If you are wondering whether you or your child might have ADHD, one of the most useful things to understand is what clinicians look for. The ADHD diagnosis criteria in the UK are specific and well-established, and knowing them helps you understand both the assessment process and what a valid diagnosis requires.

ADHD (Attention Deficit Hyperactivity Disorder) is a neurodevelopmental condition affecting how the brain manages attention, impulse control, and activity levels. Diagnosis is based on clinical assessment, not a single test, and there are clear standards for what that assessment must include.

Who Sets the Criteria for ADHD Diagnosis in the UK?

Two frameworks are used. The DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition), published by the American Psychiatric Association, provides the most widely used diagnostic criteria globally, including in the UK. The ICD-11 (International Classification of Diseases, Eleventh Revision), published by the World Health Organization, is the equivalent international classification framework, also accepted by NICE for ADHD diagnosis in the UK alongside DSM-5.

In the UK, how those frameworks are applied in clinical practice is governed by NICE (the National Institute for Health and Care Excellence), through guideline NG87. Updated in 2025, NG87 sets out who can diagnose ADHD, what an assessment must include, and what criteria must be met before a diagnosis is made.

What Are the Core Diagnostic Criteria?

According to NICE NG87, for an ADHD diagnosis to be made, symptoms must meet three conditions:

  • 1
    They must meet the diagnostic criteria set out in DSM-5 or ICD-11
  • 2
    They must cause at least moderate impairment to psychological, social, educational, or occupational functioning, evidenced by interview or direct observation
  • 3
    They must be present in two or more settings, such as at home and at school, or at home and at work

Critically, NICE states that a diagnosis cannot be made solely on the basis of rating scales or observational data. A full clinical assessment, conducted by a qualified specialist, is required.

How Many Symptoms Are Needed?

The DSM-5 uses specific symptom thresholds that differ by age. Symptoms fall into two categories: inattention and hyperactivity/impulsivity.

Children (up to age 16) Adults and young people (17+)
Inattention symptoms required 6 or more 5 or more
Hyperactivity/impulsivity symptoms required 6 or more 5 or more
Presentations Inattentive only, hyperactive/impulsive only, or combined Same

A diagnosis can be made for predominantly inattentive symptoms, predominantly hyperactive/impulsive symptoms, or a combined presentation where both groups are significantly present.

When Must Symptoms Have Started?

Symptoms must have been present before the age of 12, even if they were not identified or assessed at the time. For adults seeking a late diagnosis, this means the assessment will look back at childhood history, sometimes drawing on school reports, family recollections, or other retrospective evidence.

This does not mean symptoms must have been disabling in childhood. It means there must be evidence they were present, even if the person managed to cope or mask their difficulties at the time.

What Else Does the Assessment Look At?

Meeting the symptom criteria is necessary but not sufficient on its own. According to NICE NG87, a thorough assessment must also include:

  • A review of coexisting conditions, since anxiety, depression, autism, dyslexia, and other conditions can produce overlapping symptoms and must be considered
  • An assessment of the person’s needs and circumstances, including family and social context for children, and occupational context for adults
  • Input from multiple sources, which for children typically includes parents and teachers, and for adults may include someone who knew them in childhood
  • Direct clinical observation or interview, not just questionnaires

This breadth is what separates a meaningful assessment from a superficial one.

Who Can Make a Diagnosis?

NICE is clear on this. According to both NICE NG87 and the NHS, a diagnosis of ADHD should only be made by a specialist psychiatrist (a doctor trained in mental health conditions), a paediatrician (a doctor specialising in children’s health and development), or another appropriately qualified healthcare professional with specific training and expertise in ADHD. A GP cannot make the diagnosis, but is the usual starting point for an NHS referral.

Cognitive Behavioural Therapy (CBT) adapted for ADHD addresses the thinking patterns, habits, and emotional responses that medication alone does not change. ADHD coaching is another option, focusing on practical strategies for organisation, time management, and self-regulation.

What Happens After the Assessment?

If the criteria are met, the clinician issues a written report confirming the diagnosis and setting out the basis on which it was made. This report is the document used to access treatment, request workplace adjustments, apply for school support, and evidence benefits claims.

If you are looking for an assessment, KPI:Access is a healthcare connector service that links adults and families with qualified specialists who carry out ADHD assessments for adults and ADHD assessments for children in London and Croydon. No GP referral is needed, and appointments can often be arranged within days. Specialists follow the same standards set by NICE and the Royal College of Psychiatrists.

KPI:Access is part of KPI:Health, a wider healthcare group that has connected over 300,000 people with assessments and treatments across the UK, with 99.2% rating their experience as good or very good.

Frequently Asked Questions

Typically no. NICE NG87 states that a diagnosis must be made by a specialist psychiatrist, paediatrician, or other appropriately qualified healthcare professional with specific ADHD training. However, some GPs may have undergone specific specialist ADHD training, which is uncommon but exists in certain NHS areas. In most cases, a GP will initiate the referral process rather than make the diagnosis themselves.

Symptoms must be present in two or more settings to meet the diagnostic criteria. If difficulties are only evident in one setting, a clinician would typically explore whether another factor, such as a specific environment or relationship, might be the cause rather than ADHD.

Yes. Any credible private assessment follows DSM-5 or ICD-11 criteria in line with NICE NG87. A diagnosis from a GMC-registered specialist using validated tools and a full clinical assessment carries the same clinical weight as an NHS diagnosis.

No. You can get in touch with KPI:Access directly without going through your GP first.

If you are ready to take the next step, our team is here to help. Book an appointment or learn more about ADHD assessments for adults and ADHD assessments for children through KPI:Access.

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