I turn 40 this year. My almost-15yo son is dx'd with Asperger's and ADHD. The traits described here as more 'typical' of the female Aspies than the male suit him -- he has strong social desires, but very weak abilities, and has always tended to play with younger kids. However, I think it's not so much so that he could set the tone for play, but because socially/developmentally he's about 2 years behind his 'peers', so he just gets along with younger kids more as equals (though intellectually he's on par or ahead).

Anyway, when I learned about Asperger's in detail when figuring out my son, I realized... oh, hey, that's me. You probably wouldn't know it today, since I have many coping skills and am considered social, friendly, I'm very successful in my field and seen as a warm and outgoing person... Though in truth, I am an extreme introvert. More than just introversion, however -- my childhood was exceptionally difficult. Exactly as described here... unable to make friends and preferring to be with younger kids (where I was looked up to and could be in a 'mentor' role).

More to the point, it just always felt like everyone else seemed to intuitively know all the 'rules' for social interaction and I had no idea. I just kind of coasted through... even though I was a straight A+, top of the class student, I can remember times where I'd find myself walking through the halls with my class with no idea of where we were going or why... Everything was always in a bit of a fog.

I've definitely "woken up" and I'm very aware of external details and I think I'm even MORE sensitive to subtle social cues than most people are. But it took me a lot longer to get there than most.

And that 'obsessing' with imaginary play? Oh hell yes. Vivid, vivid, engrossing play, all within myself.

"Mild Aspergers" really and truly explains my childhood, in a way that was a big relief, in fact.

Name: Tami
30 August 2013 - 7:05PM

It took a while to get "officially" diagnosed,(Nov. 2012) but persistence paid off. I always knew I was "different" but didn't know how or why.Keeping a job is very hard as I don't have the "filter" for office politics. I have other symptoms of Asperger's Syndrome as well as symptoms of Autism and severe ADHD. My official diagnosis is PDD-NOS but was told since no-one knows what that is I can say that I have Aspergers Syndrome.

Name: Anonymous
8 November 2013 - 8:36PM

I am 20 years old, and I am just now starting to research the idea that I am a mild aspie.
My boyfriend (who I have been living with for almost a year now) pointed out to me the other day that I have some symptoms of an autistic (his friends younger, apdoted brother has Asbergers, he said he noticed similarities).
When I was younger, I was kind of an outcast. I was an all A student, polite, never got in trouble, was nerdy, played percussion in the school band, never enjoyed dressing up wearing makeup (still don't). Because I was so shy and odd, I got teased a lot in school. I often said odd things to my peers that didn't make a lot of sense, I can memorize song lyrics after only one listen to a song, I can memorize conversations that happened years ago. I am excellent with remembering dates and liscense plates.
I thought I was just a freak (I have 3 younger sisters, all of which are very "girly").
My parents used to get on my case about socializing and attending drinking parties, not wearing makeup, "FOR CHRIST SAKES DO SOMETHING WITH YOUR HAIR". I just always wanted to sit in my room and read, play my gameboy, and be alone.
I do not have enough money to get diagnosed officially, but I do now believe that I do have a mild case.
I am friendly and can socialize well, I just have a few close friends though.
I am so relieved that I am not alone in this. And even now as I wrote this, I have to hold back tears.
I always knew I was different, but I didn't know why.
Thank you for every woman that has posted an article, and shared their personal experiences. It has not gone unnoticed.
It has changed my life, in the best of ways.
-Bethany, Michigan

Name: nicky10
8 November 2013 - 10:38PM

Wow! I'm 36 yrs and female, its taken me nearly a year to realise and accept that I am clearly on the spectrum, high functioning autistic/ aspergers-not sure what the correct term is this year!
I researched Aspergers trying to understand a child's behaviour at the school I teach at and realised I was reading about myself- was scary, sad and exciting and then sad again!
Where do we go from here? would be interested in getting a diagnosis but don't know where to go??? would love to get learn some coping skills for when I'm feeling over loaded etc.......if there are any other women in the same situation with any advice please reply.
Some days are great and some days are just unbearable!
I now the reason behind the odd feeling from childhood....was hoping I would wake up one day and just get it, just be able to interact with ease....u know what I mean x

Name: Josephine
29 March 2014 - 2:29AM

I'm a 20 yr old Aspergers girl diagnosed in primary school. I study Medical Lab science in university and I generally get along well with everyone. The problem is that I am super shy and sensitive, not to mention have few typically feminine interests for my age group (like makeup, clubbing, dressing up. I don't know many people and have few friends but generally close ones. I don't deal with big changes well.

Name: Chelsea
13 April 2014 - 10:40AM

I'm a 25 year old female with Aspergers and I was just diagnosed this year. I think a more egregious tragedy than going un-diagnosed is being overly misdiagnosed. I went through the gamete of mental health diagnoses and consequentially, the drugs that treat them. From ADHD to ODD, to MDD, to Bipolar 2, and three different personality disorders (NPD, HPD, and BPD), OCD, and PTSD. The side effects from the medications and the underlying stigma of being a "bad" or "dysfunctional" child combined with the chaos and frustration of my sensory issues and trying to figure out why people acted the way they did/how to respond in order to gain acceptance, was nothing short of a living hell. Hopefully Psychiatry and Psychology can get it together for the next generation, because I hate to think how many girls like me there are out there being medically abused and mistreated for a Neurological difference.

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