How Autism Is Diagnosed

Parents worry that any difference in their child's behavior or development could be a sign of a lifelong disability like autism. Sometimes these worries are unnecessary. Other times, careful observation can lead to early diagnosis, early treatment, and, with luck, a positive outcome. Even if autism is diagnosed and treated later in childhood—or in adulthood—treatments and support can make a big and positive difference. While it's never "too late" to be diagnosed with autism, it's never too early for a screening or evaluation. If autism is ruled out, other challenges may be caught and treated early.

Often, early signs of autism are observed by parents or grandparents. If you think that you or someone you love may have autism, you probably have noticed certain symptoms. Perhaps you've picked up on a lack of eye contact, difficulty with social relationships, speech delays, or odd physical behaviors such as rocking, finger flicking, or toe walking. It can be helpful to use an autism symptoms checklist.

If your child has just one or two symptoms but is otherwise developing normally, chances are that your child do not have autism spectrum disorder. That doesn't mean, however, that your child has no challenges. A child who has speech delays but no other symptoms, for example, may benefit from speech therapy even if the child does not have autism. Issues like these can and should be treated as soon as possible.

Older children and adults may have some or all of the symptoms as are seen in younger children. Most of the time, however, these symptoms are relatively mild—late diagnosis means that the individual has managed to compensate for autistic challenges.

Who to See for a Diagnosis

Once you've determined that something may be amiss, it's a good idea to seek a health professional to screen for autism. Your child's teacher is not a diagnostician. And while they may see worrying signs, they cannot and should not make a diagnosis. The same is true of friends and relatives who may believe they see signs of autism in your child. While it's fine to take their concerns seriously enough to schedule a professional evaluation, their "diagnosis" should never be the final word. 

The "right" professional may be a psychologist, a developmental pediatrician, or a pediatric neurologist. Your choice will, to a large degree, depend on who is available in your local area. Whatever their specialty, be sure that the expert you choose has experience with and knowledge of autism spectrum disorders.

Adults who are seeking an autism diagnosis will usually see a psychologist or psychiatrist who specializes in autism. That individual can administer appropriate tests and suggest treatments.

Because autism cannot be diagnosed with a medical test, testing involves interviews, observation, and evaluations. Screening may include:

• IQ tests to check for intellectual challenges.
• Speech evaluations to check your child's ability to understand and use spoken speech in an age-appropriate and meaningful manner.
• Occupational therapy evaluations (tests to check for age-appropriate fine motor skills, visual and spatial awareness, sensory responses, and other neurophysical concerns).
• Hearing tests (to ensure autistic symptoms are not caused by hearing loss).
• Autism-specific questionnaires, such as the ADI-R, for parents to fill out about their child's developmental milestones, behaviors, sensitivities, challenges, and strengths.
• Other tests, such as the Autism Diagnostic Observation Scale (ADOS) and The Checklist for Autism in Toddlers (CHAT), which examine observations of children's behaviors based on norms

None of these tests are perfect and some can be misleading. IQ and speech tests, for example, are written for typically developing children, but children being tested for autism almost always have behavioral and speech challenges. These challenges can get in the way of the testing process, making outcomes difficult to interpret.

Even when a professional provides an opinion, the opinion may not be definitive. It's not unusual to hear (particularly of a very young child), "It could be autism, but he's still very young. Why don't you check in again in six months and we'll see how he's doing?" While this kind of uncertainty can be extremely frustrating, it's sometimes unavoidable.

Currently, there are no diagnostic imaging tests for autism spectrum disorder. However, there is considerable research into detecting autism early by the use of brain scans. These studies include structural magnetic resonance imaging (MRI) scans and functional connectivity MRI scans. These studies have usually been done on infants who have a sibling who has autism and are therefore at greater risk.

MRI does not use radiation, so it is of lower risk than other types of imaging that do. But it is noisy and requires the child to be absolutely still, so it can be hard to get a useable scan. The percentage of false positives in the current research methods is high. In the population that is not at high risk, the procedure could result in the vast majority of babies testing positive not actually having autism.

In many cases, children have developmental challenges that resemble autism but which turn out to be simple delays or signs of other developmental issues. For example, not responding to a name could very well be a symptom of hearing impairment. Late talking could be due to aphasia or apraxia of speech.

The child's issues might be signs of another condition. They may be diagnosed with learning disabilities, attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder, narcissistic personality disorder, oppositional defiant disorder, or hyperlexia. This might be the correct diagnosis, or the child may have both autism and one of these conditions, or autism alone.

Common co-occurring mental illnesses for people with autism include depression and anxiety. People with autism have these conditions more often than people in the general population.

A Word From Verywell

For many families, an autism diagnosis can be overwhelming. It seems to change everything and it can affect your relationship with your spouse, your friends, and your child. But your child is still the person he or she always was and there's plenty of help, hope, and support available.