How Adult Autism Is Diagnosed

Autism, clinically known as autism spectrum disorder (ASD), is a condition that affects communication and social skills; may cause increased sensitivity to sounds, smells, touch, and other things in the environment; and is associated with certain unusual behaviors.

Most people with ASD are diagnosed as children, especially those who have obvious symptoms. However, as autism has become better understood, it's not unusual for adults to wonder if certain behaviors and traits of their own (or a loved one) may be signs of ASD.

If you are among them, this article will help you understand how an adult autism diagnosis is made. It covers traits and behaviors to look for, self-screening tools, and how a mental health professional typically approaches evaluating an adult, including ruling out other possible diagnoses.

A woman talking to her doctor
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Self Observation

Adults diagnosed with autism are likely to be at the mild or high-functioning end of the spectrum.

In the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the handbook used by mental health professionals to diagnose conditions, this is known as "level 1 severity."

Many adults have mild symptoms of autism, which typically relate to social communication and sensory responses.

However, it's often not until they become more aware of what ASD is that they consider the possibility for themselves. Some may only realize it after a son or daughter is diagnosed with ASD and they notice similarities between the child's traits, behaviors, or feelings and their own.

Social Communication Symptoms

These have to do with how you interact with other people. You may come to realize you've had some of these symptoms since you were a child but you've learned to hide or manage them.

  • You aren't sure what to wear or when to speak or be quiet in social situations.
  • You use the wrong tone or word choice while talking to other people. You may speak too loudly when you should keep your voice down.
  • You have trouble interpreting other people's body language or words.
  • You struggle to keep up with conversations, especially when you aren't interested in the topic. It's especially hard for you to make small talk.
  • You're so fascinated by a particular topic you find it almost impossible to change the subject.
  • You aren't sure when it's appropriate to ask certain questions or to speak up; you may feel so uncertain you simply don't say anything at all.
  • You have a hard time coping with change. You may stick to the same schedule, eat the same foods, and take the same route to work every day, becoming upset if your routines are interrupted.

Sensory and Behavioral Symptoms

Many of these are common in all people with ASD, but may not be as obvious in those with mild autism. They may seem more like quirks than symptoms of autism.

  • You're very sensitive to light, sound, smell, touch, and taste and do not like being touched or hugged.
  • You may need physical pressure to feel calm. You may hug yourself tight if you're upset, for example.
  • You move in strange ways or make odd sounds. This is a form of self-calming called stimming. Examples include pacing, rocking, hair-twirling, and humming. If you're in public, people may stare at you, but you can't stop the behavior.
  • You have "autistic meltdowns." You get very frustrated and upset, find it impossible to control your words and actions, and may even frighten other people.

Recap

Although most people with autism are diagnosed as kids, those with mild (level 1) ASD may not be diagnosed until they're adults. The possibility may only come their attention after learning more about ASD signs (e.g., a dislike of being touch) and recognizing them in themselves or others, such as a child.

Self Tests

Self-screening tools for ASD are questionnaires you can take yourself. Most are available online at no cost. They can't confirm if you have autism. However, they can help you decide if you should see a professional to be formally evaluated.

Among the most common self-screening tools for ASD are:

  • Autism Spectrum Quotient (AQ-10): This is a 10-question screening tool adapted from a much longer questionnaire called the Autism Spectrum Quotient (AQ). The AQ-10 is very popular, but note that some research shows it may not be the most reliable way to identify someone with autism. You can take the AQ-10 test online.
  • Adult Repetitive Behaviours Questionnaire-2 (RBQ-2A): This 20-item questionnaire focuses on "restricted and repetitive behaviors." It's been found to be a highly effective screening tool for autism. You can take the RBQ-2A here.
  • Adult Social Behavior Questionnaire (ASBQ): The 44 questions in this tool focus on a wide range of aspects of autism in adults. It's especially effective for picking up on mild ASD. It can be used to evaluate someone else as well as a self-test.

Professional Evaluations

The only way to get an accurate adult autism diagnosis is to see a professional. They will observe your behavior, including how you speak and interact with them.

They will also have you complete one or more evaluations that are more detailed than those you take yourself. In most cases, you will do this by answering questions the practitioner asks you out loud.

Who to See

Some health professionals may not immediately consider autism as a possible diagnosis for an adult. Women with ASD, in particular, are often overlooked.

That's why you should seek an evaluation from someone who has experience diagnosing ASD if you decide you need to be evaluated. Ideally, this person will have a background working with adults, but this may be hard to find.

In that case, the non-profit ASD organization Autism Speaks suggests looking for a developmental pediatrician, a child psychiatrist, or a pediatric neurologist who specializes in autism and would consider evaluating an adult.

You might also look for a local autism center with a good reputation. One option: a center that belongs to the Autism Speaks Autism Treatment Network.

Diagnostic Tests

Among the tests you may be asked to take are:

  • Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) Module 4: The ADOS-2 is regarded as the gold standard for diagnosing autism in people of all ages. Module 4 is used specifically for adults and is not a questionnaire. Instead, the professional who administers the test will observe how you respond to certain prompts. They evaluate both what you say and how you behave.
  • Developmental, Dimensional, and Diagnostic Interview-Adult Version (3Di-Adult): This standard tool for diagnosing adult autism focuses on how you communicate and interact in social situations. It also looks for restricted interests, such as an obsession with a particular object, and certain behaviors.
  • Social Responsiveness Scale (SRS): This 65-question test typically isn't used to diagnose autism but instead is used to measure how impaired a person's social skills are.
  • Autism Diagnostic Interview-Revised (ADI-R): This test focuses on the three main areas affected by autism: language and communication, social interaction, and repetitive behaviors or interests. There are 93 questions in the ADI-R.

Could It Be Asperger Syndrome?

Asperger syndrome was once considered a separate autism-like disorder. However, in 2013, it was folded under the umbrella diagnosis of autism spectrum disorder (ASD) in the DSM-5. Today, what was once called Asperger's is often called high-functioning autism.

Differential Diagnosis

In adults, autism spectrum disorder can look a lot like other developmental or psychiatric disorders. These often need to be ruled out in a process called differential diagnosis.

Autism can be most easily mistaken for social communication disorder (SCD). People with SCD struggle with using words and language appropriately. They might use overly-formal words and tone during a casual conversation with a friend, for example.

What's more, research has found it's not uncommon for someone to have a psychiatric disorder along with ASD. For example, a 2019 meta-analysis found that among adults with ASD:

A provider may consider various additional evaluations depending on what other disorders they suspect.

Summary

Diagnosing autism in adults can be tricky. People who weren't diagnosed as children are likely to have mild symptoms they've unknowingly learned to cover up or manage.

That said, there are plenty of traits and behaviors a person may be aware of that could be signs of autism, such as trouble navigating social interactions and extra sensitivity to smells or touch.

People who suspect they may be on the autism spectrum can screen themselves using free questionnaires found on the Internet. But to get an actual diagnosis, it's necessary to see a mental health professional.

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2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Autism Speaks. What are the symptoms of autism?

  2. Interactive Autism Network at Kennedy Krieger Institute. Mood instability and meltdowns.

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