Understanding Specialized Tests for Autism

Autism spectrum disorder (ASD) is a neurodevelopmental condition with many presentations, but its main symptoms are social deficits, repetitive routines, and restricted behaviors. When ASD is diagnosed early, there are more opportunities for effective, personalized interventions. These interventions can help children with ASD develop skills to enhance their quality of life and promote independence in adulthood. In addition, parents of children who receive early diagnoses and interventions often experience less stress and anxiety.

Diagnosing ASD can be challenging because there aren’t any medical tests that can confirm it. However, multiple forms of autism testing exist and can be used to cumulatively come to an accurate diagnosis. Emerging technologies also show promise in aiding the diagnostic process.

What Is Autism Spectrum Disorder?

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects a person’s social skills and overall behavior. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) lists the following diagnostic criteria for ASD^[1]:

• Persistent deficits in social interaction and communication that occur in multiple settings
• Repetitive and restricted patterns of activity, interest, and behavior (repetitive movements, strict adherence to routines, fixated interests, and over or underreactions to sensory stimuli)
• Symptoms that are present from early childhood and contribute to functional impairment

As its name implies, ASD is a spectrum with many unique presentations. Not all people with autism spectrum disorder display the same symptoms or experience the same challenges. The DSM-5 includes various specifiers to further clarify a diagnosis^[1]:

• With accompanying language impairment
• Without accompanying language impairment
• Associated with a known medical or genetic condition or environmental factor

There are also three severity levels of ASD described in the DSM-5, each requiring different levels of support^[1]:

• Level 1 (requiring support)
• Level 2 (requiring substantial support)
• Level 3 (requiring very substantial support)

Prevalence and Importance of Early Interventions

Around 1% of the population worldwide is believed to have autism spectrum disorder. As this disorder can greatly impact a person’s overall function and mental health, early detection, intervention, and access to resources are crucial. Children with ASD may struggle at school due to challenges with social skills. Their sensory sensitivities and aversion to change can also significantly impact daily life.

When ASD is diagnosed and treated before or at preschool age, interventions are more likely to result in major long-term positive effects. According to the National Institute of Child Health and Human Development, “Early interventions give children the best start possible and the best chance of developing to their full potential. The sooner a child gets help, the greater the chance for learning and progress.”

Early intervention programs are often personalized and involve a combination of family training, occupational therapy, physical therapy, speech training, nutrition services, and hearing impairment services. Other services, such as behavior therapy, may be included depending on the person’s specific needs^[2].

The Autism Diagnostic Interview-Revised (ADI-R)

The Autism Diagnostic Interview-Revised or ADI-R, in combination with the ADOS (discussed below), is viewed as the gold standard for ASD diagnosis. Anyone who is at least two years old can undergo the ADI-R autism assessment, which consists of a 90 to 150-minute interview between a trained examiner and a caregiver who is familiar with the individual’s early developmental history and current level of function^[3].

During the interview, the caregiver is asked to describe the individual’s behavior in three domains: social interaction, communication, and range of restrictive, repetitive, and stereotyped behaviors and interests. The examiner rates these behaviors to inform the results of the evaluation^[3].

The Autism Diagnostic Observation Schedule (ADOS)

The Autism Diagnostic Observation Schedule (ADOS-2) is another form of specialized testing for autism that can help diagnose autism spectrum disorder in children and adults. It consists of a semi-structured play session or an interview involving standardized activities and questions designed to lead to behaviors that can indicate ASD symptoms^[4].

There are five modules for examiners to choose from, depending on the individual’s age, developmental level, and communication abilities. For example, a young child will generally engage in a play session while an adult will be interviewed^[4].

The ADOS-2 takes around 40 to 60 minutes and relies primarily on the examiner’s observations of the individual’s behavior and social skills. The examiner converts their observations into scores indicating whether the symptom presentation is consistent with ASD^[4].

The Childhood Autism Rating Scale (CARS)

The CARS-2, or Childhood Autism Rating Scale, is a clinical rating scale with 15 questions. It’s intended for trained clinicians to use after direct observation of the person being evaluated for autism.

