What is an ADOS?
Those looking into what assessment of Autism Spectrum Disorder (ASD) involves and anyone working or researching in this field are likely to come across people referring to ‘the ADOS’. This is an acronym that is short for ‘Autism Diagnostic Observation Schedule’, which is basically an assessment tool that is used by clinicians and researchers to help identify whether someone meets criteria for a diagnosis of ASD, or is presenting with features of ASD. It has been referred to as one of the ‘gold standard’ ASD assessment tools and was originally created by autism experts Catherine Lord, Michael Rutter, Pamela Di Lavore and Susan Risi in 1989. A revised second edition (ADOS-2) with an additional Toddler Module was released in 2012.
The ADOS is available for appropriately qualified practitioners (e.g. clinical or educational psychologist, speech and language therapist, occupational therapist, specialist nurse, psychiatrist, paediatrician, etc) to purchase through Pearson Clinical or Hogrefe in the UK (WPS in the US; MHS in Canada) costing around £2000 for the complete kit and around £6 per administration booklet.
The ADOS is NOT a ‘test’ for ASD, as some people mistakenly believe. An assessment that seeks to conclude whether someone meets criteria for a diagnosis of ASD should not rely on an ADOS alone. This is because the ADOS is an observational tool that focuses on observations of a person’s presentation, behaviour and social responses during a set time period (usually how long it takes to complete the activities – around 40-60 minutes). This means that it is merely a ‘snapshot’ of the individual’s behaviour and presentation and what you see during the ADOS assessment may or may not be representative of what the individual is like in most circumstances in their daily life. For this reason, it is essential to put observations from an ADOS assessment into the context of the person’s everyday life, likes, dislikes, particular areas of difficulty and the experiences they have had to date. It is also important to establish (perhaps with a discussion with someone who knows the person well afterwards), whether what is seen in an ADOS assessment session is typical of how that person would generally react and respond. It is not always possible to gauge this though.
The ADOS should be one part of a comprehensive assessment if the question being asked is whether the person meets criteria for a diagnosis of ASD. Other important information that should form part of a holistic assessment would include information from those that know the individual well regarding their functioning in different contexts (e.g. home, school/college/work, socially etc). This helps build up a picture of all aspects of their life and the particular areas of strength and need for an individual.
When assessing for ASD, there is a focus on the person’s social interaction, language and communication, cognitive flexibility (including routines, repetitive behaviours, obsessions, imagination, play) and also sensory issues. This is because these are areas where we see a pattern of atypical (different) functioning in ASD, compared to individuals who do not have ASD. Furthermore, ASD is a developmental disorder, meaning that it affects a person’s development in a number of areas from an early age and we typically see signs that an individual’s development is following a different trajectory (path or pattern) from infancy, although this is not always identified at this stage as differences from typical development can be very subtle.
In order to meet diagnostic criteria for a diagnosis of ASD, the individual must have displayed signs of atypical development in the areas of social interaction, language and communication, play, rigidity or sensory issues prior to the age of 3. For this reason, a comprehensive ASD assessment will involve gaining a detailed developmental history from a parent, other caregiver or someone else who is very familiar with the person’s development from birth (e.g. a grandparent). It is common that differences in a child’s development may not have been initially identified as a concern at the time, as they may not have been felt to be atypical (e.g. if this is a first child), may have been attributed to the child’s personality, or may have been explained away as something else. It is also often the case that when going through a developmental history with a family, they become aware of other differences in the individual’s development that they may not have perhaps noticed at the time but recognise in hindsight when asked about specific areas in detail as part of an ASD assessment.
So, back to the ADOS. The ADOS is an observational assessment tool; it involves direct observation of the individual being assessed, as opposed to information given by other people. This usually means the person being assessed either attending a clinic for a pre-arranged appointment, or someone trained in using the ADOS coming out to visit the individual being assessed at home, school or another appropriate place.
