Diagnosing PDA – Adults

You may be wondering whether a PDA profile of autism is a good fit for you or someone you know. This page is designed to guide you through the diagnostic pathway for adults in England and the various options available.


PDA (Pathological Demand Avoidance) profile of autism is usually identified during an autism assessment.

Because there is still academic/clinical debate about the terminology/classification of PDA, recognition of PDA is currently inconsistent. Identifying PDA can also be tricky because it may present in ways that may be different to the way many people, including clinicians, currently think of autism and there are overlaps in presenting characteristics between a PDA profile of autism and other conditions.

However, a PDA profile can, and should, be taken into consideration when undertaking autism assessments. This is in accordance with NICE Guidelines, which list demand avoidance as a ‘feature of possible autism’. Autism assessments should consider all the presenting strengths and challenges, including demand avoidance. The extent of, and reasons for, demand avoidance should be determined in collaboration with the individual. Demand avoidance can occur for different reasons, so it is important to understand that a PDA profile may not always be the best explanation.

PDA Society practice guidance for identifying and assessing a PDA profile collates the professional practice and experience of a multidisciplinary group of NHS and independent professionals and aims to aid assessment of a PDA profile and to distinguish PDA from other presentations of marked demand avoidance. Here’s a letter/email template which can be used to inform clinicians and autism teams about the practice guidance.

When assessing and diagnosing, clinicians can add appropriate descriptive terms to an autism diagnosis. Supplementary terminology such as a ‘PDA profile’ or ‘characterised by extreme demand avoidance’ are widely used. This type of signposting highlights the need for the use of helpful approaches by individuals, professionals and families.

Clinicians can use their own clinical judgement to describe an individual’s presentation of autism and remain within the guidelines of the diagnostic manuals. The National Autistic Society has produced useful information that describes autism profiles and diagnostic criteria in more detail.

This information is designed to guide you through the diagnostic pathway for adults in England. Please see separate information on the Diagnostic Pathway for Children.

Collating evidence

Securing an assessment for autism can be a daunting process, so it may be helpful to ask a friend or family member to assist.

Before starting the diagnostic process, it’s helpful to collate and organise your evidence. This can help you feel more confident when requesting a referral for assessment via your GP and provides medical professionals with clear reasons and explanations for your request. Your evidence should be clear, informative and to-the-point – these tips may help:

  1. Firstly, list some reasons why you think you may be autistic. Some examples could be: difficulties you’ve had in adulthood and childhood with social communication and social interaction, sensory differences, challenges with relationships or employment and your need for certainty/control. You may also like to comment on the degree to which you feel these points impact different areas of your life. The National Autistic Society provides some useful information about autism diagnosis for adults. ​NICE provides guidance and recommendations to professionals and individuals regarding Identifying, assessing and diagnosing autism in adults.
  2. Print off information about a PDA profile of autism and provide a brief summary of how you feel you fit the key features.
  3. Provide evidence from someone else who can support your descriptions of the challenges you’re experiencing. This person could be an extended family member, friend or a professional that has been supporting you, either past or present.
  4. Provide any information or reports from previous assessments or any conditions you’ve either been diagnosed with or treated for.
  5. Make duplicates of your information so that you have a file to keep for your own records and one that you can share with professionals.

​Why might an assessment/diagnosis be beneficial for you?

It’s quite common for people to go through life without any form of diagnosis or it may be that an existing diagnosis doesn’t seem to quite explain things – equally some people don’t feel a formal diagnosis is necessary but may benefit from the increased self-awareness that understanding PDA may bring, it’s a personal choice for each individual.​

The National Autistic Society provides some helpful pointers that could help you to convey why an assessment/diagnosis might be beneficial for you and how to explain this to others. For instance:

  • it may help you (and your family, partner, employer, colleagues and friends) to understand why you may experience certain challenges and what approaches may be helpful
  • it may correct a previous misdiagnosis and mean that any mental health challenges can be better addressed (however, it can be difficult to make a diagnosis of autism where there are severe mental health issues, or where someone is receiving treatment)
  • it may help you to get access to appropriate services and benefits.

