How is Autism Diagnosed?

At I AM we get many calls to our Help and Advice line from those seeking a diagnosis of autism. This blog post aims to outline the key information about this process.  

Autism Spectrum Condition (ASC) is a neurodevelopmental condition, this means that it is thought to be caused by the way that the brain develops and operates. ASC is a lifelong condition, meaning that an individual is born with ASC and it will be a part of their life for all of their life.

Research has shown that genetic factors are involved in ASC and it often runs in families, although this is not always the case. Our genetic makeup is a bit like a lucky dip on the lottery, you’re never quite sure what numbers you are going to get!  That said, there will be huge differences between one individual with ASC and another individual with ASC – even in the same family. Everyone is unique and shaped not just by ASC but by a whole myriad of other unrelated factors.

Individuals with ASC may have differences in their language and communication, challenges with social interaction and communication, rigid or repetitive behaviours or difficulty adapting to change, and sensory issues such as hypo or hypersensitivities. There is, however, a great deal of variety in how these indicators appear and in the severity of their impact within individuals which is why autism is seen as a “spectrum”. As said each individual will be different.

For a diagnosis of ASC to be made professionals look for patterns in the person’s developmental history, their day to day functioning and their observable behaviour that might be common within the expected profile of ASC.  These patterns are then compared with criteria that are defined in professional manuals such as in the Diagnostic and statistical manual of mental disorders (DSM-5) and the International classification of diseases (ICD-10).  These manuals specify criteria that need to be met in order for a diagnosis to be made.

Sometimes the characteristic behaviour patterns of ASC can be caused by other “conditions”.  It can also co-occur with other neurodevelopmental conditions such as ADHD or Dyspraxia and some medical and/or mental health conditions such as anxiety. In some cases, particularly with high functioning individuals the differences caused by ASC can be subtle and more difficult to identify.  There is also some evidence to suggest that ASC is less easily recognised in girls leading to under-diagnosis. It is thought that around 1% of the population has ASC.

The National Institute for Health and Care Excellence (NICE) published updated guidance on the recognition, referral and diagnosis of Autism in 2017 and these can be found here It is well worth reading this guidance and it also contains useful checklists of signs and indicators across a variety of ages, these checklists can be found here

Autism assessments for children are carried out by teams of professionals based in Community Paediatrics or Child and Adolescent Mental Health Services (CAMHS).  The referral route to access an assessment for autism depends on the age of the child. For younger children discuss your concerns with your Health Visitor who will be able to make a referral.  For school age children most assessment services across Greater Manchester would ask for referral information to be provided by the child’s school, as they will have lots of relevant information about your child and their functioning. Discuss any concerns with your child’s class teacher or the Special Educational Needs Coordinator (SENCO) at your child’s school and they can make a referral.  For adults, assessments are carried out by autism teams and they will require a referral by your GP.

If your GP is referring you to the autism team they should provide a letter that provides some background information and medical history. The autism team should provide you with a named point of contact who will coordinate the diagnostic process and communicate directly with you.

The assessment should consist of the following

    • detailed questions about parent’s or carer’s concerns and, if appropriate, the child’s or young person’s concerns
    • details of the child’s or young person’s experiences of home life, education and social care
    • a developmental history, focusing on developmental and behavioural features consistent with ICD-10 or DSM-5 criteria
    • assessment (through interaction with and observation of the child or young person) of social and communication skills and behaviours, focusing on features consistent with ICD-10 or DSM-5 criteria
    • a medical history, including prenatal, perinatal and family history, and past and current health conditions
    • a physical examination
    • consideration of the differential diagnosis to identify if it is autism or something else
    • systematic assessment for conditions that may coexist with autism
    • Other assessment tests may also be added to explore other conditions or issues

After the assessment, you should receive a report that will detail the findings and be given an opportunity to discuss this with a member of the autism team. They should also be able to signpost you to further sources of support.

It may be that there is not enough evidence to make a diagnosis of ASC but if this the case you should be directed to either further assessments, if some other condition is suspected, or signposted to other forms of support.

Sometimes it can be difficult to reach a definitive diagnosis, especially with younger children or those who are higher functioning, in these cases sometimes a watch and wait approach is taken with reviews being scheduled. Although this can feel frustrating, for a lifelong condition like ASC it is important to be certain about the diagnosis before it is made.

If you or your child are experiencing particular challenges at home, at school or with mental health it is important to discuss these challenges with the autism team who may be able to signpost you to other support. You should also discuss any concerns about your child’s needs in school with their teacher or SENCO.

A child does not require a diagnosis to receive support in school – support provided should be based on your child’s needs irrespective of a diagnosis. If you do not feel that school are providing sufficient support parents or carers can write directly to their local education authority and ask for an Education Health and Care Plan (EHCP) Needs Assessment. Whichever route you choose the voice of the parent or carer should be listened to and taken seriously.

There are often long waits for an assessment for autism, in some cases over a year. Some parents and adults choose to pay for a private assessment. This can be expensive. If this a route that you decide to choose then it is important that whoever carries out the assessment is properly qualified and that the assessment is sufficiently thorough to be recognised by other bodies such as the local education authority, NHS, etc. in the future. Check with the provider of the assessment beforehand and ideally get written confirmation of this in advance, to ensure that this is the case.

Below are some contact details for diagnostic services across Manchester for reference and information purposes only. We cannot, however, guarantee these are up to date, the services that are provided or waiting times.

Trafford Extended Services – Bolton, Trafford and Manchester – Trafford Extended Service (TES) | Greater Manchester Mental Health NHS FT (

Axia – Salford – Axia ASD – Cheshire Autism Spectrum Disorder and Aspergers Diagnosis – Autistic Diagnostic Service (

Lanc UK – Bury and North Manchester Learning Assessment and Neurocare Centre (

Stockport NHS – Stockport Stockport ASD – ADHD adult diagnostic service: Pennine Care NHS Foundation Trust

Tameside – Tameside & Glossop Integrated Care Tameside Autism Network Referrals

To find out about how I AM can offer support contact us at admin@i-am or give us a call on 0161 866 8483 
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