Current rates of autism in girls are grossly under-estimated

Published 31 August 2020

Professor of Biomedical Science Vicki Bitsika, a clinical psychologist who has specialised in assessing and treating neuro-developmental disorders for more than 30 years, is confident that current rates of autism in girls are grossly under-estimated, and that many reach adulthood before being accurately diagnosed. She has begun extensive research to create evidence-based gendered criteria, but believes an investment of $2-3 million will be needed to complete all aspects of this work, including extensive field trials and lab-based studies.

"Autism presents differently in girls and boys, and I commonly see girls in clinical practice who have been to three to five other professionals, with the result being no diagnosis or a misdiagnosis that does not recognise their autism-based difficulties," Professor Bitsika says. "I am also seeing women who have always had difficulties in life - trouble making friends, been subject to bullying, or experienced periods of depression and anxiety - who have an autism disorder that wasn't picked up when they were young."

There has long been a belief that autism is up to four times more prevalent in boys. Their behaviour is usually more overt; they appear hyperactive, have tantrums, their communication is disordered and they have difficulties interacting with others. In boys, autism is commonly diagnosed at the ages of 3-5 years.

Girls, however, are capable of camouflaging their autism and masking the behaviours that would cause them to appear odd to others. They typically present as agreeable and desirous of acceptance, and tend to remain at the periphery of social situations, where they focus on observing and mimicking the behaviour of peers. However, that mimicking often occurs without understanding the ‘social message’ they are sending. These girls are excluded from early diagnosis and are often identified as autistic between the ages of 12-14 years, as a result of developing anxiety disorders and experiencing social isolation at school.

"This causes considerable stress and distress for the girls and their families, and the late diagnosis means that girls can become highly vulnerable to developing mental health conditions, like depression, anxiety and eating disorders, and phobias," says Professor Bitsika.

"These girls become extremely disconnected, and because they are not identified early, it becomes an equity issue. They are excluded from early intervention programs, special education funding in schools, and other post-school programs they need, so they flounder. Our failure to grapple with what autism looks like in females means we are losing a large pool of talent and potential."

For an accurate diagnosis of autism, psychologists largely consider deficits in communication and social interaction, including things like verbal and behaviour repetition. They rely heavily on symptoms outlined in the Diagnostic and Statistical Manual of Mental Disorders, however this manual is based on male experiences of autism.

Professor Bitsika wants to conduct a systematic study that establishes clear criteria for female autism and outlines the symptoms and behaviours that are distinctive to girls. Research findings will also be applied to the challenge of developing protective interventions to help minimise the onset of mental health disturbances.

"I would like to look at the phenotype in enough detail to articulate those broad categories, symptom clusters and behaviours that professionals are likely to see, and to detail the impact they have on daily function," she said. "Autism is a  spectrum condition, each means that each person will exhibit symptoms differently, however there are broad categories of impairment that we could be identifying in order to provide early support."

The work is likely to challenge long-standing wisdom on the incidence of autism in boys and girls. "In my clinical practice, it's 50/50 or, if I'm being generous, two boys with autism for every girl," Professor Bitsika said. "And the estimation that autism affects one in 100 Australians is probably an under-estimation, too."

Professor Bitsika said teasing out the differences between autism in boys and girls is likely to take a minimum of five years. It will require funding for dedicated laboratory equipment and research personnel to carry out extensive testing. However, the fallout from delayed identification or misdiagnosis, which she sees in her clinical practice  several times a month, provides ample motivation.

"Poor diagnosis costs individuals and families emotionally and financially, and has a big impact on family dynamics, as well as the learning ability and development of girls themselves," she says.

"Our findings have the potential to make life easier and more manageable for thousands of people. Autism, while classified as a disability, also entails unique abilities that are highly relevant to solving the societal problems we are grappling with. In this way, the research stands to have a great societal impact as well."

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