How to Diagnose ASD in Adults

Have you ever thought that you may have ASD? Do you suspect a relative or close person may be suffering from this disorder? In fact, data suggests that people with high-functioning ASD often go undiagnosed. Keep reading If you want to know how this condition is evaluated in adults.

Written and verified by the psychologist José Padilla.

Last update: 11 October, 2023

Autism Spectrum Disorder (ASD) is a neurodevelopmental problem whose difficulties are reflected in social interaction, communication, the presence of stereotyped behaviors (rigid and repetitive), resistance to change, and restricted interests. The way in which this disorder is expressed varies from one person to another and is dependent on the stage of the illness.

Most people with ASD are diagnosed in childhood. They can also be diagnosed in adulthood, although it’s rather more difficult to identify at this stage. Without a doubt, ASD is becoming more frequent, and its prevalence is estimated to be 1 in 68. This increase in cases could be attributed to increased awareness, overdiagnosis, or overly inclusive diagnostic criteria.

Symptoms of autism spectrum disorder

People with ASD have difficulty communicating and interacting socially. As a rule, they also have limited interests and repetitive behaviors. In addition, they experience difficulties with cognitive and behavioral flexibility, altered sensory sensitivity, sensory processing difficulties, and emotional regulation difficulties.

Next, we’ll review the criteria that the APA (American Psychological Association) has established to diagnose ASD.

A. Persistent deficits in social communication and social interaction in various contexts, as manifested by the following, either currently or historically. These examples are illustrative, but not exhaustive.

1. Deficits in socio-emotional reciprocity. Abnormal social approaches and failure of normal two-way conversations. A decline in shared interests and emotions. Failure to initiate or respond to social interactions.
2. Impairments in nonverbal communicative behaviors. Poorly integrated verbal and nonverbal communication. Abnormalities in eye contact and body language. Impairments in the understanding and use of gestures. In more severe cases, a total lack of facial expression and non-verbal communication.
3. Problems in developing, maintaining, and understanding relationships. Difficulties in adjusting behavior in various social contexts. Difficulties in sharing imaginative games or making friends. There may be a complete lack of interest in other people.

B. Restrictive and repetitive patterns of behavior, interests, or activities, manifested in two or more of the following:

1. Stereotyped or repetitive movements, use of objects, or speech. For instance, simple motor stereotypies, alignment of toys or relocation of objects, echolalia, and idiosyncratic phrases.
2. Insistence on monotony, excessive inflexibility of routines, or ritualized patterns of verbal or nonverbal behavior. For example, great distress over small changes, difficulties with transitions, rigid thought patterns, greeting rituals, needing to take the same path, or eating the same foods every day.
3. Extremely restricted and fixed interests. These are abnormal in intensity or focus. For instance, strong attachment to or preoccupation with unusual objects or excessively circumscribed or pervasive interests.
4. Hyper- or hyporeactivity to sensory stimuli. Also, unusual interest in sensory aspects of the environment. For example, apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive sniffing or feeling of objects, and visual fascination with lights or movement.

C. Symptoms must be present early in the developmental period. However, they may not fully manifest until social demands exceed limited capacities. Alternatively, they may be masked by learned strategies later in life.

D. The symptoms cause clinically significant impairment in social, occupational, or other important areas of usual functioning.

E. These disturbances can’t be better explained by intellectual disability (intellectual developmental disorder) or global developmental delay.

Nevertheless, intellectual disability and autism spectrum disorder often coincide. To make comorbid diagnoses of autism spectrum disorder and intellectual disability, social communication must be below that expected for the general level of development.

Assessment of ASD in adults

There are questionnaires that people can take to decide if they should see a professional for an evaluation. However, they should be approached with caution because they’re not suitable for generating a diagnosis. Therefore, they shouldn’t be relied upon to confirm ASD.

Among the most common self-assessment tools for ASD are the following:

• Autism Spectrum Quotient (AQ-10). This is a ten-question assessment tool adapted from a much longer questionnaire called the Autism Spectrum Quotient (AQ).
• Adult Repetitive Behaviors Questionnaire-2 (RBQ-2A). This 20-item questionnaire focuses on ‘restricted and repetitive behaviors’.
• Adult Social Behavior Questionnaire (ASBQ): The 44 questions in this tool focus on a wide range of aspects of autism in adults. It can be used to assess another individual as well as a self-assessment tool.

Professional evaluations

Consulting a health professional is the only way to receive a diagnosis of ASD. They’ll be in charge of observing the patient’s behavior, including the way they speak and interact.

Furthermore, they’ll ask the individual to complete one or more assessments that are more detailed than those we mentioned above. Some of them are as follows:

• Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) Module 4. This is considered to be the gold standard for diagnosing autism in people of all ages. Module 4 is used specifically for adults and isn’t a questionnaire. Instead, the professional administering the test will observe how they respond to certain prompts. They evaluate both what the individual says and their behavior.
• Developmental, Dimensional, and Diagnostic Interview-Adult Version (3Di-Adult). It focuses on how the patient communicates and interacts in social situations. It also looks for restricted interests, such as obsession with a particular object and certain behaviors.
• Social Responsiveness Scale (SRS). This test isn’t used to diagnose autism, but to measure the impairment of social skills.
• 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.

The National Institute for Health and Care Excellence (2021) recommends screening for possible autism when a person experiences one or more of the following problems:

• Persistent difficulties in social interaction.
• Persistent difficulties in social communication.
• Stereotyped behaviors (rigid and repetitive), resistance to change, or restricted interests.
• Problems getting or keeping a job or education.
• Difficulty initiating or maintaining social relationships.
• Previous or current contact with mental health or learning disability services.
• History of a neurodevelopmental condition (including learning disabilities and attention deficit hyperactivity disorder) or a mental disorder.

The evaluation of ASD in adults should always be carried out under the direction of a professional, since the picture may have similarities with other disorders that can confuse the non-expert.

These disorders are ruled out through differential diagnosis. Autism can be easily confused with social communication disorder. People with this problem have difficulty using words and language appropriately.

Treatment of ASD in adults

Some interventions that can be used to treat ASD in adults include the following:

• Cognitive-behavioral therapy. During sessions, people learn about the connections between feelings, thoughts, and behaviors. This can help them identify the thoughts and feelings that trigger their negative behaviors.
• Social skills training. With these skills, the adult with autism can learn to interact with others. In addition, they’ll learn how to conduct a conversation, understand humor, and read emotional cues.
• Speech therapy. They learn verbal skills that can help them communicate better.
• Occupational therapy. They learn the fundamental skills needed to function in their daily lives.

Finally, ASD in adults is a disorder that also affects their family environment. Therefore, the evaluation of the disorder should include a conversation with the relatives or loved ones of the patient. In fact, assessing their support group is an excellent way to better understand how they relate to others and how their life is in society.