Special needs

How Autism is Diagnosed and What to Expect in the Process

Author, Autism mom and Chair of Kerry’s Place Autism Services, Jan Stewart shares what you need to know

How Autism is Diagnosed and What to Expect in the Process

Source: Jan Stewart

When my son Andrew started kindergarten, my husband and I noticed a growing gap between him and his peers. He couldn't maintain eye contact and lacked abstract thinking skills. When his teacher told him a school rule was set in stone, he asked where the stone was kept. It was at this point we started to look into how Autism is diagnosed.

He had tantrums whenever a change in activities occurred. He repeatedly rubbed his shoulders and the top of his head in a circular motion and didn't understand social cues. And the gap widened as he grew. But because he learned to read and write on time and was a happy, chatty child, his pediatrician repeatedly discounted my concerns and told me he was just under a bit of stress—nothing to worry about.

We, parents, know our children best and are the best source of information about their development and behaviour.

How is autism diagnosed?

There is no real Autism test. It cannot be diagnosed through blood tests, laboratory tests, MRIs or X-rays. Instead, doctors use the American Psychiatric Association's Diagnostic and Statistical Manual, Fifth Edition (DSM-5) behavioural checklist to determine if a child meets the criteria for an autism diagnosis.

To do so, a child must have "persistent deficits" in social communication and interaction and restricted repetitive behaviours.

That is why doctors observe the child and ask the parents several questions. These questions typically cover the following:

  • The child's health history
  • The family's health history
  • The child's developmental milestones
  • Parental observations about the child's behaviour, both at home and in other settings
  • School reports and any other assessments completed on the child

I remember bringing videos of Andrew's behaviour that the psychiatrist found extremely helpful.

Doctors also assess the child in their:

  • Physical health
  • Hearing
  • Speech and language abilities
  • Cognitive development
  • Sensory sensitivities
  • Ability to complete age-appropriate tasks by themselves

They consider additional factors, such as pregnancy and birth complications, extreme prematurity, the parent's age, the length of time between pregnancies and medical conditions like congenital heart disease that can increase the possibility of autism. Doctors agree that none of these is the parents' fault but are essential in better understanding autism.

Because symptoms vary widely, autism is not always easy to diagnose. Other neurodevelopmental disorders, such as ADHD and anxiety, can appear similar. Children with social difficulties, for example, might not be autistic but have social anxiety.

Others might engage in repetitive behaviours due to obsessive-compulsive disorder rather than autism. And many children, like Andrew, have autism and other neurodevelopmental disorders. As Dr. Melanie Penner, Senior Clinical Scientist and developmental pediatrician at Holland Bloorview Kids Rehabilitation Hospital, states, "It's not always a case of autism or another diagnosis; many children have both."

Author Jan's two children when they were younger standing outside Source: Jan Stewart

At what age can a child be diagnosed with autism?

Some children can reliably be diagnosed as early as 18 months, while others do not demonstrate obvious signs of autism, such as social challenges, until they become toddlers or start school. However, signs and symptoms can change over time.

And some children are only diagnosed as teenagers. Dr. Evdokia Anagnostou, Vice President of Research and child neurologist at Holland Bloorview, says this is not necessarily because their doctors are not qualified but because the child can often mask their symptoms until adolescence, when the demands for social abilities increase.


For example, I met a teenager last week who told me her recent diagnosis is the missing puzzle piece in her life and has answered questions she has had about herself for years.

Remember, too, that some neurotypical children – those without any neurodevelopmental disorders -- can also display symptoms from time to time but are not autistic.

Who can diagnose autism?

The good news today is that their pediatrician or family doctor can capably diagnose many children. They don't have to wait months and sometimes years to see a specialist, a demand that has grown exponentially with greater awareness of autism.

Dr. Penner recently led a study that confirmed that many community physicians are adept at diagnosing autism. Holland Bloorview's ECHO Autism Program, which the Ontario Ministry of Health funds, has trained and supported over 200 pediatricians and family doctors.

Of course, if a parent is still worried, or if a child displays more complex behavioural signs and symptoms, asking for a referral to a specialist for a more detailed assessment is warranted.

What about group disparities in the diagnosis of autism?


Studies have reported that boys are four times more likely to be diagnosed with autism than girls. But is this true?

Beliefs about autism are changing as we learn more. Dr. Penner notes that girls are often diagnosed later, partly because they are better able to fit into social expectations than boys. They are more prone to camouflage and imitate those around them.

Biological/genetic factors that increase the likelihood of autism also affect girls and boys differently. Girls have, therefore, likely been underdiagnosed, and the gap between the sexes is narrowing.

Other studies have highlighted racial and ethnic biases. Dr. David Mandell, Director of the University of Pennsylvania's Center for Mental Health, found that many black and Hispanic children were historically diagnosed with ADHD, adjustment disorder or conduct disorder before autism.

However, with improved screening, services and awareness, marginalized groups are now "playing catch-up." Autism crosses all boundaries, and there is no evidence that different races and ethnicities have a significantly different prevalences of autism.


Reflecting on Andrew's childhood, it's hard to fathom that it took nine years to obtain the proper diagnosis. Physicians and researchers have fortunately come a long way in understanding autism and screening for it. Exciting advancements in biomarkers, genetics and environmental factors will help ease the journey for future families. And the earlier the diagnosis, the better because parents can start getting their children the right help.

If you have any concerns about your child being autistic, connect with a trusted healthcare provider!

This article was originally published on May 01, 2023

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