Assessment and Diagnosis (Autism and ADHD)

Assessment Pathways

There are a few different routes for assessment in the UK:

  1. NHS – Referral via GP
  2. NHS Right to Choose (RTC) pathway in England – Referral via GP
    • NHS RTC allows patients to have NHS care by any part of NHS England
    • Several NHS areas have chosen to outsource their ADHD and autism assessment services
    • There are private companies providing NHS services to NHS standards
    • RTC allows referral to NHS outsourced providers
    • For additional information on Right to Choose, see Right to Choose, ADHD UK
  3. Private – This is the only option for combined autism and ADHD assessments

Considerations:

  • Adult combined autism and ADHD assessments are not available via NHS or RTC pathways, although people should be able to have separate assessment options via the other pathways
  • RTC information is subject to change
    There are changes happening to NHS Right to Choose. See Right to Choose, ADHD UK for updated information
  • Some providers cannot titrate (applies to the adjustment ADHD medication dosage), and others can’t provide ADHD medication long term without a ‘shared care’ agreement with your GP
  • GPs may reject shared care agreements with private providers

Barriers to Having Diagnoses

There are many barriers to accessing a diagnosis. Some are outlined below:

  • Structural / System Barriers
    • Waiting Times
    • Lack of NHS assessment pathways
      For example, in Scotland adult neurodevelopmental pathways are not available in many NHS boards
    • For historical reasons (see section below), many people were not able to access assessment or diagnosis
  • Recognition and understanding
    • Recognition of traits
      Some people may not recognise traits in themselves, or those around them may not recognise them either.
    • Masking – people adapting to cope, mean traits become less visible
    • Professional awareness – knowledge and understanding can vary between professionals. This affects whether someone is referred for assessment, and how their experiences are interpreted.
  • Process and criteria
    • A lack of available evidence can be a barrier for adults undergoing an ADHD assessment. Diagnosis typically requires evidence that traits were present before the age of 12, across different settings. For children, this evidence is often obtained from parents and schools.
  • Personal and Contextual Factors
    • Intersectionality – Traits often present differently across backgrounds, including gender, age, race, ethnicity and co-occurring conditions
    • The assessment process can be emotionally demanding, as can coming to terms with a diagnosis. Some people may not have the emotional bandwidth to pursue assessment, or may feel that the potential downsides outweigh the benefits.
    • Access and practical barriers of the assessment process
      Navigating referral processes, obtaining evidence, completing forms, and attending appointments can be challenging. These barriers can disproportionately affect those already experiencing difficulties.

These barriers are often interconnected. Difficulties in recognition, access and systems can combine to delay or prevent diagnosis.

Autism and ADHD Historical Timeline (UK context)

Understanding the history of autism and ADHD diagnosis helps explain why many people weren’t diagnosed earlier in life. Diagnostic criteria, awareness and services have changed significantly over time.

The timelines below highlight key milestones, particularly those relevant to diagnosis in the UK.

Autism:

  • 1943 – First clinical description (Leo Kanner)
  • 1980 – Formal diagnosis available as a formal diagnosis (DSM-III)
  • 1992 – 1994 – Asperger syndrome introduced as a diagnostic category
    1992 in ICD-10 and 1994 in DSM-IV
  • 2007 – Adult autism prevalence recognised in the UK
    Identified in the Adult Psychiatric Morbidity Survey
  • 2009 – Autism Act (England)
    First disability-specific legislation, improving recognition and services for adults
  • 2013 – 2019 – Unified ‘autism spectrum disorder’ (ASD) diagnosis
    Subtypes (including Asperger syndrome) removed
    DSM-5 (2013) and ICD-11 (2019)

ADHD:

  • 1968 – 1990 – Early diagnostic concept
    ‘Hyperkinetic reaction of childhood’ recorded in DSM-II
  • 1980 – Attention Deficit Disorder (ADD) recorded in DSM-III
    ADD with or without hyperactivity
  • 1987 – 1994 – ADHD terminology established
    ADD revised to ‘Attention-Deficit Hyperactivity Disorder (ADHD)’ (DSM-III-R)
  • 1994 – ADHD defined with 3 sub-types (DSM-IV)
    Inattentive, hyperactive-impulsive and combined
  • 2000 – NICE recognises childhood ADHD (NICE TA13)
    (Applies to England, Wales and Northern Ireland)
  • 2008 – NICE recognises ADHD in adults (UK)
  • 2009 – SIGN publishes ADHD guidance for children (Scottish Intercollegiate Guidelines Network, Scotland)
  • 2013 – ADHD subtypes replaced with ‘presentations’ (DSM-5)
    Presentations reflect how traits can present differently over time
    2018 – NICE guidelines highlight under-recognition in girls and women
  • 2019 – SIGN withdraws its ADHD guidelines (Scotland)

Combined autism and ADHD (Both):

  • Pre-2013 – Dual diagnosis typically not permitted
  • 2013 – Dual diagnosis permitted (DSM-5)
  • 2018 – ICD-11 published (WHO), recognising co-occurring autism and ADHD
  • 2022 – ICD-11 comes into effect internationally (gradual adoption)
    Adoption varies by country, including the UK

What this means in practice:

  • Diagnostic systems forced single labels
  • Co-occurrence was real, long before it was diagnosable
  • Many adults were not missed – they were never eligible for diagnosis before
  • Support needs existed before recognition did

References