The ADOS tends to involve two practitioners undertaking the assessment, although it can be done with just one. Some practitioners prefer having a colleague present as a ‘second pair of eyes’ to observe anything they may have missed whilst they are administering the assessment and it can also be helpful for someone else to take notes to aid rating/scoring the observations afterwards. However, others prefer to administer and take notes themselves and in any case there may not be another practitioner available to do this.
For this reason, some practitioners will video the ADOS assessment so that they can play back the video and look for any observations that they may have missed. This is also common practice in research, where a second (or even third) person will also look at the ADOS assessment footage in order to make sure the observations are valid and reliable. In order to administer the ADOS, you need to have completed approved ADOS training. This is typically an intensive 5 day course delivered by an accredited trainer and usually those who receive training already have significant experience and knowledge in ASD.
In the latest version of the ADOS, the second edition (ADOS-2) published in 2012, there are five different ADOS ‘modules’, each containing a set of semi-structured tasks, activities and discussion topics, that map onto different developmental stages. These tasks and activities are designed to elicit the types of behaviours, interactions and responses that we assess when considering an ASD diagnosis, taking into account what we would expect at different stages of development.
The Toddler module is based on tasks suitable for children aged 12-30 months of age who may not yet be consistently using phrase speech. Module 1 is for children aged 31 months and older who may not be consistently using phrase speech. Module 2 is for children of any age who may be using phrase speech but who are not verbally fluent. Module 3 is for children who are verbally fluent and young adolescents. Module 4 is for verbally fluent older adolescents and adults. It is important to use the module relevant to the individual’s developmental stage in terms of their expressive language ability and understanding, which may not necessarily be the module indicated by their chronological age (e.g. for those with a learning/intellectual disability or a language disorder).
Module 1 and the Toddler module are both primarily play-based and include the examiner seeing if the child responds to their name and other attempts to gain their attention and elicit interactions. Module 2 is a mixture of the play based activities in Module 1 and the more conversational discussion in Module 3. Module 3 is based on both play and structured activities and also conversational discussion, similar to Module 4 but with a more child-focused stance. The tasks include construction of a puzzle, demonstrating an everyday task using actions and gestures, describing pictures, narrating a picture story book, creating a scenario using toy figures, creating a story using random objects, reciting a story from picture cards and discussing social relationships, school, careers, future plans and emotions. There is also the opportunity for free play during a scheduled break, as well as general chat to get to know the individual and a chance for them to ask any questions and say how they found the assessment. Module 4 is similar to Module 3, but is less play-focused and based more on chat and discussion.
Immediately following the assessment, the observations of the individual and how they responded and approached the different tasks needs to be ‘scored’ or rated using the ADOS scoring schedule. This is a framework where specific aspects of the individual’s social interaction, language and communication, repetitive and stereotyped behaviours, and sensory issues are given a numerical rating according to whether the person displayed typical responses and behaviours, or whether they presented as atypical or having difficulty in the specific behaviours rated that fall under these domains, and where appropriate, the degree of difference/difficulty.
Once all of the behaviours, responses and observations in the ADOS scoring framework have been rated or ‘scored’, an algorithm is used to convert the individual’s score to a ‘comparison score’. This is based on lots of data gathered by the people who developed the test and allows the assessor to work out whether the behaviours and responses they saw during the ADOS assessment correspond with a ‘high’ level of ASD features and thus a high probability of meeting criteria for a diagnosis of ASD, or a ‘low’ level of ASD features and a low probability of meeting diagnostic criteria. Comparison scores range from 0-10, with 10 representing ‘highly likely’ and 0 representing ‘highly unlikely’. The pattern of the scores in the different domains assessed is also relevant.
It is important to remember that an ADOS comparison score in itself should not used in isolation to make a diagnosis and that an individual may present differently in their ADOS assessment to how they would present generally in their everyday life, due to it being an unusual situation with new people that typically takes place in an unfamiliar setting. This is why it is crucial for those assessing the individual to be experienced and skilled in working with people on the Autism spectrum and also to have gathered information from a range of sources as part of a holistic assessment to build a picture of the individual and how they function in all aspects of their life. It is useful to have also directly observed the individual in a different setting, preferably one where they are more comfortable (e.g. in school).