The CARS-2 can be used for people of all ages and has two different scales: a “Standard Form” for younger and lower-functioning individuals and a “High-Functioning” scale for higher-functioning individuals. The clinician can combine their observations with an unscored form called the CARS2-QPC or Questionnaire of Parent Concerns, where parents can record observations of their children^[5].

The Standard Form of CARS-2 is scored via the clinician’s ratings based on the information they’ve learned from their observations and the CARS2-QPC. The High-Functioning scale is also scored with the clinician’s ratings, but they must be based on at least two sources of information. These typically include direct observation and information from an individual who can describe the person’s behavior in various settings^[5].

While the ADI-R and ADOS-2 are primarily used for diagnosis, the CARS is frequently employed to evaluate changes in ASD symptoms over time. It can offer metrics to track a person’s progress, symptom severity, and intervention efficacy. The CARS also indicates when adjustments to current interventions may benefit the patient.

The Gilliam Autism Rating Scale (GARS)

The Gilliam Autism Rating Scale (GARS-3) is intended for individuals ages 5 to 22. It’s administered by a professional and can be completed by a parent, teacher, or caregiver. It takes approximately five to ten minutes and involves rating 58 items on six subscales based on the diagnostic criteria from the DSM-5^[6]:

• Social interaction
• Social communication
• Emotional responses
• Cognitive style
• Maladaptive speech
• Restrictive/repetitive behaviors

The GARS-3 uses the responses to each item to provide the individual’s probability of autism (unlikely, probable, or very likely), severity level, percentile rank, and standard score^[6].

What’s the Best Test for Autism?

There’s not one “best test” for autism spectrum disorder. Instead, it’s best to use a combination of autism diagnostic tools for an accurate diagnosis. For example, the ADI-R and ADOS-2 are frequently used in conjunction, and the CARS is often employed for ongoing symptom monitoring. A hearing and vision screening, as well as neuropsychological testing can rule out other health concerns that have similar symptoms to ASD^[7].

The diagnostic process frequently begins with developmental monitoring and screening, which are typical parts of well-child visits. When a child fails to meet developmental milestones, various diagnoses, including autism, are usually considered. Your child’s pediatrician may use a screening tool to determine whether an appointment with a specialist is warranted, at which point the various forms of autism testing discussed in this article can be administered. This is typically when children with ASD receive their diagnoses, although some individuals are not diagnosed until their adolescent or adult years^[8].

Detecting autism early often leads to improved outcomes. Early intervention services and tailored support can provide individualized treatment for children with ASD, helping them develop the skills they need to thrive and enjoy a high quality of life. As young children’s brains have high plasticity, interventions often make a significant difference^[9].

Adults with ASD who received early interventions have a higher probability of independence in adulthood. In addition, parents of children with ASD often experience lower stress levels and improved family function with early diagnosis^[9].

Challenges in Autism Testing

Autism spectrum disorder can be challenging to diagnose because there’s no official medical test that can confirm it. Instead, it’s necessary to look at a person’s behavior and developmental history. In addition, because ASD symptoms fall on a broad spectrum, autism spectrum disorder rarely looks the same in different people.

Conditions that commonly co-occur with ASD, such as structural language disorder, intellectual impairment, attention-deficit/hyperactivity disorder (ADHD), anxiety disorders, depression, and developmental coordination disorder, can also make ASD more difficult to accurately diagnose. ^[1]

Emerging techniques and tools may improve the diagnostic process for ASD. Genetic testing may offer insight into the genetic mechanisms of autism spectrum disorder, along with providing more targeted intervention and support strategies. Neuroimaging may also provide a better understanding of the disorder’s biological basis and identify new therapeutic targets that can inform the development of more effective interventions^[10].

Artificial intelligence (AI) and machine learning may enhance the analysis of children’s behaviors during early screening. Meanwhile, eye-tracking technology could assess children’s cognitive and social development by analyzing their eye movement patterns, as the eye movements of children with ASD tend to differ from those of children without ASD. While these emerging technologies are currently in the research and development stage, it’s believed they will eventually lead to positive changes in the screening and diagnostic process for autism spectrum disorder – as long as they are paired with the thoughtful, skilled eye of a trained clinician^[10].