How Do Doctors Diagnose Autism?

Medically Reviewed by Smitha Bhandari, MD on January 12, 2023
3 min read

Early diagnosis can make a huge difference in the lives of children with autism spectrum disorder (ASD) and their families.

But it’s not always easy to make an ASD diagnosis. There’s no lab test for it, so doctors rely on observing the behaviors of very young children and listening to the concerns of their parents.

ASD has a very wide range of symptoms. Some people who are “on the spectrum” have severe mental disabilities. Others are highly intelligent and able to live independently.

Wherever your child falls on the spectrum, getting an autism diagnosis is a two-stage process, and it starts with your pediatrician.

Pediatricians are the first step in the autism diagnosis process. Every child gets an assessment at their 18- and 24-month checkups to make sure they’re on track, even if they don’t seem to have any symptoms.

At these visits, your child’s pediatrician will watch them and talk to them. They’ll ask you questions about family history (whether anyone in the family is on the spectrum), and about your child’s development and behavior.

Here are some milestones your doctor will be looking for:

  • Did your baby smile by 6 months?
  • Did they mimic sounds and facial expressions by 9 months?
  • Were they babbling and cooing by 12 months?

Also, they’ll ask about these things:

  • Are any of their behaviors unusual or repetitive?
  • Do they have trouble making eye contact?
  • Do they interact with people and share experiences?
  • Do they respond when someone tries to get their attention?
  • Is their tone of voice “flat”?
  • Do they understand other people’s actions?
  • Are they sensitive to light, noise, or temperature?
  • Any problems with sleep or digestion?
  • Do they tend to get annoyed or angry?

Your responses are very important in your child’s screening. If everything checks out and you have no concerns, that’s the end of it. But if your child shows developmental problems or your doctor has concerns, they will refer you to a specialist for more tests.

If your child needs more tests, your next appointment probably will be with a team of ASD specialists -- child psychologist, speech-language pathologist, and occupational therapist. You may also meet with a developmental pediatrician and a neurologist.

This evaluation is usually to check things like your child’s cognitive level, language abilities, and other life skills like eating, dressing themselves, and going to the bathroom.

For an official diagnosis, your child must meet the standards of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association.

Your child must have problems with two categories to fall on the autism spectrum.

  1. Challenges with communication and social interaction. For kids with ASD, it’s hard to “connect” with or predict the reactions of other people, read social cues, make eye contact, or have a conversation. They might not begin to speak as early as other children do. They might also have a hard time with the muscle skills needed for things like playing sports or drawing and writing.
  2. Restricted and repetitive patterns of behavior. Children with ASD might rock their bodies, repeat phrases, or become upset with changes in their routines. They’re often deeply interested in one subject. They also have sensory issues.

If your child shows potential symptoms of ASD, their doctor may monitor their development with a new device that uses data and artificial intelligence to help diagnose ASD.  The Cognoa ASD Diagnosis Aid is a machine learning–based software that follows children between the ages of 18 months and 5 years and helps evaluate and identify any developmental issues. Early diagnosis and intervention can be key to helping develop skills that will help your child.

Your child’s doctors also might recommend genetic testing to rule out any other conditions that could cause these symptoms.