Requesting an assessment

​The next step will typically be to make an appointment to see your GP – again, you may find it helpful to take a friend or family member with you. In some areas it is possible to refer yourself for an autism assessment, this is called ‘self-referral’. If a self-referral service has been commissioned in your local area, then you should find more information about this on your Local Authority’s website.

If you make an appointment to see your GP:

  • ​Share your thoughts and evidence with your GP – you may need to leave your information with them to read through and it may be forwarded on if a referral is made.
  • If your GP refuses to refer you for a full assessment, you can ask for the reason why either there and then, or at a future appointment, or in writing. You could ask to see another GP at the surgery for a second opinion. If you are unable to resolve this decision with your GP, you can make a complaint.

If you self-refer for an autism assessment:

  • You will typically be asked to complete a referral form with the option to either do this online or to print off and post the form to the assessment service.
  • You should then expect to be asked to complete a screening form to return to the assessment service, once received the assessment service will then decide whether or not you meet the criteria for a full assessment.

​Diagnostic pathways

There are three diagnostic pathways: your local NHS pathway, a referral to an NHS specialist or independent diagnostic centre, and private assessments. Each is explained in more detail below.

1. Local NHS pathway

The pathway varies regionally but may include a referral to an adult autism diagnostic team. In some areas there may not be an adult autism team so you may be referred to your local adult mental health services or individual professionals (psychiatrists or psychologists) – in this case you may need to check that the relevant team or individual is experienced in identifying and diagnosing autism.

2. Referral to NHS specialist or independent diagnostic centre

Some NHS autism diagnostic teams may agree that they don’t have the necessary experience/expertise to assess. You can request onward referral to an NHS specialist in the field – this is assessed on need and accessed via your GP. You can also request a referral to an independent diagnostic centre – this may involve your GP submitting an Individual Funding Request to the Integrated Care Board (ICB).

You can find more information about Individual Funding Requests (IFR) at NHS Commissioning Key Documents and the IFR process map 2023 from NHS England.

It is important to discuss these options with your GP to ensure that you follow the correct local pathway to secure any funding that may be required. It can sometimes be helpful if your local MP is able to support this request. If the request is refused you can usually appeal this decision or make a complaint, but you would need to seek further information about the process for appeal from your local health authority, as this varies according to local policies.

3. Private assessment

Private diagnosis (finances depending) is another option, although it’s still advisable to request a referral letter from your GP. Local services sometimes say that private diagnoses aren’t accepted. Provided the assessment has been conducted in accordance with NICE guidelines (detailed here), and by a specialist integrated autism team with age-appropriate expertise as defined in the NICE Quality Standards for Autism (also outlined below, in the next section), there should be very few grounds for local services not to accept the outcomes of a private assessment.

That said, even with a NICE compliant assessment, you may still find that your LA refuses to accept a report from an independent centre. Private assessments can be expensive and before booking an assessment we would recommend finding out if reports by independent centres are accepted by the LA so you can make an informed decision as to whether or not you wish to proceed. If an assessment has been undertaken and you encounter this problem, it can be helpful to ask the diagnosing clinician to contact the services on your behalf.

Please contact our Enquiry Line team for details of independent diagnostic centres which assess for Autism, and within that, give consideration to a PDA profile in accordance with NICE guidance. These services can be commissioned privately or by your Integrated Care Board if they have approved funding for an assessment (see point 2 above). Costs can vary between £2,000 and £4,000 – you will need to contact these centres directly for further information regarding costs, waiting times and their referral process. Please note that whilst the PDA Society researches all the services we signpost, the list should be taken as a helpful guide not as an endorsement and we can take no responsibility for the quality or the outcomes of assessments.

​The assessment

Once you have been referred to the adult autism diagnostic team, this service will decide whether they feel it is appropriate for them to carry out an autism assessment and/or an alternative assessment. The diagnostic assessment should begin within 3 months from the referral but may take considerably longer depending on the waiting times in your local area.

