What is ADI-R and How Does it Work?

The Autism Diagnostic Interview-Revised (ADI-R) is one of the most widely used diagnostic algorithms in determining whether or not children have autism spectrum disorder (ASD). Together with the ADOS (Autism Diagnostic Observation Schedule), it is the diagnostic tool of choice for many public school systems and psychology professionals when evaluating kids suspected of being on the spectrum.

Unlike the ADOS, however, ADI-R does not directly involve the child—instead, it is an interview conducted by a trained researcher or psychologist with the child’s parents or other caregivers. The ADI-R focuses on the developmental history of the child, relying on the memory of the people closest to them – mom and dad.

As more and more studies have shown the benefits of performing early intervention in ASD cases, there has been more and more pressure to make an early diagnosis so that treatment can begin as soon as possible. In 2015, the first long-term study of treatment outcomes for ASD was published by the University of Washington and showed definitively that early intervention improved IQ, adaptive functioning, and communication among kids who received it.

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The ADI-R is shown to be most accurate when used to assess toddlers, age 4 and up. Although the ADI-R has struggled to provide accurate results for earlier diagnosis, if you have a child of any age who is showing symptoms of ASD, you are very likely to go through an ADI-R interview at some point.

Here’s what you need to know.

A Research Tool Turned Diagnostic Tool

The ADI was originally created in 1989 as a tool for researching the sudden explosion in autism diagnoses around the country. The interview was aimed at investigating the behavior of adults or children over the age of five, with a mental age of at least two.

But health professionals also saw the utility of ADI as a screening tool to standardize autism diagnoses and make detection easier. In 1994, the ADI was revised, shortened, and adjusted so that it could be used to make assessments of children as young as 2 years old, though it is most effective for kids that are at least 4.

Today, it is published by Western Psychological Services (WPS), the same company that produces the ADOS exam.

There are 93 questions on the ADI-R, although it can seem like a lot more when you are the target of the interview. Most clinicians can get through the list in about 90 minutes.

The questions are all designed to identify behavioral issues related to the three main areas involved in an ASD diagnosis:

  • Communication and language skills – The child’s history of speech development and current abilities to sustain conversation.
  • Social interaction issues – How the child interacts with other people and how they show or interpret emotional responses.
  • Repetitive and obsessive behaviors – Stereotypical ASD behaviors such as a fixation on unusual items, repetitive hand motions, or repeated use of short, out-of-context phrases.

Looking at the Entire Picture of a Child’s Developmental Progress

Although these general categories are fairly well-known, the ways they manifest in a child’s behavior and when they appear are also important.

As a concerned parent, any of the classic signs of autism are likely to jump out at you and cause the alarms to go off, but observing any one of these things by itself isn’t necessarily a cause for concern. Individual traits that may be typical in ASD cases might mean nothing in isolation, and may appear or disappear at a certain age without any other signs of autism ever showing up. In these cases there is absolutely nothing to worry about.

The ADI-R is designed to look past isolated traits that might give a false positive. To get at the long-term developmental disability that a true ASD case will show, the interviewer essentially takes a case history that covers:

  • Medical history and prior diagnoses
  • General behaviors, both past and current
  • Developmental milestone dates
  • The history of speech and language development
  • Destructive or aggressive behaviors

The questions are scored on a scale of zero to three, with three being the most abnormal result. Each question may also be coded according to the child’s age at the time it was first noticed, or if the behavior is something parents are still regularly seeing.

The ADI-R Has Limitations, and Is Only One Tool in the Toolbox

The ADI-R is not usually the only tool used to make an autism diagnosis. In fact, it may not be used at all. The technical criteria governing what is and is not autism is covered by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a standard reference text for psychiatric conditions. A trained psychiatrist or other expert clinician is free to use whatever tools they prefer when making their diagnosis, or ruling out ASD. In many cases, they may interpret results from the ADI-R or any other test as only one part of their complete evaluation.

However, the ADI-R interview is popular and frequently used in psychiatric circles. It’s also commonly used in American school systems, which are required to conduct evaluations on children suspected of having ASD under the rules of the IDEA (Individuals with Disabilities Education Act) of 1990. The Centers for Disease Control and Prevention also recommend testing of all children at 18 and 24 months.

Although the ADI-R has been found to be very effective in older children, there have been many studies showing that it is less reliable when used to diagnose children younger than four. New algorithms and questions are being proposed, but it’s also important to note that the ADI-R is rarely if ever the only diagnostic tool used. It may also be re-administered at different ages to test for validity.

Although it can be difficult to go through an ADI-R interview, it can also be useful for parents, even if it doesn’t result in an ASD diagnosis. The nature of the questions themselves can help you become more objective about evaluating your child’s behaviors, allowing you to recognize any developmental issues that might be present so you can get the early intervention your child may need.