Ideally, all autistic kids would get diagnosed as young as possible, hopefully by age three years or younger.
“The American Academy of Pediatrics recommends that children be screened for general development using standardized, validated tools at 9, 18, or 30 months and for autism at 18 and 24 months or whenever a parent or provider has a concern.”
Concerned About Your Child’s Development?
That way they can start therapy or get accomodations, if necessary, as soon as possible.
Getting Diagnosed With Autism As an Older Teen Or Young Adult
Unfortunately, even with increased awareness and screening, some children aren’t diagnosed until they are much, much older.
“ASD can sometimes be detected at 18 months or younger. By age 2, a diagnosis by an experienced professional can be considered very reliable. However, many children do not receive a final diagnosis until much older. Some people are not diagnosed until they are adolescents or adults. This delay means that children with ASD might not get the early help they need.”
Screening and Diagnosis of Autism Spectrum Disorder
In fact, even though children can often be reliably diagnosed with autism at 18 months, when they are typically first routinely screened with the M-CHAT, many still aren’t diagnosed until they are about 4 years old.

And surprisingly, some aren’t diagnosed until they are much older, sometimes when they are adults.
“Yes, adults can be diagnosed with an ASD. Diagnosis includes looking at the person’s medical history, watching the person’s behavior, and giving the person some psychological tests. But, it can be more challenging to diagnose an adult because it is not always possible to know about the person’s development during the first few years of life, and a long history of other diagnoses may complicate an ASD diagnosis. Because the focus of ASD has been on children, we still have much to learn about the prevalence and causes of ASD across the lifespan. Behavioral interventions can be effective for adults coping with a new diagnosis of autism.”
Autism Spectrum Disorder Frequently Asked Questions
How do you screen or diagnose an older child, teen, or adult with autism?
“Parents may talk with these specialists about their child’s social difficulties including problems with subtle communication. These subtle communication issues may include problems understanding tone of voice, facial expressions, or body language. Older children and adolescents may have trouble understanding figures of speech, humor, or sarcasm. Parents may also find that their child has trouble forming friendships with peers.”
Autism Spectrum Disorder
Although the same developmental monitoring and screening tools that are available for toddlers (M-CHAT and ASQ-10) aren’t used for older children, teens, or young adults, others are available, including:
- Asperger Syndrome Diagnostic Scale (ASDS)
- Autism Behavior Checklist (ABC)
- Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), Module 4
- Autism Spectrum Screening Questionnaire (ASSQ)
- Autism Spectrum Quotient (AQ)
- Childhood Asperger Syndrome Test (CAST)
- Childhood Autism Rating Scale, Second Edition (CARS 2)
- Developmental Checklist-Early Screen (DBD-ES)
- Early Screening for Autistic Traits (ESAT)
- Social Communication Questionnaire (SCQ)
- Social Responsiveness Scale (SRS)
If you have any concerns, your pediatrician, a child psychologist, or a psychiatrist might use one of these questionnaires to screen your child.
Autistic Teenagers & Adults
So what happens when an autism diagnosis is delayed?
“Among the responses were many from people who didn’t get diagnosed until they were adults. Some had suspicions about their condition growing up. For others, the diagnosis was a revelation as much as it was a relief.”
When An Autism Diagnosis Comes In Adulthood
For one thing, you hopefully quickly understand that you are not alone, which becomes easier as you read the stories of other adult diagnosed autistic people.
“If you know you’re autistic, are beginning to wonder, share similarities with autistic people, or want to support an adult autistic friend or family member—or if you simply want to know why it’s so important that autistic adults know we’re autistic—this book is for you.”
Knowing Why: Adult-Diagnosed Autistic People on Life and Autism
And you learn that support is available if you need it, no matter what stage of life you are in, whether you are in high school, starting college, looking for a job, or getting married, etc.
More on Autistic Teenagers & Adults
- Autistic Adults
- Autism Acceptance vs Autism Awareness
- How the Anti-Vaccine Movement Hurts Autistic Families
- Thinking Person’s Guide to Autism
- Autistic Self Advocacy Network
- Welcome To The Autistic Community! Handbook
- Welcome To The Autistic Community
- CDC – Concerned About Your Child’s Development?
- CDC – Screening and Diagnosis of Autism Spectrum Disorder
- CDC – Autism Spectrum Disorder Frequently Asked Questions
- NIH – Autism Spectrum Disorder
- How early can you — and should you — diagnose autism?
- Signs of autism in adults
- Study – Evaluation of the Diagnostic Stability of the Early Autism Spectrum Disorder Phenotype in the General Population Starting at 12 Months
- How is ASD diagnosed?
- Why Many Autistic Girls Are Overlooked
- Autism diagnosis: ‘I want 40 years of my life back’
- When An Autism Diagnosis Comes In Adulthood
- Diagnosed with autism at 48, charity founder encourages celebration of neurodiversity
- 11 things I wish someone had told me when I was an (undiagnosed) autistic teen.
- Knowing Why: Adult-Diagnosed Autistic People on Life and Autism
- Knowing Why Is Everything: An Interview With Editor Elizabeth Bartmess on Adult-Diagnosed Autistic Perspectives
- I Think I Might Be Autistic: A Guide to Autism Spectrum Disorder Diagnosis and Self-Discovery for Adults
- More Than An Autism Diagnosis
- Am I Autistic?
- Diagnosis Story 22: It Seems Obvious Now
- My autism diagnosis story
- Why did I even bother to be diagnosed at all?
- Coming Out: Autism in College
- Actually Autistic Blogs List
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