In addition to the quantitative (numerical) comparison score, the ADOS also generates very useful qualitative (descriptive, rather than numerical) information about the person’s functioning in the areas of their social interaction, language and communication, cognitive flexibility and sensory issues and this can be just as important, if not more important, data for those undertaking the assessment.
For further information on what constitutes a high quality ASD assessment for children and adolescents aged under 19 in the UK, the National Institute of Health and Care Excellence (NICE), have produced NICE Guideline CG128, which is based on a systematic review of available evidence and also covers recognition and referral.
Similar guidance from NICE for adult ASD assessment can be found in NICE Guideline CG142 that covers diagnosis and management of ASD.
In terms of questions I have been asked by families, individuals being assessed and other professionals, I will try and answer a few here…
Who will be present during the ADOS assessment?
Many parents ask this and it is a very valid question, as it can be useful to explain to the individual being assessed who will be there in the room in order to prepare them for what to expect during the assessment. The answer to this will depend on the practitioners undertaking the assessment and this can be a good question to phone up and ask prior to the ADOS assessment, or at the beginning of the session when the practitioner explains what will happen.
For younger children, it is important for a parent or other caregiver to be present so that the child feels reassured and at ease. The parent or caregiver may also be asked to assist with the assessment, usually simply involving speaking to or interacting with their child in a specific way requested by the practitioner.
For older children who are able to tolerate being separated from their parents or caregivers, they are generally asked if they would mind completing the ADOS assessment whilst their parent or caregiver remains nearby in the waiting room (or equivalent). This is simply because they may look to their parent or caregiver to answer for them, may behave differently with them present or may become embarrassed due to the nature of the questions asked (e.g. ‘does anyone in your family annoy or irritate you?’). However, if the child would prefer that a parent or caregiver remain in the room, this can be discussed.
Adults generally complete the ADOS unaccompanied, but there may be one or two practitioners present.
The ADOS is essentially an autism test though isn’t it?
No, it is a semi-structured set of tasks, activities and interactions that aims to elicit behaviours and skills that are associated with ASD, as the observational component of a wider assessment. The actual assessment session is play-based for younger children and for those who are older, is focused more on a chat to get to know the person and what they think about things and there are no ‘right or wrong answers’. Individuals who are assessed using the ADOS may worry about being ‘tested’ or evaluated if it is referred to as a test or exam, many of those assessed actually enjoy it!
Can you do the ADOS again / more than once?
ADOS assessments can be repeated, although if there has only been a short space of time since the individual last did it, they are likely to respond in a similar way. There needs to be a clear rationale for undertaking a further ADOS, such as if the individual’s presentation has changed significantly in one of the areas the ADOS assesses and the question has been asked regarding whether they still meet criteria for a diagnosis of ASD. For example, it may be unclear following a comprehensive ASD assessment that includes an ADOS whether a child meets criteria for a diagnosis of ASD and the assessment team may decide to review the child and re-assess them in a further 12 months in order to gather further information and monitor the child’s development. In this sort of situation, the ADOS can be readministered.
If the ADOS suggests ASD, that means a diagnosis can be given right?
Not necessarily, a decision about whether someone meets criteria for a diagnosis of ASD should never be taken based on the results of an ADOS in isolation. Individuals with other conditions or difficulties can present similarly to ASD (e.g. learning/intellectual disability, attachment issues, selective mutism, significant anxiety) and would thus be likely to achieve an ADOS score suggestive of ASD, therefore it is important to interpret the observations in the context of background information and a full developmental history. It is not uncommon for someone to have an ADOS score highly suggestive of ASD, but their developmental history and information from other sources regarding their functioning contradict this because there is another explanation underlying their presentation. This highlights the need for somebody skilled and experienced in assessing ASD who also knows about other similarly presenting difficulties to look at the ‘whole picture’ as part of a comprehensive assessment.
As always, if you have any comments, questions or want to discuss anything I’ve talked about – feel free to respond below!