Autism assessments should follow a similar process whether it is being conducted by the NHS or an independent diagnostic centre.

The assessment should be conducted by a multidisciplinary team with age-appropriate expertise. NICE Quality Standards for Autism states the following:

A local adult autism team should include:

  • clinical psychologists
  • primary care services
  • nurses
  • occupational therapists
  • psychiatrists
  • social workers
  • speech and language therapists
  • support staff (for example, to support access to housing, educational and employment services, financial advice, and personal and community safety skills).

[Adapted from NICE’s guideline on autism spectrum disorder in adults: diagnosis and management, recommendation 1.1.13]

NICE guidelines on autism spectrum disorder in adults: diagnosis and management, recommendation 1.2.5 also states:

A comprehensive assessment should:

  • be undertaken by professionals who are trained and competent
  • be team-based and draw on a range of professions and skills
  • where possible involve a family member, partner, carer or other informant or use documentary evidence (such as school reports) of current and past behaviour and early development.

Dr Judy Eaton is an adviser to the PDA Society and explained that an adult assessment might involve talking with the individual, or the individual plus their parent, carer or partner if appropriate, to go through the person’s developmental history. Cognitive, communication and sensory assessments would be carried out and current functioning (e.g. employment, mental health etc) would be assessed.

NICE and the National Autistic Society provide further information about what an adult autism diagnostic assessment should involve.

Assessment outcomes

The diagnostician will tell you whether or not they think you are autistic. They might do this on the day of the assessment, by phone on a later date or in a written report that they send to you in the post/via email.

The report should give a clear diagnosis and a clear description of your profile of strengths and needs. If the assessment team has concluded that you do present with a PDA profile, the diagnosis may not state this explicitlyDifferent terminology is used from area to area and from clinician to clinician, some may refer to ‘Autism with a PDA profile/Autism with PDA traits’, others may give an autism diagnosis and refer to demand avoidance in the accompanying report. The most important point is that demand avoidance is highlighted as being a key feature for you as a signpost to helpful approaches.

Sometimes people are told they aren’t autistic or may be given a diagnosis they don’t agree with. You can discuss this with the professional or team who conducted the assessment and ask to be referred elsewhere, or you could consider paying for a private assessment. In being told the outcome of your assessment you may experience a range of emotions, some expected, some unexpected, and some that change over time. Where a centre is following best practice, you should be offered or sign-posted to follow-on services to support you as you process the outcome of your assessment. If a PDA profile is identified, you can contact the PDA Society’s Enquiry Line for free and confidential support.

Uncertainty or disagreement about the diagnosis

Consider obtaining a second opinion (including referral to a specialised autism team if necessary), if there is uncertainty about the diagnosis or if any of the following apply after diagnostic assessment:

  • Disagreement about the diagnosis within the autism team.
  • Disagreement with the person, their family, partner, carer(s) or advocate about the diagnosis.
  • A lack of local expertise in the skills and competencies needed to reach diagnosis in autistic adults
  • The person has a complex coexisting condition, such as a severe learning disability, a severe behavioural, visual, hearing or motor problem, or a severe mental disorder

Recommendations | Autism spectrum disorder in adults: diagnosis and management | Guidance | NICE, point 1.2.16

However, please note that funding issues can often delay or prevent the process of getting a second opinion and there may be no tertiary service in your local area.

What you can do if you are not satisfied at any stage of the process

  • Firstly, try to resolve any issues directly with the service involved, providing your feedback or concerns in writing – this helpful toolkit from Cerebra gives some good tips.
  • If this doesn’t resolve the issue, you can make a complaint.
  • Sometimes it can be helpful to explain the situation to your MP who may be able to support you.
  • Some people commission the services of a specialist solicitor, but this can be very expensive unless you qualify for legal aid.
  • If you have a complaint about a private diagnostician they should have their own complaints procedure, as required by the Care Standards Act 2000.