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Good and Bad Autism Assessments: What to Look For

Updated: 3 days ago

Professor Andrew McDonnell shares some things to look for when choosing a diagnostician to carry out an autism diagnosis.

As a practitioner with over 30 years of diagnostic experience, it is notable that there has been a recent increase in the number of provider organisations that conduct autism diagnostic assessments. For families and individuals, it is difficult to be confronted by long-term waiting lists for diagnosis. In this article, I am going to share some personal views about what to look for when choosing a diagnostician.

A man and a woman sit facing each other. One is a therapist, the other a client.
When it comes to choosing a diagnostician, there are some key things to consider.

Private vs Public Diagnosis

When I first qualified in the 1980s as a Clinical Psychologist, private diagnoses were a relative rarity. It was most common to receive a diagnosis of autism from either a Consultant Psychiatrist or a Clinical Psychologist with appropriate training. Relatively early in my career, I was fortunate to be influenced by Professor Lorna Wing, Dr Judith Gould, and many others who led the charge to understanding autism. Since this time, our knowledge base has dramatically expanded to the extent that even our understanding of the autism spectrum incorporates a complex range of conditions and experiences. I think it is important to reassure people that a high-quality diagnosis can be achieved, both publicly and privately.

Quality of the Practitioner

Psychiatrists and Clinical Psychologists are accountable to their professional bodies. It is always difficult to judge an individual practitioner as, despite their professional qualifications, it is often difficult to get a sense from a website what their approach to diagnosis entails. I would encourage anyone who is considering a diagnosis to clarify the approximate number of diagnoses the individual has conducted themselves. Like any market, can these practitioners provide testimonials or examples of individuals that they have diagnosed and the impact it has had on their life? On a personal note, when I advise families and individuals, I always encourage them to ask relevant key questions:

1) Does the person have experience of diagnosing both children and adults?

2) What experience do they have of diagnosing women on the autism spectrum?

3) Do they work as part of a team or as an individual?

4) What diagnostic tools (i.e., Autism Diagnostic Observation Schedule (ADOS), etc.) do they use?

5) Under what ethical circumstances would they not diagnose an individual?

Recently, there has been an increase in online diagnoses. Whilst there may be merits to such diagnoses in terms of their rapidity, I personally have serious ethical concerns where diagnosis is this impersonal. When determining the quality of a diagnostician, I would strongly advise people to ask for an informal consultation so they can determine whether this individual shows some kind of connection to the individual.

Developmental History

The increasing use of screening tools with statistical cut off points is important. However, diagnostic tools like the ADOS should be viewed as a guide, and only one component of any diagnosis. A clear developmental history (my own preference is to use the autism diagnostic interview (ADI-R) to take a thorough history) is very important. Significant numbers of individuals show early developmental delays in social communication, and in some instances developmental milestones, such as walking and talking. Interestingly, I have also worked with individuals who have shown advances at an early developmental stage which are not picked up by screening tools. For example, a person that I diagnosed at 18 years old was reported as having no developmental issues as a child. In reality, at 2 years of age, the individual was showing developmental advances - using sentences way beyond what would be expected of someone his age. It is important to understand that developmental histories are critical. Good diagnosticians and diagnostic teams will take time to talk to family and individuals about their early childhood development. In fact, a thorough developmental history is essential.

Use of Screening Tools

Increasingly, the use of screening tools such as the AQ50 (Autism Quotient 50) and others are necessary, particularly in diagnostic clinics that deal with high volumes of people. Please remember that they are called screening ‘tools’ for a reason. Screening for other health conditions is not an exact science – they just provide a guide or an indicator. The best way to think about screening tools is that they are a starter to your meal, not the main course. Screening tools are excellent at finding individuals who show considerable features of conditions such as autism, in particular behavioural issues. They are less good at indicating individuals whose features are more subtle. It is important to understand that if you are just given a screening tool and a short interview with a practitioner, that cannot in essence be a good diagnosis.

Sensory Issues

Our understanding of sensory issues in autism has significantly developed over the last 20 years. Many people on the autistic spectrum (and other conditions as well) experience quite profound sensory processing issues. I should also stress that I work with individuals on the autism spectrum who have relatively few sensory processing issues. In terms of this article, a good diagnosis should have either reference to a sensory assessment, or the diagnostic team/diagnostician should also include a sensory-based assessment.


We know that language greatly influences our thought processes. For individuals seeking a diagnosis, there are a myriad of terms on the internet and in social conversation that refer to autism or the autistic spectrum. It is more common these days to refer to individuals as ‘neurodivergent.’ The language that your diagnostician uses could be a good indicator of their approach to understanding autism. From my own perspective, my colleagues and I at Studio 3 have moved away from referring to phrases such as ‘autism spectrum disorder or deficits (ASD)’ as it presents negative connotations around the condition. The use of language both in written reports and in conversation with your diagnostician will give you clues about their stance.


I have personally experienced seeing diagnoses written in one-page letters to individuals with little explanation of the rationale and reasonings underlying the diagnosis. In my own personal view, this is bad practice. A person should be given a report with a clear opinion statement of why the individual has either received a diagnosis of autism, or been told that they do not meet the criteria. Most importantly, if a person’s diagnosis is confirmed, then the recommendations in any report should give the individual guidance on useful resources and some steps to help the individual process their diagnosis. With any written report, I feel it is very important that there is at least a 3-month follow-up session with that individual and/or their family to understand what they have processed from their diagnosis.

Time Taken

Good thorough assessments take time. I have examined the assessments conducted by my colleagues at Studio 3 over the last 3 years, and the minimum would appear to be a full working day spending time with the individual and talking to their supporters. In addition, this face-to-face time can increase from anything between 1-5 additional days depending on the complexity of the situation. To produce a meaningful report without using ‘cut and paste,’ which sadly seems to be prolific in the diagnostic industry, it takes Studio 3 staff 1 and sometimes 2 full days to produce a report.

Seeking Second Opinions

It is essential to understand that many individuals do not neatly fit in the diagnostic categories specified in the DSM-V. Whilst the vast majority of diagnoses are likely to be reasonably reliable, there are many situations where an individual may be told they are not on the spectrum, or even more unhelpfully that they are ‘borderline.’ If a person is uncomfortable with not receiving a diagnosis, in our modern society they can always seek a second opinion.

In conclusion, I have attempted to provide a personal perspective on diagnosis individuals with autism. Whilst this is not an exhaustive list, my parting advice is to spend time and don’t rush into choosing a diagnostician too quickly. Scrutinise their websites, talk to them if you can, get an understanding of their philosophy to diagnosis and practice, and remember that whether diagnosis is in the private or public sector, you are a customer and not a patient.

Written by

Professor Andrew McDonnell

Studio 3 CEO and Clinical Psychologist

Find out more about autism assessments from Studio 3 practitioners.


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