How to Get an Autism Diagnosis

The journey to a diagnosis of Autism spectrum disorder (ASD) is a unique experience, and can often be long, confusing, and overwhelming. Because ASD presents differently for different people, and there is no official medical test for it, healthcare professionals must individually assess a person’s development and behavior over time to make a diagnosis.

Although some people receive a diagnosis as early as 18 months old (or even younger in some cases), the variability in ASD symptoms means that for some people, diagnosis is not achieved until much later in life. Age of diagnosis may also be affected by limitations such as cost and accessibility of care, as well as social stigma and stereotypes associated with ASD, and as a result, not everyone may be able to or wish to get an official diagnosis for themselves or their child.

Do you need an ASD diagnosis?

Some people identify as Autistic through self-diagnosis, and although not everyone with Autistic traits requires support, there are options available for undiagnosed or self-diagnosed Autistic people.

However, there are some benefits that come from getting an official diagnosis. It may help an Autistic person feel validated in and better understand their own experiences. A diagnosis can also be crucial for gaining access to specific interventions, supports and services.

Where do I start?

There are several phases on the journey to an ASD diagnosis. Whilst some people’s experience leading up to a diagnosis may differ, we’ve listed some of the common steps that may be taken by parents, guardians, and the healthcare team when assessing someone for an official diagnosis of ASD.

Step 1: Developmental monitoring

When we’re young, our parents and loved ones naturally observe how we are developing by watching our behaviors and how we interact with the environment and others. This is called ‘developmental monitoring’, and it’s important for making sure that children are reaching milestones and behaving in a way that is expected for their age group. It’s often during this early childhood period when parents may start noticing signs of ASD.

The CDC outlines a brief checklist for developmental milestones from 2 months to 5 years old, which you can see here. If a child is not meeting these milestones, or is showing any behaviors of concern, it is important to discuss this with a healthcare professional, such as a pediatrician or family medicine doctor.

During appointments, healthcare professionals may ask parents and guardians questions about any behaviors or delayed milestones they might have noticed during this monitoring period, to get a sense of whether the child may be showing signs of ASD. They may even interact and play with the child to assess their development.

A handy resource

Developmental monitoring can be hard to keep track of without a record. Human Health is a free mobile app that helps you track signs and symptoms daily, as well as any treatments or interventions you may be using.

You can download the app here, or by searching for ‘Human Health’ on the App Store or Google Play.

Step 2: Developmental screening

At certain times throughout childhood, children may be more formally assessed in their development, to get a deeper understanding of whether the child may be showing signs of ASD or other developmental conditions. These screenings can be performed by a variety of healthcare professionals, including doctors and nurses, and in some cases may also be completed by an educator or community worker. It’s important to note that a screening assessment is not equivalent to a diagnosis, but can provide further insight into a person’s condition and symptoms.

A screening assessment may be a questionnaire or survey that asks the parent or guardian specifics about things like the child’s movement and language skills, the way that they play and interact with others, and about their emotions. Some screening tools will assess general developmental delays, but there are also screening assessments that are specific to ASD, including the Modified Checklist for Autism in Toddlers (MCHAT), and the Screening Tool for Autism in Toddlers and Young Children (STAT).

These screenings are usually recommended at around 9, 18, 24 and 30 months of age, but if there is cause for concern, or if there is a history of ASD or developmental conditions within the family, they may be conducted at other times.

What if I’m seeking a diagnosis as an adult?

Your parents, or other people who spent lots of time with you during your childhood, may be able to provide a recount of what your development was like as a child to your healthcare professional, and if you missed any major milestones or showed signs of ASD at a young age.

It may be slightly more challenging for a healthcare professional to diagnose you with ASD without this information, but it is not impossible. Your healthcare team may also assess your behaviors, thoughts and emotions as an adult to form an official diagnosis.

Step 3: Moving towards a diagnosis

If the results of developmental monitoring and screening indicate that a child or adult may be showing signs of ASD, a healthcare professional may recommend a specialist for further assessment. Some specialists a patient may be referred to can include a developmental pediatrician, psychologist, speech-language pathologist, neurologist, geneticist or occupational therapist.

These specialists may ask parents, guardians and/or the patient to complete further questionnaires about their development and behavior. These questionnaires are designed to specifically assess whether the patient has ASD. Some examples of these questionnaires include the ADI-R (Autism Diagnosis Interview – Revised), the ADOS-G (Autism Diagnostic Observation Schedule – Generic) and the GARS-2 (Gilliam Autism Rating Scale, Second Edition).

Formally diagnosing someone with ASD means they have traits or symptoms that are known to be associated with the condition. These have been identified and studied over time through scientific and medical research.

However, as ASD is a spectrum condition and does not present the same way in everyone, it can sometimes be challenging to reach a definitive diagnosis based on a standard criteria. Although ASD does have some signs that show in a majority of people with the condition, there are a couple of reasons why many people are diagnosed later in life. Some people may not be considered to meet the criteria for an ASD diagnosis in early childhood, based on the severity of their symptoms at that time. There are a number of other conditions that tend to occur in people who have ASD, and some symptoms of ASD can also be confused for signs of other developmental or psychiatric conditions. These co-occurring and similar conditions can make it harder to make a diagnosis of ASD.

Whilst specialists trained to diagnose ASD and other developmental conditions are aware of this, it is not uncommon for people with ASD to be misdiagnosed or remain undiagnosed. There is further research being conducted to minimize the occurrence of these cases and improve the diagnostic criteria for ASD.

What next?

Once a formal diagnosis has been made, specific interventions, such as certain therapies, medications, or other supports including individual education plans or workplace accomodations may become accessible.

These supports may be useful in moderating the impact that ASD traits and symptoms can have on how a person lives and functions.

There are also a wide variety of support groups available for both parents and guardians, as well as people with ASD, that can be found online. You can find a list of them here.


Olivia Holland
Medical Writer